• No results found

The absorption of amino acids from the mammalian intestine

N/A
N/A
Protected

Academic year: 2020

Share "The absorption of amino acids from the mammalian intestine"

Copied!
282
0
0

Loading.... (view fulltext now)

Full text

(1)

THE ABSORPTION OF AMINO ACIDS FROM THE MAMMALIAN INTESTINE

John Basil Wilson

A Thesis Submitted for the Degree of PhD at the

University of St Andrews

1949

Full metadata for this item is available in St Andrews Research Repository

at:

http://research-repository.st-andrews.ac.uk/

Please use this identifier to cite or link to this item:

http://hdl.handle.net/10023/11244

(2)

A l æ s i s

maizawTED fob z m zBcia®

OS’

jXxjscr ot i>iaL030P!iy

OF

OSE m m m s i s i c e a s .■cie^«?3

3Y

(3)
(4)
(5)
(6)
(7)
(8)

î

r

*

_ T _

•sm

iai.3HPTI3B j ? AUIBO ACH):

(9)

ProQuest Number: 10166126

All rights reserved

INFORMATION TO ALL USERS

T h e q u a lity of this reproduction is d e p e n d e n t upon th e q u a lity of th e copy su b m itted .

In th e unlikely e v e n t th a t th e a u th o r did not send a c o m p le te m anuscript

and th e re are missing pages, th e s e will be noted. Also, if m ateria l had to be rem o ved , a note will indicate th e d eletio n .

uest.

ProQuest 1 0 1 6 6 1 2 6

Published by ProQuest L L C (2 016). C o pyrig ht of th e D issertation is held by th e Author.

All rights reserved.

This w ork is p rotected ag ain st u nauth orized copying un d er T itle 17, United S tates Code. M icroform Edition © ProQuest LLC.

ProQuest LLC

7 8 9 East Eisenhow er Parkway P.Q. Box 1 3 4 6

(10)

- s

•The I n v e s ti a t loDs o f r*ooent year j d e a lin g w ith the su b je c t o f i n t e s t i n a l aboorptlon Imve* on th e w îiole, tended to confirm th e view ttm t tlio

membrane o f th e ;u t, lirovlded th a t i t s n o m a l co n d itio n la igerved^ la n o t to bo c la a se d a s a

oasolvo diap!ira in between blood on th e one a id e and s o lu tio n In the g;ut on tbx) other* r e v e r tlie le a s . I f th e Gonolusiwi tlm t tlie ep ith eliu m o f the v l l l l In some way a c ts a s an a c t iv e au ;ent In a b sorp tion be admitted 9 we are s u l l l very 1 'norent renardIn^ th e

ex ten t to which I t s a c tio ; la m odified by cihan ea In th e p h y sica l and chem ical environment o f the c e l l s w ith in th e lim it s o f Snterferenoo w ith bloplasm lo p ro cesses 9 l i m it s soon outstepped «lion concentrated

s o lu tio n s or s o l u t i œ s o f d e le te : Icua »u )stances a r e

# p

used by th e in vostln ator" *

( aymouth e ld (19)2)^

(11)

5

e n tr a i I n t i ^ u o t i o n »

I# General imbure o f problem#

II* stn '.o tu re and h: e t o lo r y o f tîx? [^ t* I I I * H lsto r lo fd review *

IV* Lîodem work*

V# A bsorption o f our ara*

VI* Absorption o f f a t s *

V II. i^ a o r p tlo n o f amlno a c ld s# V III* P ren ait p o s itio n *

:.9oUoD P.40

"^ates o f A bsorption o f to ln o a o iâ a froQ upper and low er lo o p s o f th e sm all I n t e s t in e o f a ts *

I# Intrcx&iotion#

II* l a s t work* I I I . fr e se n t work#

a ) method*

b ) r e s u lt s . o ) 1 la o u sslo n #

IV. Simoary.

o o tla n *4*. f # l 3 l

(12)

4

-Cats anâ o f -Cats vbdôov l ret!jane AnaoetW ala*

I# In tr o d u c tio n .

I I . r%st work.

I I I . Preaont w r k .

a ) Method.

b ) l o s u l t s .

. o ) D ism issio n .

IV.' umaa!?y#

. .

i%i9ral I Is o u s o lo o . P.1S6

V

en era l ummar^. p .176

(13)

• s «*

G ^ B ^ R A L I B T R G P U C 2 I 0 B

I# r>8nor&l nature o f pt*o.>laa»

II# SGruoturo and hlatoloi^ÿ^ o f übo t# t#

I I I # I s t o r lo a l ~*3vlw?#

IV , üodw o ®oHt#

V# AUaorptlcm o f su g a r s .

VI# Abao2*:JGÎon o f fa ta #

VII* Absorption o f aain o aoida#

(14)

w ô «

IK ''oi/ ■a s t i n

.

a ) r-'Operal im turo of

ÂDsorptlan i s th a term a p p lied t o tbe paoaa o o f aubstanooa in to the blood stroan# ohothor from tbo body aurfaoo» I'roa tbo body c e v l t i o a , th o lym ^i

□poooa, o r from any ornana o f tbo body. Tîü» ab sorp tion

o f foodotraffa tokoo p la o o , in vortobratoo* tbrouf^h tho a lia o n ta r y oanal# Food la d i^ostod in order that i t

rîioy be absorbed. The dlQoated food thas d in ln ia h e s

in q u a n tity as i t paasoa t b i w ^ th e allm ontary o a n a l, and th e fa o o es con tain tho u ndinested or I n d ig e s t ib le r e s id u e .

Th? aXimsntary canal shows oonelderabl e d iffe r e n o e a in atru otu re aJoiic i t s le?ir’tih| th o se d iffe r e n c e s de end on the fu n c tio n s o f tho v a rio u s p arts# In tho mouth end oosophejus a b so lu tio n I s a t a minlEiun inertly bocouao o f th e tliio lîn e ss o f tho e p ith o llu a and p a r tly booauso o f tho rap id passa o o f tbo food throu'^h th o se p o r t s . Abaorptlcm ta k es p la c e to a sm a ll ex ten t only Ir the stomach# I t i s e n e r a lly tau ht tlia t water i s n o t absorbcKi irom the sto o a o h

(15)

7

-AlooboX Is eb3ort)#d to aorao o z te n t# Also* do

n o t soAQ to bo ao30Xt>oci tm lesa prooent in tsuoh QpAAtor ooooentr At ion g tlian o o o j f in no!%ml d i e t s f ougmr . la

Absorbed o l t h d l f f l e n i t y . OolXoldAl im torlA la auoh A3 p rotein * fa t* and otarch* nhioh arm th o im ln food jt^ ata n o os apart fi*gq smtor and a lta * are b ^ lte n doan in th e I n to o tln a l ooim l by h y d r o ly tic onzyaes in to

so lu b le* d if f a a ib lo .robstonoea (C itarllnc# 1896) • Thus p rotoin a ero broken doon in to azalno acid a o r p o ly p e p tid es * in so lu b le f a t a are broken dom In to f b t t y aoida* uhioh re a o t -aith b i l e a c id s to Ibra vater^ a olu b lo * d i f f u s i b l e oozg^lo&ea* and otaroh I s broken doan in to sunara.

T his forcm tlon o f water - s o lu b le d i f f u s i b l e aubatanoea i s not* however* th e o n ly a l j n i f i o a n t r e s u l t o f tbo breakln ; do «an o f fc^ od stu ffa. I t l a e s s e n t i a l th a t the breakdoan products should bo non* a p e o ific s u b sta n c e s . The importance o f t h i s can b e aeen w ith p r o te in s . r o to ln a o f one s p e c ie s o f an In a l e r e t o x ic I f in je c te d In to the c ir c u la t io n o f another 3i>ooie:j* b u t the same p r o te in taken in to th e i n t e s t i n e i s s p l i t up in to n o n -a p e o ific and n o n -to x ic amino a c id s or p o ly p e p tid e s.

Tlaero are u cid ition al ad van ta e s in th e

(16)

• B ■»

end t b ia l a only p o sa lb lo I f tha food aubatanoea d w lv o d from p lan ta or anlimila ei*o f i r s t bTXJkan

doan t o r o la t l v o î y alciplo saol^^culos* ^ona sQbatacoaa suoh aa wôt'ir» and aolubXo s a i t a l l k o sod ln o c h lo r id e oro absorbed unohanced#

Tho sm all i n t e s t i n e , # i l o h posaossoa a very la p fo int(n*nal aurfaoo on asoount o f I t s f o ld s and v l l l l , l a th e T?seln orr;an fo r absor^A lon. AbsorptloD beglna In the duodenum^ m â tho prodtiota o f d ig e s tio n have la r g e ly disappeared by the time the I n t e s t in a l co n te n ts reach th e lleo co X io v a lv e a t t h e ooomonoeoont o f tho larr e In t i s t l n e ; e a te r la absorbed In the la r g e I n t e s t in e but I t s powers o f ab sorp tion o f oth er m a te r ia l 0 are very sm all# A bsorption ta k e s p la c e

o h le fly In th e upper part o f Wae sm all I n te s tin e # /vfter tho food m a te r ia ls p ass through th e I n t e s t i n a l

ep ith eliu m th ey reach e it h e r th e blood v e s s e l s (p o r ta l t r ib u t a r ie s ) o r t2ie lym phatlo v e s s e l s or la o t o a ls # In gen eral te r n s , th e p ro te in s ard oarbohydrateo pass in t o the blood v e s s e l s , and th e f a t s p a r tly in to tho blood v e s s e l s end p o r tly in to th e la c t e a ls *

Thus, In tho i n t e s t i n e , th e fo o d s tu ffs are

(17)

•* Q ’ •»

thô oï»ryBnl^ or o f ro a o tln - to fo r a th o o>i^rttotorl3tio

auhstanooa o f tho body. Tho Ibra In ^ l o h tbo

3u*03tanoo la prosont In th e I n to a tin o la o f d e o la lv o Iraportônoa f o r th o q u o a tlo - o f ab ab rp tlc • D iffu sio n i s on ly p o s s ib le In aqueouo o r lip o id s o lu t io n . C ertain o f th e a ij 0 3 t l v e p r o c e sse s produoe e a i l l j d lT fu s lb le

sob 3 tances* e .; > onlno a c id s In p ro te in 01 r e s t ion#

I t has been supposed th a t th er e o u st be prooeaaoe idiloh re r e la t e th e liat ire and ocio^int o f su b stan ces

absorbed* In r e la t io n t o th e r.eeda o f th n orf'snism#

Dut t h i s has n ever been proved . S ta r lln r emphasised

th e f a c t th at tho r*oraal I n t e s t in e absorbs overythln^ th a t I s ccaTverted in to a d i f f u s i b l e foiro In I t s lumen* lo d ep en d ertly o f th e needs o f the b od y.

I t I s very d i f f i c u l t to fin d a tr u ly p h ysiolof^ leal raethod f o r ab sorp tion experim ents* The I n t e s t in a l

cRiOosa I s extrem ely s e n s i t i v e t o a lt e r a t io n s o f

tem perature end blood flo w . For example* the

ab sorp tion o f olicjbvq from on s o la te d lob p o f tSb» sm all

i n t e s t i n e o f th e r a b b it d ecrea ses i f the teoperaW re

f a l l s below 25^0 (AuchlnaoFile* ilaoleod and 1 9 3 0 ).

(18)

- 1 0

-InoroAüQd s t a s i s ^ a h l h I n t r a - I n t s s t I n a l

p ressu re dus t o i n j s o t i n • a b lu tio n s in to a 11 atursd lo o p o f Wi@ in t o s t ln o w i l l cisaso alanoromlly rap id

a b so rp tio n <iioDour;all and Vorsar# 1956)» üovsQoiita

o f th e v i l l i coas^ i f tbo blood flo w bsooaso Inadegm te# and :]P@at s tr u o tu r o i ohan os^ J n o lu d ln ^ b leed Inc or

Uosqoaoatlun o f th o ssuooaa» oay ooour In resp o n se to d istu fb a n oea in th e b lood flow #

The problaa undertai:(Ri in th e p resen t vortc la th e oeeaurecient o f tho ^mte o f o b so rp tio n o f omlno 'a c id s from th e sm all i n t e s t i n e and tlie c o r r e la tio n o f tW s e r e s u l t s w ith t ! » c o r n s ponding o o le c u la ^ welf h ts and

apparent m olal voltases» i or th o study th e two speolas^

r a t and o a t , have been ohoaen»

b ) >truoture and h is t o lo r y o f the n u ti

The acm ll I n t e s t in e i s e s p e o ia lly

(19)

• 11 •

otruob TP#* aXthc^^-h sh o # ia 0 0 2m dlffmrmioQm* 1# .

#vop^^h#p^ t)n an# In p rln o lp l# * ao «bat on# doaoPips tioei a p p ll# 3 to t i l l o f tiy%a# ?bo taaln fu n ctlon a o f tho acm ll in te a tin # a re (a ) the forim rd ln g o f th#

I

oJiÿsxta ûlonr i t o oo'jpae* (b ) th e oont^nued «lîgaatlon

o f tho ohyae by means o f s p e c ia l J u ic e s 3 0 0 '#t#d by

i t s walk's end by th e aooeasory glands* and (c ) àbaorps

t lo n o f th e liq u e f ie d n u t r i t i v e m t e r i a l in to th e blood and 1 oph v e s s e l s ;

:>urfao# o f th e muooua ciectoraaai

Ttxi uurfaoe o f the mueooa m3mb:»@no in th e jtooaoh* in v ^ c h ab sorp tion la In a l n ifio o n t * d oes n o t show any o u tir o c th a j In tb o iz sa ll in te s tin e ^

fpoQ udiich th e orranism r e o e lv e s alm ost a l l o f i t s food o a t e r i a l ; th e su rfa ce i s enortaoaaly Inoreasod through

th e format ion o f o ir c u la r fo ld s * and the v i l l i (P is* 1)#

The fo ld s are co n stan t s tr u c tu r e s m û do n o t disappear even uftion th ) in te n t In a l «m il i s d isten d ed # T l ^ b egin about 2 em; from th e pyloru s and rea ch th e ir maximal development in th e d i s t a l Im lf o f th e duodenum and th e

Ijpoxioal imrt o f th e jejunum ). In tho ileum tîiey 000000

(20)

F If: a. 1 and 13.

I' l n . I la a atero o n lo ro a o o p io vlow o f

the Intoütlxi& l S o h o n a tio . X 17

(21)

O penings o f th e in te s tin a l glands L a m in a p ro p ria

M u scu la ris m u c o s a e L iim p h o id n o d -rtr i n th e la m in a

p r o p ria S u b m u c o s a

iL'ith v e s s e ls ) C irc u la r m u s c le

L o n g itu d i n a l i

m u s c le I

S e r o s a

-L ym p h o id nodule in th e subm ucosa

Villi

Value o f \ K srh rin g L y m p h o id n o d u le

P o r tio n of w ail of «niai! intCHtino; d raw n w ith b in o c u la r m icro sco p e a n d sectio n s. 17 X

after Braus, 1924.

Figure I.

-■i I

S e c t i o n o f a v i l l c s ( c a t ) , . s h o w i n g t h e c l o . s e r e l a t i o n . s h i p o f t h e b l o o d - C A P IL L A B IE S TO T H E E P I T H E L I I M. X 4 0 0 .

r , l o liim n a re p ith p iiia m sse U * , w itli so m e leuoocjft*-» U lw ec n t l a m ; c, b lo o < t-capillary c u t Ic n g th w aj-s ; /, laclpiil. N iim e ro iu s leu c o cT lrs a r c a ls o »<■. ii in tlic t i « « - o l t b e viliu» a n d in t l ie la c te a l,

after Sharpey-Shafer, 1934.

(22)

12 •»

Tho v l l l l arm outf^ow ths o f th o ouoous modhrone ocvQTln ; th o ontlrm stirfaoo o f tho au oosa on the aSdo and croate o f tho f o ld a , a s v o l l a s tho spaoas betwaon

tbam* They ^Ivo too surfaoo a t y ^ lo a l v o lv o ty oppoaranoe^ In th o a d u lt rat thoy aro l o # , f l a t and lo a f-sM p o d ;

In tho o a t thoy a re more o o n lo a l o r f l n - o r - l l k e ( I'lgs#

5# 4 , 0 and 7 )* ih o Inoaaarahlo oponln @ o f th e

I n t e s t i n a l ^lands or o ry p ts o f LiebeMmtn may bo seen between tlie b ases o f th e v i l l i ( P i g . 7 ) .

T M _oi^ltholiqqi

The e p i t h e l i u n , to io h co v e rs th e fr e e su rfo o e o f th e taooouj aortorano* to e su rfaoo o f the v i l l i and s o a l l a re a s beto^on t h e ir b a s e s , i s sim ple oolucmar# ih r e e tyi^es o f c e l l s can bo d io tin -^ ia h e d lii i t * - (a ) sim p le ooluonar e p i t h e l i a l c e l l s )aith a s t r i a t e d , c u tio u la r border I (b ) r o b le t o e l l a ; (o ) olirocaaffine c e l l s .

(23)

F1p:3, 5 and 4.

F in , 3 shows tb s hlatoloG loaX Appearanoe o f

tho uppor loop of tho sm a ll in t o s t l n o o f tho oat In transvorao s e c tio n a f t e r im lf Isosm otlc I'lyoino bad boon l e f t in tho lumen o f th e gut fo r 43 m in u tes. The v l l l l are long^ f in g e r -l ik e p r o o o sso s. There la no apijoront In ju ry to th e Qplt e l l a l o e l l s o f th e v l l l l , X 0 ,

I 'lr . 4 shows tho h l s t o l o r l o a l api^ooranoo o f the upper loop o f tho sm a ll I n t e s t i n e o f the oat a f t e r h a lf Isosm otlc l y o l n e had been l e f t In th e lumen o f the r u t f o r 40 m in u tes. The ep ith eliu m o f the v l l l l l a a b s o lu t e ly

(24)

Figure 3

(25)

/ / ■ i

8 a 6 .

r i n . s ohowa tiia h la to Io X ^ rlo a l appoarj tonoo o f a tranavorso s e o t io n o f a t y p ic a l ra c îo n o f the upper loop o f the jm a ll

i n t e s t i n e o f the r a t a f t e r h a l f iaoom otlo g ly c in e had been l o f t in th e lumen o f the ju t f o r 1 b ow # iJSnoe tlio v l l l l o f th e r a t are l e a f shaped # In tr a n s v e r s e s o o t ion s they a r e r a th e r lik e mounds than lo n g p rocesses#

X 14#

i If^# 6 aho\98 th e v i l l u s o f th e r a t w ith

(26)

•g ajnSij

M:6I li3;D i^ 3S-/2idjD L |S j 3 y D

U l r

•< iM .i.> :ii\i >’iH > ^;iA -ii'M p-i;r t i . i . t u i.\ ;i m ' l ' n i \

(27)

Fl<:8# 7 end 0.

I""!/;» 7 ahnwa a X on ritu d liial s o o tlo n o f the jejunum o f th e o a t (aecai dla^Twamatio) d e p ic t in g th e varlou o ooeto o f th e omaXl

in t e o t in o * X 4D#

(28)

i.ithi ikuhu musruUtri» muiO'-it

IIP

inltTTt UMUluT

\ , r . SK C TIO N O F T H K SM .M.L IS T K S T IN K ' ' 'O " ''

after Shorpey-Schofer, 1934.

Figure 7.

after Mottram, 1922.

(29)

• IS

-oXod9 ocxm^otlOF] o f %h^ e p ith e lltm w ith t h9 oorm aotlve

t is s u e * In the l i v i n g o o a â ltlo n * G ibbet end 8 Lmoo@@$fully th e Sitm .tr airigln^ from the movenfmt o f th e ^ 1 1 1 m â th@ tBOohanlaal e o tio n o f th e p arsin g food m te^ lo X * In

'oath* homv^Vp th e o o m o o tlo n l e ea s! l y d ootroyod and I t I s e s t r e c n ly d l f f l o u l t to p rosorve the t? u o I n t r a v lt a l c o n d itio n s In f ix e d n m torlai# 6 f t o r f i x a t i o n th e o p lth i e llu m , a s a r u le * appears detaohod from th e stroma on

th e yuamlt o f tlio v l l l l In e oontlnuoua la y e r and ft

sm a lle r or la r g e r oavlb y I s aeon jotooon t h e two t i s s u o a .

io h lo t o a l l a »

G oblet o e l l a a r e so a tto r o d between t h e o y lln c ir lo ftl e p i t h e l i a l o e l l i * They Ovicwr on the f r e e su rfa o o aa

w a ll 03 In th e orypta# They are s i n g l e c e l l s and bhoir s id e s are convex by reascm o f th e proaauro o f th e r^ clg a n s and push away th e neighbouring ooltm nar o e l l s *

Crypta o f bleborUuhnt

The e p ith e liu m o o v o r ln i the v i l l i c o n tin u e s

In so the glands o f ^ leberkdtn* iV^ove t h e bottom o f

th e cryp t t b e l r w a lls a re lin e d w ith an u n d iffe r e n tia te d * low oolujanar e p ith e liu m whlc^ oon taln o nxaaerous m ito se s# tîero r s veneration ta k e s p la c e and the new c e l l s taovlng upwaN g rad u a lly d i f f e r e n t i a t e In to ^ o b le t c e l l s and

(30)

„*» 14 •

In tho botî&oa o f ube rlan d j o f Li^b^rlsiU» in t h i sm a ll i n t io a t in i, tbQ ./^ o u lia r, l&a», @ o o l l o o f PanOuh occur r o j u 3 o r lj # T bolr n u o lo i ay* l a r j e and

roundod; tsliolr fr*)3 odi,:a ojuo^ilaso I j f u l l o f lurj® cp iio rio al a ^ ld o u lilllc :j?an u lo j, and t*hoir proxizaal

oy^oplaaa c o n ta in s b a s o p h illo ircxa - o o n ta ln ln g

o îiro a ld ta l oubsta. 0 9 *

;i:;,^ooarrin9 c o l l a i

Jhrosaafflno oolXa a r e th e raroau* They w o

aoro abundant In ttio diiodontan than oltîaei* tho jojun^sa or iloum ond a ro found botw eon tbo o a lla l i n i n g Uho

zlandu o f Lloborkulzi*

In th e m iddle o f v i l l u s la a ly a p b a tio v e s a e l» knoon ao th e c e n tr a l l a s t e a l « « i l loh nay be

on lark ed n ear I t s coaom oem ont; tbm en lar, oaent i s

roplaoad Ir 30s» a: Ixaals by a network o f æ m ll v o a s e la . SfirroundInr th e l a o t o a l are f i n e b un d les o f p la in

m uscular t i s s u e prolon^^^od from th s csusoularia aucoaae# À netwoi^c o f b lood c a p i l l a r i e s (F ig s* 2 and G) l i e s

(31)

- 15 •

o f tho v l l l u a .

*ho lüzalntt i^ o p p îa o f t?ho muooua aDsabrano f i l l s a l l tiho 3^41093 a o t 'joon uho land a o f î^loborklili and f o m a Uba ooro o f tjho v i l l i #

0 Qat;ü o f th o m i l *

Tho 9uiX3ucou3 la ^ o r oonalst^o o f lo o a o o o m o c tiv o

ülaaua# In thn ’UodoauQ it» la ocouplod by a t»hlok

la y or o f d a - landa f ^ m n o r ^ h lo h send ù b oir

duo tu to tk 4 In iisr ou rfa o o o f tbo oaoouo raoiabrono botvioon tb s cr y p ta o f Llsberkdlm o r In to tUoa»

The e x t n m a l lo n g it u d in a l scid th o I n te r n a l o ir o a la r la y or a o f tba au scu l.jrt.3 e x te r n a (F ig # 7 ) a r e m i l devolopod In th e em a il I n te o tla e # The e x te r n a l o o a t o o n a ia te o f a la y e r o f œ a o t h e l î a i o e l l o r e a t ln g on l o o s e e o n n e o tiv e tlse m e # th e se r o sa # A t th e a tta o h s ment o f th e m esentery^ t î » serou a la y e r o f th e I n t e s t ln o a

cm itin u ea on to th e s u r fa c e o f th e m ea en tery .

;vb3Qgotlvo a c t i v i t i e g i

The c o lo2 2r>ar o e l l a b ear t h e burfion o f th e

(32)

•» X O '

co n ten ta # Tbo 'îpîth^lltjra o f tho m aall Intoatîîno

ôdsaXfcn TiatïTP aiul m in era l a a l t s , tâvi pro<3uot3 o f dlreutlO D

o f oa^)obydra^Ao ond ^ata#

^h@ Gmisio a o ld a , nbXoh are a p l l t p ro d u its o f th e p r o t e in s , a r e b l diffuai'oX e^ e n te r (^Alokl^ mid cannot be observed in t r a n s i t beoauao onr caiorooheniaaX te a ta

are n ot a u ffio le n tX y d e l i o a t e ; a lt e r a t lw io in c o l l duruotare

h a v e, ho s e v e r , been rep orted # éiaoklln and (1986)

!Ave 3ho«n v& ouolatlon end aveXXlnc o f tlie oelXa a t the t lp 3 o f th e v lX ll durtuG p r o te in abaorption to be an a -o n a l o r earXy p o s t mortoo plionomenon.

^ f t e r a b so rp tio n th e aubatanoeo e ü e r th e t la sue f l u i d on th e o th e r s id e and a r e tak en up by th e blood v e s s e l? and lym p iiatioa. The c a p i l la r io a form a vez^ d en se n e t wo in th e lam ina p r o p r ia , o r ->:>re, o f the v i l l u s * The lyiapVatioa h ere se r v e a double f u n o t iw * In a d d itio n t o d r a ln in Wie t i s s u e f l u i d , a s they do e ls e w h e r e , th ey ta k e up th e absorbed f a t ; henoe th e s e s tr u e t u r e s a n k n o w a a tW XaoteaXa* In th e d isten d ed s t a t e th eu e are th e l a r e s t stx^iottures in th e v i l l i *

o ) t i l g ^ o r i o a l r e v i e e t

(33)

X7

-two a a în l i b o a . I t nmy

\rt

oappoaod «Itliarr* t!mt

a'osorptilaT from th a in t o a t in a io a p h y sic a l or

i)hy8ico*«K»c^AT^ioiil ro o a ss or sZiat tîm pro ca s 9 o f

in t » 3 t iim l a oaorp tio n l a , in p a r t , a t cgiy r a t o , &n a c t iv e p h y a lo lo g ic a l funotlcm o f tho a p î t b o l î a l e o lla #

(1308) (potOS Ü p p o o ra to c (B* *403^"3?7)

aad l a l e n (^#L. 13^«200) oo proponndW tlm e a r l i e s t

th e o r ie s oti tho 0 0 chan io n o f ab sorp tion # The l a t t e r

b e lie v e d th a t a b so rp tio n occurred throu ;h o r i f i c e s in th e blood v e s s e l s , p a r t ic u la r ly th e venous blood su p p ly, in th e i n t e s t i n a l o o l l #

Kudo 1 phi (1 3 3 3 ) and i^iapandle (1025) %mre omon^iat th e f i r s t workers to hold th e view th a t p:i^'3ical "iaUib; i t i o n ° was th e ca u se o f a b so rp tio n # A lso e o o iv s t th e e a -* lie st recorded vlm#s on a b so rp tio n was th a t o f

Biedeaiann m ô -molin (1 3 2 )) aho oom;)arod th e ab sorb in g v i l l i to in v erte d seo-^etln : lan ds# - 1 t h th e odvenoe o f knowled ] 0 o o n o em in ; osm otic phenomena, P iso lier ( 1 8 ^ )

and D utrooW t (1326) ex p la in e d th e p ro cess o f i n t e s t i n a l a b so rp tio n by th e th eo r y o f endosmosic# ^rüdko (1351s 1 3 ^ } , boweven, s t i l l upheld fâ» h y p o tlie s ls form ulated by Liebm^kuhc (1745) th a t th e predominant f a c t o r in i n t e s t i n a l &b3orpti<%i u»3 n i t r a t i o n # The tf^iory

(34)

18

-o f bkn v i l l i vîh-oncse tbay #-o 'O up oy übo

blood voaaala# Xlyj ao&lon WJ aald to bo o .a o f

f i l t r a t lor of oc»ntont3 of tm ln to 3 tl,io j j

prosauro thi>.->u db tbo gut imXi Izito tM voao^la o f tlB

v l l l l # do til Lloborkulm oxiù 3rüok@ b o lto v o d th at tljoy

had obsirv'^»! oponln^a Into tho v l l l l # tbvlonoly, suoh

o*5ndltlono w o ld load to o b llto r a tio n o f tho o u p llla rlo o

and lo o ta eIs and^ I f f i l t r a t i o n ooouri*od at a l l ,

flu id s oxpt*0330d TDUld ^û33 Into tho :)orltoroal oavlty

and only v^ry s i 3^htly into tho blood or lytaph#

V o lt and iauor (10G9) u#&pld t h i s view fo llo w in g o b se r v a tio n 3 on tho a b so rp tio n o f p v o to ln a o lu tlo n o ,

jem m , and s a l t s fro© th e I n te s tin e # -boy oon d n d ed th a t f i l t r a t i o n brought about b y l n t r a # l n t o s t l n a l o r o o sw e

«aa r e s p o r a îb îo fo r I n to :tI n a l ab sorp tion and m t oaoosla# 'The30 d ed u c tio n s ?oro founded j a r t l j upon th e orrozieoua

id ea th a t the pas aero o f s o lu t io n s through tho in to i t In a l ^%all should im ita te the d i f f u s i o n o f t h e sac^ s o lu t io n s tlirouph a r t i f i c i a l nocD ones# The f a c t th a t an In a l

:coA)ranos may vary in t h e i r p o rm o a b lllty ^ms n o t knoun a t the t io 9 #

(35)

X9 •

In f u o t f i t probable from t&o work o f Ludwig

(1351)

and înv^ôtl7<ôtlons cm tho h l a t o l o ^ o f tb@ -u t m i l by rijckm (1354)^ r io lllk w (1D50) end

ai'td S t iln a c h ( 1 3 ^ ) tibat sotaa s p o o ia l o ^ ll a c tio n vma

c o n o o m ^ In tW proooas o f & Jsorption« ülX^r bad#

liidaod# as o a r ly a s 1041 Jeo larod th at th@ c y l l M e r o o l l s dl30cv4f.»d by H^nlm (1027} axsrtoC in 1^9 pSKJO^as o f ab aorp tlor an ®oï*{anîâbô Analwbmns® (o r g e n lc a tty a o tio m )* !iop 9#'^oyl9T (1£31) waa feh9 f i r a t to raaintain d e f i n i t e l y th a t I n t e s t i n a l ab so rp tion m a a f a r o tlo n o f ttie l i v i n g e p i t h e l i a l c e l l s * The evldeno© taas haaeC upon the

a c t io n o f tW / u t in oh-olera end poison ed by c a p ta in t o x ic 3Ubetanc93* Sl^boe# in th e s e oases» nor^aal

ab sorp tio n did r o t oocur ^loppe^ e y l e r oonaidored ubat the "’v i t a l ” a c t i v i t y o f th e I n t e s t i n a l c e l l s had been impaired* In o b o lw a # «bora th e ^ i t h o l i u n o f th e

i n t e s t i n e i s la r g e ly s:ieJ^ the ah eorp tion I s a t a Jwand* s t i l l a lth o u ^li th in n in g o f th e laec^raoe m ight favour osm otic t r a n s f e r o f the g u t oontcm tJ. * ss^taoufsh ^eld

(1 9 3 0 ) p o in ted out th at th e s e e^pe ^im^Tits d id n o t n eo esss a r l l y prove th a t th e epltbm llum ocG lvoly t ran i f erred th e

(36)

2) ^

d i f f u s e ovmr Into tbn no th a t tly* volu o o f tb n lr

ozm otlo preaanr 1 aa a f a c t o r in aooorptiorz o f :m tw

Î3 onrajll^td’’.

<2 ) :rM3o Til "forIt;

Holdonliain (1394) and l i i s p u p ils Leubusoher (1 3 3 5 )4, Cumll^'^kl (1S8G) miô ^bl-rmm (1037) oame t o tbo

38130 oonoluslori arj th a t o f -iop:)0^ i j l i r ^ h ot vrlth oao la o d lflo a tlo n * Hoidonbaln b^lavc»3 th a t a o o rta in p o rtio n

o f tho 3olv«mt and a o lu to a^sofbod o siio sla *

Another p ortion imo ahaorbod b y th e p h y a lo lo ^ io a l a o tltr lty o f the llv ln ,'; e p i t h e l i a l o e llo and <343 not obey th e knomx p h y s ic a l la w s , Heldonhain saaiutaiiiod th a t by th e

^ a c t iv it y o f th e liv in g s ooH** th e c e l l oould e x e r t aa iiifl'îô n o o upon i t s p h y sia a l o r oljflEdoal proooaoaa#

Cohribeim (1398 -1933 ) absorbed t h a t th e prooooe

o f a b so rp tio n jaaj a one-way neohanlom# 313 S r m s tlp a tlo n a le d h la to th e d e c l s l o r u hat, undei^ noi^aal 0 0 nd I t i o n s ,

a p p r e c ia b le amounts o f c llfT u s ib le blood o o n a tltiie its d id n o t pass In to th e in t e s t in e # I n t a s t ln a l absorption^ uooordSns to Cohnh''lm*3 th eo r y Involved two f a o t o r c i -( 1 ) or. It^ p e m e a b lllty t o body f l u i d s and d is s o lv e d îTJbatflEicas due to th e a c t i v i t y o f tlie c a p i l l a r y

(37)

« 21

( 8 ) an a l l l b y o f m i l t o tolm up th o

o n to n ta fpoa lt»a lumen tli*ou;h th e in to rm o â ia tlo n o f t t o v i t a l G o tiv ity o f th e (^ I W ie lia l c e l l s , a lU n otlon a h a o lu te ly f r e e o f p ljy slo a l Iri'lnonooa# T h is h y p o th e sis* th e p o fo r e , d if f e r e d from th a t o f lioidenhoin in th a t i t r e je c t e d th e Idea o f c e ll u la r a o t i v i t y o f th e ep itliellu B i belnr a f fo o ted by th e osm otic p ressu re o f th e in t e a t In a l oo n ten ts#

ayaouth Held ( 1092*1912) on th e acme ;;;enoral rounds a a . ^eidenhain end Johnheim ooDeluded th a t

i n t e a t l n a l a b sorp tion was due to th e i^ y s io lo Q io a l a c t i v i t y o f th e e p i t h e l i a l o o lla * Ilo sta te d * however* t h a t th e forma o f ener^iy u t i l i s e d in th e c e l l u l a r mechanism ware n o t o th er than th o s e k n o w in th e p h y s ic a l world# Be a so irn ed th e power o f ahaorption e n t i r e l y t o c e l l u l a r a c t i v i t y and oonaequaatly h is th eo r y waa in c lo s e r a

ment w ith ohnheia than w ith uoSdonhain p o stu la te d

th a t osm osis played some p art in th e prooeas o f ab so rp tio n # aymouth e ld (1898 a*b . ) based h ia c o n c lu s io n s on th e

e v id en ce o f a s e r i e s o f experim ents where a b so r p tio n o f serum from th e I n t e s t i n e under c o n d itio n s in wl^lch the p u rely p h y s ic a l fo r o e s o f f i l t r a t i o n * om oosis* and a d so rp tio n wore exclcided# îie showed thut o p e r a tio n s

(38)

— 22

e p ith e llo Q 3topp«>â tails a b s o r p tiv e p ro ce ss# In : a o t# any o o n â ltlo n depressJn:; the a c t i v i t y o f tb e c e l l s te id o d to redu ce the a c tio n o f etosorptlran# By ooans o f a

d if f u s io n ap )aratua c a lle d an o s o o o e te r end an I s o la t e d

' r

s u r v iv in g p ie c e o f I n t e s t i n e a s a m^xahraoe aymouth A e ld dosons tr a ted In 1892 t l » t movement o f sv ^ sta n o es took p la c e a c r o s s th e :^ndt>reno# The aovenent took p la c e from th e f l u i d In CK'^ntact a l t h th e mucosa t o th a t bath ln ^ th e o p p o s ite s e r o s a l s id e o f th e In to t in e # Oomotlo p ressu re I n flu e n c e s he ixnaoved by u s in g f l u i d s o f th e 3ome com position on e i t h e r s i d e o f t i e noobrane and In t h i s manner, i t v a s a r u e d , tlie a c t iv e fo r o e o u s t be a v i t a l fu n c tio n Inherent In th e e p i t h e l i a l o e lla # waymouth ffeld (1 9 )1 b ) v e r i f i e d Gohnholra’ s f in d in g t h a t th e p ro cess o f a b so rp tio n was a one««ay meci^anlam* The r e v e r s e p ro ce ss o f raovoment o f su b sta n ces In to th e r u t lumen mas sa id t o r e s u l t from c e l l u l a r In ju ry o n ly , in e h lo h ca se tho o e l l s l o s t t h e i r ^ o r ie n tin g ootion®#

In 1992 wayoouth eld d e v ise d exp erim en ts t o d etm m ln e th e e f f e c t o f Intravenous I n ja a tlo a s o f sodium c h lo r id e

on th e a b so rp tio n o f g lu c o se from th e I n t e s t in e # ïio .

jhowed th a t the de o f ^ a ter ^mssare from th e I n t e s t i n a l s o lu t io n was n ev er Snoi^aaml under c o n d itio n s o f

(39)

•• 23 4#

ohlor*îâ03 aoov^ th e n^^naal amount he b e lie v e d th a t th e uptake o f w ater fx*oa a s o lu t io n in th e in t e s t i n e » wliere

th e ep ith eliu m was uninjured» was n ot a sim p le fu:x^tion o f o a o o tlo iv ea o u re o f th e sodium c h lo r id e o f the blood# He oonoluded th a t aa t h i s waa th e c h i e f Dlood s a l t i t was

n ot l i k e l y th a t any o th e r b lo o d c o n a titu e n t could i n f luonoe the a b so rp tio n o f f l u id from tâie in t e s t i n e #

*ho work o f th e s e th r e e a u th o rs provided the b a s i s f o r t4ie theory th a t t î » p h y s io lo n lo a l a c t i v i t y o f th e

i n t e s t i n a l c e l l s was r e s p o n s ib le f o r a b so rp tio n from th e in t e s t in e #

bambur^^ (1000 - 1034) opposed th e tlieo ry t h a t th e a b so rp tio n prooesa was duo t o '’v i t a l ” c e l l a c t i v i t y # From a s e r i e s o f aKperlizi%ts in ten d ed t o e s t a b l i s h th e

e f f e c t o f i n t r a - i n t o s t l n a l proa su re upon a b so rp tio ii he ocxieluded t h a t a ltb o u :h z^hyalologioal end ^ atliolo i e a l changes cou ld a f f o o t th e p h y s ic a l fo r o e o in v o lv e d th ey d id n o t ce a so t o be p u rely læ oîm n ioal# Ue found t h a t

inoreaaed in tra ^ ^ in testin a l i^ressuro f a c i l i t a t e d aboorptlon^ a f a c t a lreo i:y e s ta b lis h e d by Loubusoher (1085)» and

b e lie v e d th a t th e i>itra*in t e s t I n a l p ressu re which would aH o;: o f a b so rp tio n was low er than th a t o f th e i n t e s t i n a l c a p i l l a r i e s » how mu oh low er i t ml h t b e depended on t h e fo r o e o f t i n p ro cess o f ir a b io itio n and th e ”suokinc®

(40)

^ 24 •

aX30 ir eluded th e “auotlon'* and p ro a a w o a o tlo n o f the v l l l l a s w e ll aa fo r o ea o f osm osis and f i l t r a t Iwi# lie clai^ned to have im ita ted a l l th o phenomena e x lilb lta d

In th o i n t e s t i n a l a b so rp tio n o f ioôSxm c lilo r ld o and ovQc o f serum w ith a r t l f l o i a l l y o o i^ t n oted ooc&>ran9s#

nober (1800 • 1014)» cson^parinr: th e r a te o o f

d lffu s lo r i o f v a rio u s s o lu t io n s o f s a l t s vAth t h o lr ap^eâ o f ab so rp tio n In th o I n t e s t in e » oonoludod th a t a lth o u g h th e p h y s ic a l fa o to r a p lay a p art In tho ooolianista o f a b so rp tio n they did n ot f u l l y e x p la in th e %Aol@ prooesa* So was ccnvl-noad th a t s a l t s were absorbed In to th e

i n t e s t i n a l c e l l s o n ly I f th e y tn r e l i p id s o lu b le * T h is a T eed w ith the worlc o f O v ertœ (1007; 1 8 9 0 ), # :o postxA t ated th a t lip o id s o l u b i l i t y determ ined o e l l p erm ea b ility * I t was on t h i s b a s is th a t ^icber exp'»alned how t h e

o p l t l i o l l a l o e l l a uohsved towards d is s o lv e d su b ston oes l i k e o th e r o e l l s * l i s s o l v e d substanoeo h avin g a

p a r a l l e l r a t e o f a b so rp tio n and jpeed o f d l f f u i l w i wore l i p o i d I n s o lu b le end passed between tâie c e l l s * 3t!ier ta a te rîô lo liavlng a greater r a te o f a b so rp tio n than o f d if f u s io n were l i p o i d s o lu b le and passeri through th e

c e l l s * 'îôber b e lie v e d t h i s th%xry to be n o t in o o n s l s t m t or oonf n o t i n g w ith any osm otic e x p la n a tio n o f the prooesa* Zhls co n cep tio n r e le g a te d a vory In o i ;n iflo a n t r o l e t o

the e p i t h e l i a l o e l l s In th e l i v i n g anim al and a

(41)

• 20

in l i p o i d0 xma33iBted b y any othar* f& otor would# aa

iioora (1921) has statocl# r m sa lt In th a a o w m u la tlo n to s a tu r a tio n p oin t o f tho su h stan oos in q u e stio n in th e l i p o i d s o f tho t i s s u e s and oould n o t accou n t f o r th e ste a d y stro a n o f r lu ld s though tho o p ith ^ litw t th a t ooours durinr ab so rp tio n *

a lla u e and .ushny (1G0B| 1899) o mparod tb s r a t e s o f a b so rp tio n o f a la r c o nuohsr o f eq u i^ o lo o u la r

s a l t s o lu t io n s w ith a 1^ fv ) sodium o h lo r ld e s o lu t io n and found t h a t th e r a t e s o f a b so rp tio n d id n ot oor r e spend w ith th e d if f u s io n r a t e s * S a l t s «h ioil were e a s i l y

d ls s o o ia te d in t o io n s bavir^; threat speed wore n o t a Iway# absorbed f a s t e r than s a l t s l e a s eauil;,' d is s o c ia t e d and whose io n s poaaesood low er sp e e d . a l l a o e end v ehny d ecla red th a t tiieao f a c t s d id n o t n e o e s o u r ily in d ic a t e th a t th<% e p i t l i e l i a l o e l l s opm^atoc; o n ly by a v it a l ^ a c t i v i t y end that i t waa more l iU e l y tâmt tlie p r o c e ss o f a b so rp tio n was due to a c h e o io a l r e la t io n o f c H o ld to

s a l t s o f such a n a tu rs t h a t tlie c m ll mlr.ht ta k e up one s a l t e a s i l y and r e j e c t a n o th e r .

e)

ivbsorption o f suf:arat

I t was th o c a r e f u l stu d y o f tho a b so rp tio n o f th e asn osaooh arid os e ^ c h le d o v o n tiia lly t o th e s o lu t io n o f tho problem Which 1ms d iv id ed th o cK^ohanlsts and

(42)

*■ 26 •»

ttiatp a lth o u h knom p b y a lo a l law s are fi&otors o f (jpoat liqportar^oo lu p roooss o f a b so rp tio n # tb sy oannot e x p la in a l l tho ^^xmoooRa oonoomod w îth

a b so rp tio n » ^ o rl usod i^mnaostb@11 sW r a t s a s hi s oxperixasntal on n a i s . Ilo d s to m ln o d tho r a t o s o f absorption o f nonosaooharldas from tb s sm all I n t e s t in e by fe e d ln r a known anoLint o f a Iv e n sunar in s o lu t io n

throurli a stoo aoh tubs# k i l l i n g th o o n lc m l, end e s tim a tin g th e anouTit o f su^rar remain inn In th e î n t o s t l n e . lie was a b le t o d o te m ine w ith T o a t aooupuoy the esnount o f aucar absorbed in a riven tim e by a r a t of îmoan w e ig h t.

i t h l n f a i r l y wide lim it a # th e amount o f lu o o s e absorbed d id n o t vary w ith th e o o n o a n tra tlo r o f th e s o l u t e . In

o th e r words# th e p ro ce ss o f a b so rp tio n d id n o t o o n fo m to th e law s o f d i l ' f u s l w and o sta b sis. I f absorpticxi was m erely a m atter o f d i f f slo n th e nuaho^ o f Ion s bombard In c th e obaorbii f’ su rfeo e In u n i t tim e would o b v io u s ly be a f a c t o r o f g r e a t Im portance.

- C a r l’ s method o f d etG roin in g tho r a t e o f a b so rp tio n o f aonosaocîm ridea g o ffered frp a one d e fe a ts namely

the n optyin g tim e o f the stomach was v a r i a b l e . To overcome t h l j# V e r a ^ (X 935| 1330) 1 ije o te d tfte auger

s o lu t io n s d i r e c t ly in t o lo o p s o f the s n a i l i n t e s t i n e o f a n a e s th e tis e d r a t s . i l » amount o f sugar remoinia;-

(43)

- 27

-end rm a n lta . ^ t h Qo@^mr@ found tlm t

1i9%oeo8 3uoh a s glu co a o and naXaotoao a sort^ad a t

a lauoh fasfcai* r a t a from tho sm all In to ? tln o o f tho r a t than woro pontosos suoh a s x y lo s o end a ra b ln o eo . I t tîas p o stu la to d hy V s r a ^ th a t th s d lffo r o n o o în t?.o r a t e o f a b so rp tio n o f hoxoeos end p o c to so s In tho s : » 11

I n t e s t in s o f tho r a t was duo to a s p o o la l a c t i v i t y o f tho i n t e s t i n a l nsoosa# namoly î^ a p h o r y la t lo n o f tho lioxoaoa*

^vldonco fo r t h i s th eo ry # hswevor# I s n o t

oonolualvo end a p p lie s to ;ho r e t o n ly . end

%lr& (1937) p o stu la te d th a t th e y e f o r e n t l a l ^ s o r p t i o n o f z^luoose d e o r e a se s aa one p rofv easo a towards th e

oaudal end o f th e s m a ll i n t e s t i n e o f t h e r a t and th ere# f o r e th e phosphorylatlnc: iseohanlao was more a c t i v e In

the o r o n la l reg io n o f tho nut# However# la v ld s o n and arry (1 9 4 ) ) found th a t w ith in (Aie oaudal h a l f o f th e sm all i n t e s t i n e o f th e oat th e r e was no evldonoo o f d e o r e a sln a b so r p tiv e power f o r gluooao in th e more d i s t a l region #

f ) a b so rp tio n o f f a t s #

(44)

• 28

-ürmnaport d lffo r u fv o n t5 » t o f p r o to in or

(mrbobzyidratf) ùranoport în th a t t l » f&tfcy aolda» tb e elQiainbal o o a s t l t u ^ t j or th o f&t» aro I n s o lu b le in

a to r A3 a e a lo o most o f t h e i r ocvmpoiinda^ it iile th e ooxvespoîiüiîi^ oloQOiita o f /apoteln #L:M3 ^orbohydrate e r o r e a d ily ^ t e r - o o l u b l e #

^‘hare a re ulyeo t h e o r ie s ea to ho*^ f a t * l e I n s o lu b le in iw tar^ osn pass tbo e p ltU o llic i o f th e au ooea, n a r e l y j d ) th a t f a t ol^/bt bo d is s o lv e d in tho l i p o i d s o f

th e o e l l s a f t e r s p l i t tin(^ in to f a t t y a c id s « > ^ ile th e ly o e r o l a i r h t b e absox^bed by i t s e ^ l b i l i t j in ;m tor ( leidonhaln* 1380) • Iloeever* f a t t y a o ld s a re ^ ir a o tlo a lly n o t aasorbad ohon Inti^^duoed alan o in to an ea p ty

I n t e s t lim l lo o p . T heir l i p o i d s o l u b i l i t y i s fa r to o s l i g h t t o a l l o e tliem to d i f f u s e In to Wie e p i t h e l i a l c e l l s in any r e a t q u a n tity # (2 ) th a t f a t s so f i n e l y

e a u l s lf l e d by tlw b i l e th a t tW f a t d \ ) p l 3 t s m ight b e a b le to a s s tlie e p i t h e l i a l <iall and n > u tra l f a t appear a g a in In t h e lyc^T iatios (Wmik# 1 8 ^ ) # A m eohonical fo r c e m 3 onoo su g g ested to e:<plain the eu tranoe o f th o se f i n e d r o p le ts in t o th e e p i t h e l i a l c e l l s b u t improved

h l s t o l o g i o a l tech n iq u e has a/.om # i l s to be q u it e

errim eou s. (3 ) in ID ol P flu g e r opposed t h i s liy p o tW sis# end put forward a new th eory o f f a t a b so rp tio n # lie

(45)

- 29 •

Tba f a t a a m w by l i p a s e In o f b i l e

In to f a t t y a c id s and - ly o e r o l# 3 1 y o o ro l l a gater*# s o lu b le and d lf f u o o s m a d lly ^ and. th e f a t t y acld a a re s a p c n lfle d by the 3 odium carb on ate o f tW p o r o r e a tio

and I n t e s t i n a l j lo o s#

i’ho aa ln d lf f io u lt r r fb r tho th eory a m s o «hen th e a o tu a l r o a a tlo n o f tho I n t e s t i n e e a s te ste d # Pfluj^er 3peaâ:3 o f the a llr a lln o r o a o tlo ^ o f the I n te s tin e ^ but as a m atter o f f a c t , a lth ou gh th e p a n o rea tlo Ju lo e îias a pH o f 8 or rjom . I t l e q u la k ly changed b y th o I n t ^ i t l n a l co n te n ts# K oatyal (102 0) s tu d ie d th e o f the I n t e s t in e o f r a t s , d o g s , ju in e a p ig s and p ig e o n s , o ’p e o l a l l y fo r t h i s parposo end found i t to bo so ld o u rroato^ than pB7, and gon-*rally under t h is v a l u o , l# o # In th o a cid pogton# Icb ln so n (1936) fbund a r e a c t io n o f pHG#5 In th e

duodonum o f r a t s , and i)H7#0 „ G a t tho I l e o c o l i c v a lv e * 2h i s ezclu d ed th e p o a c l b l l l t y th a t f a t s tforo aosozW d In th e f o r a o f a l l m l l soaps#

A ccordin'; to V orsar (19 36) th e f a t t y acld a

eoablned e l t h th e p aired b l l o a c id s to forta ocopounds# which ar^ n ot o n ly w ter##8oliib lo and d i f f u s 3ble # b ut a ls o e s p e c i a l l y s t a b le at tlie s l i g h t l y a cid r e a c tio n

(46)

5)

-adsorbed ooto sraooaal e p ith e liu m ao that th e y ^jore a b le to d ia j o lv o a auoh r e a t e r q u a n tity o f f a t t y aoid:3 than in v itr o #

The f a t t y a cid « îilo h vfao r o e In th e c o l l combined 5 lt h tho tlyooT O l, « îiich tmo ahoorbed a t thD aaao tim e , to reayn tho a ls o n e u tr a l f a t # This c y n th e s ia jasboA

through an I n t o n e d l a t e e ta ^ e o f pboapîm tîdo form ation# The ly o o *ol uao phoopborylatod and o^obîned i7ltb th e

f a t t y a o id s# Thus th e d i f f u s io n .r a d ia it In to th e o e l l s fo r th e f a t t y a o ld s »aa Inoreaaed# s y n t h e s is o f n e u tr a l f a t , v ia th e f o r a a tlo n o f p h o sp h a tid e, uaa

tija refo re art a o o e le r a tln y f a c t o r In the a b so rp tio n o f f a t i Just a s the phesphoryl& tion o f jlu ooa e Q coelerated - th e a u s o r p t lw o f t h i s su^sr#

In th o m ucosal ep ith e liu m th e p liosp h atlâe v a s tronsfermod s - o i n in t o n e u tr a l f a t an d , fo r the most p a r t , appeared as suoh in th e lyoph# S i ^ i f l e a n t hut varyin g amounts escaped tho tr a n a fo n a a tio n , and apiioared in th e lymph aa p hosp h atid e ( l e c i t h i n ) , and so In creased th e l e c i t h i n co n te n t o f th o blood d u rin g f a t abaorptloci#

(47)

51

-I t îma shown by wu5f»r anâ (1958)

tb a t a f a t $ su ch a s t r io l e i n ^ ^as o n ly p a r t i a l l y d ig e s te d in th o i n t o i t i r o by tho m n oreatio ju ic e * ?^ydroî/sÎ3

d etoraln od th e path taîter by th o absorbed! f a t t y m a t o r ia l, th e f a t t y acid f r a c tio n pass in ; by th e p o r t a l v ein to th e liv e r ^ and the unliydrolyeeC p o r tio n by th e lym phatic r o u te in t o th e ay3te*T!io blood* and %ienoe to th e f a t depots* î l i l a ccMriaeption la con trary t o th e p r e v io u s ly aooeotec! h yp oth ea la o f Voraar* î^ore r e c e n tly * in a re v ie w o f f a t ohsorpticxi#

r a s e r (1 9 4 )) a rain aen tiosied th a t n o t a l l o f th o f a t in th e I n t e s t in e aosorbod a s f a t t y as id s and ^ ly c e r o l* b u t th a t a t l e a s t soLie o f i t was absorbed a s e ^ su lsifie d fa t^

i . o . a s t in y p a r t i c l e s o f f a t or o i l * He based h i s ovldm'ioe in part on obaorvationa o f tlie f a t p a r t i c l e s p r e se n t in blood# These a r t i c l e s * c a lle d "chylotalorons” can b e oo’snted under darkfleXd illu m in a tio n # An I n t e r e e t ia g argument in fa v o u r o f th e a b so rp tio n o f e m u ls ifie d d r o p le ts o f o i l i s th e f a c t

tlmt

p a r a ffin o i l I s n ot o r d in a r ily absorbed, but I f i t l a e m u ls ifie d by th e a d d itio n o f sm a ll a so u n ts o f o le io a o id and c h o lo a te r o l* th%i I t l3 token in t o th e I n t e s t i n a l

wall

(Iraa ar*

te w a r t, and Schulman, 1942)* I r a s e r eod M s co-w orliers were

a t a l o s s

to

understood how p a r t ic le s o f f a t o r o i l ^ tnioron in diam eter could fl" ^ t h e i r v#ay in t o tlio inteutl^^al c o lla #

however* lopao (195?; 1943) and ‘Copac and '>hanf)ers (1957)

(48)

32

-»6Ss) and f o r p lan t o e l l s th a t I f an o i l y d r o p le t Î3 plaoed

In co n ta c t e l t h tb'3 c e l l rmi>r^un^ tlv5 o i l w i l l ra I d ly e n te r th e c e l l I n t e r i o r . " '^ a ls if lo a tlo n o f f a t s in th e I n t e s t i n e I s favou red by b i l e s a l t s and th e s e s a l t s tend to '-'ako f a t t y o o ld s n ore s o lu b le , lliu s th e b i l e bas an ltar>ortant I n flu e n c e on f a t absorption#

(g ) iw 3or::tior o f main:- a c l d s *-^

r e s e n t v le ^ s on n a tu r i o f aninr; g o ld s In s o lu t io n : S ln o e u a ts r undergoes i o n is a t io n w ith p ro d ro ti :icm o f hydrogen Ion and Ttyd o x y llo n . I t w i l l a c t b o th a s

an a cid and as a a lk a li# T his prorjorty i s a ls o ?iet w ith in the. c a s e o f many o th er oomixwads whsn d is s o lv e d In w a te r , and which are t!:ep ofore six>ken o f a s am photeric e l e c t r o l y t e s or an p b olytes# The amino a c id s a r e s o æ o f tlie moat

Ix ^ w ta n t o f t h e s e .

A c e tic a c id , wh<m d is s o lv e d in w ater under "oes io n is a t io n to a sm a ll extend w ith produo t io n o f hydrogen io n s ; i t th s r e f o r e a c t s a s an a cid # I f tSbo assiao

;;roap ( W Hg) i s Introdtioed in t o m o le c u le , a a in o -a o e tio a c id o r

Glycine,

Cîîg (BHg) GOJH, i s o b ta ir e d ; and t l i i s

cjoaiX3unci, in sc lu t i e r , oaixiot o n ly yielx: hydrogen io n , c a t in v ir t u e o f th e p resm o e o f th e group, oan a l s o ,

throu ;h r é a c tio n w ith w ater g iv e

(49)

- 55

a lk a lis * m a l aa e oaao ^Rlvin ; rn lta

w ith û c lâ a , o . GHg Cr)3Ü» îîCl)« i^a in th e oaaa o f

a l l a:ip^3olyt‘^:., ^ io n isa tio n Uakea plaoo on ly to a s llr ^ t s& tw t$ an that lyaln o whavoa a s a vopy wsak a lk a li

and a v^ry woak acid*

Acoord Inc ^ cic>2*o v iew s m ;ardlnr a Ida and

b a ses ar ocipholyto I s a su b sta n ce ifihlch om\ a o t b o th a s a

^)Totc^ donor and a s a proton aooep tor* Thus in tlio c a se

o f aqueous s^iXutions o f rl^ oin o* f^Iîg GH^ one may nave

tho r o a o tlo n s :

f i f l r . OHr, CO O H ;;= ± n n C H „ )0 0" h- H*" o r

a ^ a " +

and j.n i ^ BU* dH O i h + J'd op

B a* + OH'

C lyoln e may th oroforo y i e l d b o th a c a tio n o% d an onion#

b ln o e an OQpholyto oiku o o t b o th a s ari u o ld ond a base I t w i l l ha VO an a c id Ic siia u tlo n cons ta n t K a a s vvoii

0 3 a b a sic I o n is a tio n co n sta n t ( a lk er* 19b4 o^b#) The

oorre:3po d in e moss las? eq u aticu a ore*»

^a * L ”1 s?lxM?o H” i s tl50 Ion BH^OE^,G >9 or

(50)

m 34

D

M

& ]M

Î3 t b i o a t Ion )!^# i'be c o n s ta n ts K. mtd K bavo

t- 2 a &)

boon oûlculGt^O rî»02î c io to n a im tio iia o f tljo Jo r@o : f

h yd roiyu la o f tho com pounds o f t2jo ta^pliolyte w ith stroirs a o ld a and w ith atron r m oos, and from maasuromonta o f th o oOk'jJuctlvity o f s a l t s o f th o am oW lyto. *Ito va liiaa so ob tain ed f o r

a o v ir a l o f tlio amino a c id s a ro v o iy s m a ll, b o li : about

XO"^ - 13-1 fr y ana 1)"^^ - 13*12 fpp Sltsoa ttho

amino a c id s may b e r'»oi*dod a s a a b stitu to d d o r iv a t lv e s o f e o o t lo a d d and a-?nonlum \xjÛvoslô^ « h ich Imvo io n is a t io n oo n atan ts ab %3t ocp al to 1«B x 11**^, an aooo ta n c e o f t h e s e low f ir ^ r e s f o r Him amino a d d s ira o llo s a trmcmndous 1 flu e n o e o f the s u b s titu e n t rou p s on e X e o tr o ly tio d is s o c ia t io n *

i t

noticed bg JJerrun ( 1925 ^ that by aa strains

the uncîiarr.ed traction of the colno add to e x ist mostly in

the form of d-uUly

^witterionon or dipolar Ions,

(tb5 %)rd awittor is

eiiua. to m for a liei^mplïTodito),

much mere reas nablo vcluos for th^ oo. star:to cf the aaino

acids

oould

be obt&lred from tho ooao oxperiaentul d ata#

Therofors

x^efers to

dlasocutdon of tho I

-^roup and

the loalaatilon z»olati no are do crlbou by tlio e q u illl^ ia ,

■*'eh,cii, c 53H * ;.;l .;:„C33" + s * w ? ' +

(51)

• 35

Hgl + 4- OZ" or jg'

f o r whloh tho nasa l a ’s- o/..Ti@$3 on3 a r o i

-\ * C a i —L z iJ ’t . - b n ' J . L i - J .

^ and

M

I?-]

^ v ld o ^ tl^ 3060Tir=mort3 t^^îoh 7 5 old valtios f o r fÇ, o f ^ alk or»»

th o o rj :^lli iv o v o l' 1 0 8 f o r K o f Shoory end

%3oa3uro30nt3 , Ivin^ w i l l a ls o Iv o Tho tt?o oota o f

conatcT.ts aa’* m l a t od b y I d e n t if y in g ^ and sln o o sa ch r e f e r s bs^o to th^ t o t a l e l e o t r l c a l l y n e u tr a l am pholyte,

i f th e eq u ation s doflnlnr^ . K end Ky^TJ a re s r o lt le lle d to^ etlier*. W a s a n th ose d e f in in g K and K , I t f o llo w s th e t T K. «

^ a &% L)

K,K , These oroduots ere eq u al to th^ lo^ rrfx^^'Ot o f « a te r

' w f 8

s in c e j^Oir^ Y.^+ f o r any s o lu t io n so

d ilu t e th a t th e a c t i v i t y o f u n io n ised m t e r smy b'» taken a s u n its * In th l? end o th er taass la i eq u a tio n s th e b raok eta r e f e r to the TRolnl corcon tratIon ^ and Y to th e a c t i v i t y ODCfî I c lo n t o f th e Ion or m o le o u le . At v er y l o r ooncenj t t r e t l o n e a l l a c t i v i t y c o e f f i o i e n t a ai>proaoh u n it y and a c t i v i t y ten d s to become id e n t l o a l t^îth th e m o l a l i t y .

Tha d e s ir e d r e l a t i o n s oro* th er efo re ^ E Z Eu ©rid i ! r

E . » ,\g . The a d van ta jo o f tho E m itter ion s y s fn n I s th a t I t Iv es reore '^eae n a b le t^alues t o the 0 0 s t in t s ^ # i i o h

(52)

- 36

In 3 u f f îcîfn iîsly a c t s 3 0 Î a tio i3 , feho sn în o a old la

p o s i t i v e l y on o l o o t r o l y s l s ml;;pat03 to tho

otithode, ah9?9U3 In s u f f l o l e i t l y a lk a lin e s o lu t io n s I t la

n o,3ativaly obar^^od and nl^Tûtoo to th o on od e. ^b^loxisly

th ere lauat bo a d o f l n l t e hydrogen io n cono ont r a t io n at nî:loh i t n i j r a t o s n o îtb o r to th e anode nor to th e OEithodo. T h is I s oelloci th e I s o o l o c t r lc p o in t . '’^ ch o sln o a c id has a a p a o lfic î a o e lo o t r îc p o in t . -o have a l l p r o t e in s . I t m&a o r ig l: : a lly - hcra^ht th a t a t I t s i s o o l o c t r l o p o in t , an asiirso a cid was n ot d isa n o la to d e i t h e r ao an acid or ca a b a s e ,

i^^kooorjln,: to th e Z w ltto rlo n îiy p o th o sls , th e amino a c id tsoloou lo i s e l o c t r l e a l l y n e u tr a l a t t&io I s o d b o tr lc p o in t , but t h i s

n a a t r a l i t y la due to th e com plété and sltsn lta n eo u s I o n is a t io n o f a c id and b a d e r o u p s.

The fa c t th at ir o te in s c o n sist o f amp^iotorio «usine

a cid s i s o f r e a t Inportanco in iotoria?oting nany o f th o lr

r e la t io n s .

3ober and -iobor

1 37) found anlno acids to

be eboorbod at a hlrtnr rate than could bo onpeotod f*roo

tlioir calculated nkolecular volnmi

end

oron at a M her rate

oonsidoriii " the voluno of tho swlttorions of t?io ampholytes

b ein g

enlarge

' by a

sh e ll

o f

tmtir dlpoleo.

t^ie other

References

Related documents

At present in some Member States data from ministries or from trade associations are used to compute short term statistics. 9 ) Following the principle of subsidiarity, this

International Journal of Scientific Research in Computer Science, Engineering and Information Technology CSEIT1726324 | Received 01 Jan 2018 | Accepted 09 Jan 2018 | January February

frame mode encryption ,motion vector difference. encryption and residual data encryption which

Daher wurde jeweils Ende März 2008 und 2009 Gelbsenf zwischen die Spargel-Dämme gesät, mit dem Ziel, entweder die Schnellkäferlarven aus den Dämmen anzulocken

Abstract —Chiral sorbents for HPLC separation of optical isomers carrying glycopeptide antibiotics (eremo- mycin or its eremosaminyl aglycon, ristomycin, or vancomycin) fixed onto

This thesis provides an in-depth analysis of a range of 3-D shape descriptors for their suitability for general purpose and specic retrieval tasks using a publicly available data

of the plot, b) the “filled” and more symmetrical funnel plot including the imputed studies as mirror images of those on the left hand side (open circles). Solid line

Pasture availability and 'utilization' 69 Pasture Composition 73 Pasture Strata Composition 79 Animal extrusa Composition 85 Pasture Composition : Animal Diet Composition 90