Plasma osmolality

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The sensitivity of the human thirst response to changes in plasma osmolality: a systematic review

The sensitivity of the human thirst response to changes in plasma osmolality: a systematic review

Given the integrative nature of these homeostatic mech- anisms, could a patient ’ s own subjective sense of thirst be a better guide to the need for further hydration than our current clinical assessment? The degree to which clini- cians include assessment of thirst when considering fluid prescription is not known. Anecdotal evidence suggests that some more experienced clinicians may do so. How- ever, the value of this may be influenced by the degree to which thirst reflects a dehydration-related rise in serum osmolality. Perhaps thirst is one of the few sensitive symp- toms of underlying reductions in total body water, and should prompt further clinical and biochemical investiga- tion. If so, this might guide fluid administration in hospi- talised patients, fluid being delivered until thirst is no longer present. However, before such practice can be rec- ommended, it is essential to quantify the diagnostic accur- acy of thirst so as not to pose a risk of iatrogenic dehydration or fluid overload. To explore the feasibility of this approach, we performed a systematic review to deter- mine the value of plasma osmolality associated with devel- oping a sense of thirst, how this relates to age and gender, and those factors which might influence thirst in hospita- lised patients (Fig. 1).
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Interferon-alpha is a predisposing risk factor for carbamazepine-induced hyponatremia: A case of syndrome of inappropriate antidiuresis caused by interferon-alpha therapy

Interferon-alpha is a predisposing risk factor for carbamazepine-induced hyponatremia: A case of syndrome of inappropriate antidiuresis caused by interferon-alpha therapy

The basal AVP concentration relative to plasma osmolality was below the normal range in healthy subjects (Figure 1), and it was suppressed by 50% with water loading performed 19 days after starting interferon-alpha 2b injections (Figure 2). Plasma ANP levels decreased after water loading (Figure 2). One year after discontinuing interferon-alpha 2b therapy, while still taking CBZ, warfarin potassium, and bucolome, a second water-loading test showed that the minimum plasma sodium and osmolality values obtained 4 hours after water loading were higher than those obtained at the time of the fi rst water-loading test, but they were still lower than those in healthy subjects (Figure 2), and they were accompanied with a nonsuppressive sodium concentration and osmolality in the urine. The cumula- tive urine volume excretion increased more than during the fi rst water-loading test, but it was still lower than in healthy subjects (Figure 2). The baseline plasma AVP level was higher than it had been during the fi rst water-loading test, and it was not suppressed after water loading, while the plasma ANP levels at baseline and during water loading were normalized (Figure 2).
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Development and Clinical Application of a New Method for the Radioimmunoassay of Arginine Vasopressin in Human Plasma

Development and Clinical Application of a New Method for the Radioimmunoassay of Arginine Vasopressin in Human Plasma

correlated significantly with both plasma osmolality (r=0.52; P<0.001) and urine osmolality (r=0.77; P<0.001). After fluid restriction, plasma AVP was uniformly normal relative to plasma osmolality in patients with nephrogenic diabetes insipidus and primary polydipsia but was distinctly subnormal in all patients with pituitary diabetes insipidus. The infusion of physiologic amounts of posterior pituitary extract caused a dose-related rise in plasma vasopressin that afterwards declined at the expected rate (t½=22.5±4 min). We conclude that, when used appropriately, our radioimmunoassay method provides a useful way of assessing AVP function in man.
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Key points in Diabetes Insipidus´ Diagnosis

Key points in Diabetes Insipidus´ Diagnosis

When an increase in plasma osmolality is detected by osmotically sensitive neurons (osmoreceptors) located in the anterior hypothalamus, AVP is liberated. This increases resorption of water in the renal collecting tubules, stimulating thirst. The increase in ingested water reduces plasma osmolality to levels at which the control of urine production mediated by the increase in AVP maintainsosmolality within its normal range [5,6,8]. CDI may becongenital, and may have a genetic cause. However, it is acquired in 95% of cases [9,10]. Familial CDI is the most common genetic form. It has a similar incidence in both sexes and most frequently presents as a progressive deficiency in the secretion of AVP. Acquired causes include any surgical, traumatic, ischemic, infectious, or infiltrative lesion or tumor in the hypothalamic-hypophyseal region leading to destruction of AVP-producing neurons or impeding transportation of this hormone by the pituitary stalk [5,10,11]. Several tumors of the central nervous system may cause DI, but craniopharyngioma is the main etiology. Other tumors that may cause DI are germinoma, meningioma, glioma, and astrocytoma [5,6,10,12,13]. Cranial trauma resulting in pituitary shaft contusion may be a cause of DI [14]. Transitory DI is the main complication of transsphenoidal surgery [15]. However, craniotomies in which neoplasms are resected often result in permanent DI [5]. The main infectious causes of DI are meningitis, encephalitis, sellar- and super-sellartuberculomas, and infection with cytomegalovirus or neurosyphilis [5,6,10,16,17]. Other causes may be lymphocytic hypophysitis, aneurysms, thromboses, Sheehan syndrome, and multiple sclerosis [5,6,18-20].
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Molecular cloning and differential expression of the glucocorticoid receptorgene in the estuarine tapertail anchovy Coilia nasus.

Molecular cloning and differential expression of the glucocorticoid receptorgene in the estuarine tapertail anchovy Coilia nasus.

After simulated transport, the survival rate decreased to 73.0% in the non-NaCl group (Figure 3A). NaCl (1.0%) was then added to the transport tanks to reduce the death rate caused by stress, and there were no dead fish in the 1.0% NaCl group (Figure 3A). When the plasma osmolality was determined in both groups (Figure 3B), it differed significantly between the non-NaCl and NaCl groups (P < 0.05). Plasma osmolality was significantly elevated after loading (0 h), but then decreased significantly in the non-NaCl group. Unlike the non-NaCl group, plasma osmolality increased significantly in the NaCl group compared with the control fish, but was maintained at a level similar to the control level after loading.
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“Essential” hypernatremia due to ineffective osmotic and intact volume regulation of vasopressin secretion

“Essential” hypernatremia due to ineffective osmotic and intact volume regulation of vasopressin secretion

A physiological explanation for sustained hyperosmolality was sought in a patient with histiocytosis. During 23 days of observation with only sodium intake regulated at 100 mEq daily, elevation (mean 310 mOsm/kg of water) and fluctuation (range 298-323) of the fasting plasma osmolality were recorded. The presence of endogenous vasopressin was indicated by the patient's ability to concentrate the urine to as high as 710 mOsm/kg of water with a creatinine clearance of 84 cc/min, and by dilution of the urine in response to alcohol. The failure of increasing fluid intake to as high as 6.2 liters daily to lower the plasma osmolality indicated that deficient fluid intake was not solely responsible for the elevated plasma osmolality. Hypertonic saline infusion during water diuresis resulted in the excretion of an increased volume of dilute urine. The water diuresis continued despite a rise in plasma osmolality from 287 to 339. An isotonic saline infusion initiated during hydropenia resulted in a water diuresis which continued despite a rise in the plasma osmolality from 303 to 320. Stable water diuresis induced during recumbency by either oral ingestion of water or
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Flow along the Gut and Intestinal Absorption of Salt and Water in Euryhaline Teleosts: A Theoretical Analysis

Flow along the Gut and Intestinal Absorption of Salt and Water in Euryhaline Teleosts: A Theoretical Analysis

The parameters are: drinking rate Vo, plasma osmolality Opl, maximal NaCl absorption rate/ Namax , concentration at half maximal flow CNaj, osmotic permeability coefficient Pos, and solu[r]

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Ionoregulatory changes in different populations of maturing sockeye
salmon Oncorhynchus nerka during ocean and river migration

Ionoregulatory changes in different populations of maturing sockeye salmon Oncorhynchus nerka during ocean and river migration

enzyme activity that occur in seawater are probably preparatory for movement into freshwater. Uchida et al. (1997) also suggest that physiological and histological changes in the gill of chum salmon are preparatory for upstream migration. These authors showed that gill Na + ,K + -ATPase continued to decrease in maturing chum captured before river entry and held in seawater; chum held in seawater showed elevated plasma osmolality and increased mortality. Although physiological changes in seawater appear adaptive for river entry, there is also evidence that hypo-osmoregulatory function is directly impaired in sexually maturing adult salmon (Clarke and Hirano, 1995). Changes observed in seawater salmon may be associated with elevated reproductive hormones. Endocrine factors associated with maturation impair ionoregulatory ability in seawater (Lundqvist et al., 1989; Madsen and Korsgaard, 1989). In a parallel study, an increase in reproductive hormones for Fraser River sockeye tagged in Johnstone Strait was found before entry into freshwater (S. J. Cooke, S. G. Hinch, G. T. Crossin, D. A. Patterson, K. K. English, M. C. Healey, S. Macdonald, J. M. Shrimpton, J. L. Young, A. Lister, G. Van Der Kraak and A. P. Farrell, manuscript submitted for publication). These authors, however, found no significant differences in reproductive hormones among the populations of sockeye, suggesting that differences between populations are not a function of reproductive state.
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FACTORS CONTRIBUTING TO ALTERATIONS IN THE LEVEL OF CONSCIOUSNESS IN PATIENTS WITH DIABETIC KETOACIDOSIS: ANALYSIS OF 189 CASES

FACTORS CONTRIBUTING TO ALTERATIONS IN THE LEVEL OF CONSCIOUSNESS IN PATIENTS WITH DIABETIC KETOACIDOSIS: ANALYSIS OF 189 CASES

Serum osmolality has been found to be significantly higher in unconscious rather than conscious patients with DKA or nonketotic hyperglycemia 1.8. II It has been shown that hyperosmolality impairs function of both central and peripheral nervous system structureS.17.19 Fulop et al. found that altered sensorium correlates best with the magni tude of hyperosmolality, and serious alterations in sensorium with serum osmolality<340 mosm/kg should suggest etiologies other than DKA.7 In a study by Kitabchi et al., calculated total osmolality correlated inversely with mental status, with stupor and coma typically seen with osmolalities of greater than 340 mosm/kg.12 They suggested that when a patient with a plasma osmolality of 340 mosm/kg or less is severely obtunded or comatose, another catastrophic event rather than DKA must be present. Tachibana et al. believe that plasma osmolality between 320 and 350 mosm/kg primarily causes suppression of the pyramidal pathway, plasma osmolality exceeding 380 mosm/kg suppresses the extrapyramidal pathway, and values above 440 mosm/kg cause severe suppression of both efferent pathways.I7·18.19 In this study, although stuporous patients had a significantly higher serum osmolality than drowsy patients (p=0.03), this was not true for the other groups and the correlation was not strong (correlation coefficient= -0.15). All of our comatose patients and all except one of the stuporous patients had a serum osmolality greater than 300 mosm/kg, but only 2 (28.5%) of the comatose and 7 (30.4%) of the stuporous patients had a serum osmolality of greater than 340 mosm/ kg. No other cause was found in two of the comatose and nine of the stuporous patients with serum osmolality less than 340 mosm/kg. In contrast, another cause was found in one of the comatose and 3 of the stuporous patients with serum osmolality greater than 340 mosm/kg. Sixteen of the drowsy and 9 of the alert patients had a serum osmolalit y of greater than 340 mosm/kg.
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Osmoregulation during Pregnancy in the Rat: EVIDENCE FOR RESETTING OF THE THRESHOLD FOR VASOPRESSIN SECRETION DURING GESTATION

Osmoregulation during Pregnancy in the Rat: EVIDENCE FOR RESETTING OF THE THRESHOLD FOR VASOPRESSIN SECRETION DURING GESTATION

Osmoregulation was studied in near term and age-matched Sprague-Dawley rats. Basal plasma osmolality (P osm ) and plasma sodium (P Na ) were 281±3 mosmol/kg and 134±3 meq/liter, respectively, on the 20th gestational day compared with 292±3 mosmol/kg and 140±1 meq/liter in virgin animals (P < 0.001), whereas P urea and plasma water content were similar in pregnant and control rats. These differences could not be reproduced in animals receiving progesterone, estrone, or a combination of progesterone and estradiol for 2 wk. Pregnant and control rats were deprived of water for periods ranging from 0 to 48 h. P osm , always lower in gravidity, was 290±3 mosmol/kg after 2 d of water deprivation in pregnant animals compared with 300±2 mosmol/kg in controls (P < 0.001). Thus 48 h of dehydration were required before P osm in gravid rats was similar to basal values in the age-matched virgins.
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Meal consumption is ineffective at maintaining or correcting water balance in a desert lizard, Heloderma suspectum

Meal consumption is ineffective at maintaining or correcting water balance in a desert lizard, Heloderma suspectum

Our prediction that ingestion of a meal would result in a short-term water cost at all hydration states and that such negative effects would be more substantial in rodent meals was partially supported. At normosmotic and moderately dehydrated states, animals in both treatment groups exhibited a significant elevation in plasma osmolality at 6h post-feeding and it remained elevated for at least 24h. At 48h post-feeding, the osmolality of normosmotic animals remained elevated while the osmolality of moderately dehydrated animals returned to pre-feeding levels (Fig.4A,B). Additionally, consumption of egg or rodent at an extremely dehydrated state failed to improve hydration state within 48h post-feeding (Fig.3), thus failing to support our prediction that meal consumption would improve but not fully rehydrate extremely dehydrated Gila monsters. These results were similar regardless of meal type. Only when osmolality was >350mosmolkg –1 did meal type affect the acute
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Upregulation of aquaporin 2 water channel expression in pregnant rats

Upregulation of aquaporin 2 water channel expression in pregnant rats

Another interesting finding in this study was the persis- tence of the hypoosmolality in pregnancy after 72 h of the V2 vasopressin antagonist administration and comparable AQP2 water channel expression in the pregnant and NP animals. This finding indicates that the hypoosmolality of pregnancy can oc- cur independently of vasopressin-mediated effects of the col- lecting duct water channels. The most likely possibility for this persistent hypoosmolality in pregnancy despite the V2 recep- tor blockade is the polydipsia of pregnancy. In support of this interpretation is the observation that homozygous Brattleboro rats demonstrated the same lowering of plasma osmolality during pregnancy despite the absence of detectable circulating AVP (6, 27). Moreover, angiotensin activity is increased dur- ing pregnancy (28), and the role of angiotensin II in the control of thirst has been well-established (29). Finally, because of the peripheral vasodilation and the resultant arterial underfilling, vasopressin-independent factors such as increased thirst may be more important in affecting water retention in pregnancy than in the nonpregnant state.
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Upregulation of aquaporin 2 water channel expression in chronic heart failure rat

Upregulation of aquaporin 2 water channel expression in chronic heart failure rat

Aquaporin-2 (AQP2) mediates vasopressin-regulated col- lecting duct water permeability. Chronic heart failure (CHF) is characterized by abnormal renal water retention. We hypothetized that upregulation of aquaporin-2 water channel could account for the water retention in CHF. Male rats underwent either a left coronary artery ligation, a model of CHF, or were sham operated. 31–33 d after sur- gery, mean arterial pressure (MAP) and cardiac output were measured in conscious animals, and the animals were killed 24 h later. Cardiac output (CO) and plasma osmolal- ity were significantly decreased and plasma vasopressin in- creased in the CHF as compared to the sham-operated rats. Both mRNA and protein AQP2 were significantly increased in the kidneys of the CHF rats. The effect of oral adminis- tration of a nonpeptide V2 vasopressin receptor antagonist, OPC 31260, was therefore investigated. OPC 31260 induced a significant increase in diuresis, decrease in urinary osmo- lality, and rise in plasma osmolality in the OPC 31260- treated CHF rats as compared to untreated CHF rats. The mRNA and protein AQP2 were significantly diminished in both cortex and inner medulla of the treated CHF rats. In conclusion, an early upregulation of AQP2 is present in CHF rats and this upregulation is inhibited by the adminis- tration of a V2 receptor antagonist. The results indicate a major role for vasopressin in the upregulation of AQP2 wa- ter channels and water retention in experimental CHF in the rat. ( J. Clin. Invest. 1997. 99:1500–1505.) Key words: va- sopressin • vasopressin-receptor antagonists • hyponatre-
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Physical and Biochemical Characteristics of Semen and Ultrastructure of Spermatozoa in Six Carp Species

Physical and Biochemical Characteristics of Semen and Ultrastructure of Spermatozoa in Six Carp Species

Moreover, studies focused on the biochemical composition of seminal plasma of carps species during the spawning season are scarce or limited. Billard et al. (1995) have reviewed the biochemical composition of seminal plasma of some fish. The sodium and potassium levels in the seminal plasma of six carps were high as shown in Table 2 and most probably responsible for the suppression of sperm motility due to their osmotic effect. The Na + and K + levels are known to suppress the sperm motility in jundiá, Rhamdia quelen (Borges et al., 2005; Billard, 1975; Benau and Terner, 1980; Morisawa, 1985). When the seminal plasma ionic composition was compared with the data reported by the review of Linhart et al. (1991) on four salmonid species (Oncorhynchus mykiss, O. keta, Salmo salar, Salmo clarki) and four cyprinid species (Cyprinus carpio, Vimba vimba, Ctenopharyngodon idella, Stizostedium vitreum), it was found that the Na + and K + levels were comparable to our studies. The seminal plasma osmolality plays an important role in spermatozoa activation. The osmolality of seminal plasma was used as a controlling point to develop extenders for semen of many fish species and reversibly suppresses the spermatozoa activation (Ohta and Izawa, 1996). Osmolality of any extenders used for artificial propagation of fish seminal plasma is generally adjusted by the use of Na + and K + levels. Sperm quiescence in undiluted semen occurs roughly in the range of 270-300 mOsm/kg. The seminal plasma osmolality in the European eel has been reported to be in the range of 325-330 mOsm/kg and extenders with this range of values helped in reversibly suppressing the motility of spermatozoa (Asturiano et al., 2004). The glucose content of seminal plasma is also an important biochemical parameter; because it provides membrane protection to spermatozoa and serves as an external cryoprotectant as well (Maisse, 1996). Sugar extenders are also used successfully in African catfish, Clarias gariepinus (Steyn and Van Vuren, 1987; Urbányi et al., 1999). The present study has estimated the glucose level in seminal plasma of six species of carps that may be used for future reference while preparing extenders for carps.
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The effects of acute salinity challenges on osmoregulation in Mozambique tilapia reared in a tidally changing salinity

The effects of acute salinity challenges on osmoregulation in Mozambique tilapia reared in a tidally changing salinity

In both pituitary and gill, PRLR2 mRNA expression increased in FW and TF fish transferred to SW, although the response from fish reared in a tidally changing environment was less prominent. This range of responses could be tied to the changes seen in plasma osmolality, which climbs to much higher levels following FW to SW transfers than from TF to SW. We have previously found that PRLR2 expression in dispersed PRL cells is directly proportional to increases in medium osmolality (Seale et al., 2012b). The significance of this tight regulation by extracellular osmolality may be tied to the involvement of this PRLR isoform in the cellular remodeling of ionocytes required during SW acclimation. Two splice variants have been described for PRLR2, a short non- functional variant and a long functional variant (Fiol et al., 2009). It was proposed that the transient increase in PRLR2 after fish are transferred from FW to SW provides an increase in osmotolerance that supports cell survival during the critical time when the gill epithelium is being restructured for the change in direction of ion transport (Fiol et al., 2009). In the pituitary, however, it has been suggested that PRL secretion may be subject to negative feedback from PRL (Nagahama et al., 1975). Based on the differential regulation of pituitary PRLR1 and PRLR2 by extracellular osmolality, we have previously proposed that autocrine regulation of PRL cell activity through PRLRs may serve to fine tune the effects of PRL (Seale et al., 2012b). Thus, similar to the role of PRLR2 suggested in the gill, the increase in PRLR2 expression in tilapia PRL cells in response to hyperosmotic conditions could be a mechanism to maintain low plasma PRL levels in a hyperosmotic environment.
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A study of predictors and factors affecting outcome in diabetic ketoacidosis patients

A study of predictors and factors affecting outcome in diabetic ketoacidosis patients

The measured serum sodium concentration in uncontrolled diabetes mellitus is variable because of the interaction of multiple factors. The increase in plasma osmolality created by hyperglycemia pulls water out of the cells, and reduces the plasma sodium concentration. Physiologic calculations suggest that, in the absence of urine losses, the serum sodium concentration should fall by about 1.6 mEq/L for each 100 mg/100 mL (5.5 mmol/L) increase in glucose concentration. So, the "corrected" sodium concentration can be approximated by adding 2.0 mEq/L to the plasma sodium concentration for each 100 mg/100 mL increase above normal glucose concentration . 89
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Electrolyte depletion and osmotic imbalance in amphibians with chytridiomycosis

Electrolyte depletion and osmotic imbalance in amphibians with chytridiomycosis

ABSTRACT: Mounting evidence implicates the disease chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis, in global amphibian declines and extinctions. While the virulence of this disease has been clearly demonstrated, there is, as yet, no mechanistic explanation for how B. dendrobatidis kills amphibians. To investigate the pathology of chytridiomycosis, blood samples were collected from uninfected, aclinically infected and clinically diseased amphibians and analyzed for a wide range of biochemical and hematological parameters. Here, we show that green tree frogs Litoria caerulea with severe chytridiomycosis had reduced plasma osmolality, sodium, potassium, magnesium and chloride concentrations. Stable plasma albumin, hematocrit and urea levels indi- cated that hydration status was unaffected, signifying depletion of electrolytes from circulation rather than dilution due to increased water uptake. We suggest that B. dendrobatidis kills amphibians by disrupting normal epidermal functioning, leading to osmotic imbalance through loss of electrolytes. Determining how B. dendrobatidis kills amphibians is fundamental to understanding the host – pathogen relationship and thus the population declines attributed to B. dendrobatidis. Understand- ing the mechanisms of mortality may also explain interspecific variation in susceptibility to chytrid- iomycosis.
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Factors that limit brain volume changes in response to acute and sustained hyper  and hyponatremia

Factors that limit brain volume changes in response to acute and sustained hyper and hyponatremia

proportional to osmolality; (b) brain osmolality remains equal to plasma osmolality; (c) V i is osmotically active; and (d) there is no net gain or loss of solute from V i . The validity of these assumptions is considered. When changes in osmolality are sustained, V i is much closer to control values than when in the acute phase. K content […]

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Drinking Rate and Oxygen Consumption in the Euryhaline Teleost Aphanius Dispar in Waters of High Salinity

Drinking Rate and Oxygen Consumption in the Euryhaline Teleost Aphanius Dispar in Waters of High Salinity

Shehadeh & Gordon 1969 found at higher salinities starting from plasma osmolality an intestinal sodium absorption proportional to the increase in salinity above that of plasma and a high[r]

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Renal function and plasma levels of arginine vasotocin during free flight in pigeons

Renal function and plasma levels of arginine vasotocin during free flight in pigeons

Apparently, flying pigeons experience rises in both plasma osmolality and in plasma volume. These signals would be expected to have opposite effects on the release of AVT (stimulation by increased osmolality, inhibition by increased plasma volume). However, typically, the release of AVT from the neurohypophysis is more sensitive to the former signal than to the latter (e.g. Stallone and Braun, 1986b), and the changes we measured during flight and at rest are consistent with this. The significant correlation between body mass loss (which in flying birds represents mainly water loss; Giladi, 1997) and post-flight AVT levels suggests that AVT concentration (along with plasma osmolality) could be a good indicator of the dehydration state of a flying bird.
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