Influence of acute and intermittent hyperbaric oxygenation on the reactivity of the blood vessels in healthy Sprague-Dawley rats
Mihaljević, Z.1, Drenjančević, I.1
1Department of Physiology and Immunology, Faculty of Medicine Josip Juraj Strossmayer,
University of Osijek, Croatia.
Corresponding author: [email protected]
Key words: rat, hyperbaric oxygen therapy, vascular reactivity, oxidative stress
Introduction: The effect of hyperbaric oxygenation (HBO2) on vascular function has been
intensively studied in last decade and the understanding of the mechanisms of its action has been emerging, particularly in the diabetes mellitus. Our results suggest that repeated exposure to hyperbaric oxygen and the time between the two therapies can be viewed as intermittent pseudohypoxia and it is possible to trigger other adaptive mechanisms than previously observed. Oxygen partial pressure changes may lead to changes in the synthesis of metabolites of arachidonic acid (AA). This preliminary study aimed to examine the HBO2 effects on the
vascular reactivity to acetylcholine (ACh) and hypoxia in aortic ring of healthy rats.
Methods: Healthy Sprague-Dawley 9-12 weeks old rats were divided in four experimental groups (1. healthy control; 2. acute HBO2 exposure; 3. 24 hour after acute exposure; and 4. 4
subsequent days of HBO2 exposure). Isolated aortic rings reactivity to ACh and hypoxia was
studied on Isolated Organ Bath (Experimetria LTD). The indicators of oxidative stress were measured by TBARS and FRAP methods.
Results: Acute exposure of healthy animals (group 2) to HBO2 leads to the impaired
vasorelaxation response to both ACh and hypoxia, not present in the groups 1., 3. And 4. Discussion: Duration of HBO2exposure diversely affects the vascular reactivity to different
stimuli.
Conclusion: Results indicate increased oxidative stress in acute exposure to HBO2, lost in
other HBO2 treatments.
Acknowledgments: This is preclinical animal research, partially supported by grants of Ministry of Science, Education and Sports, Croatia, # 219-2160133-2034 and # 219-0000000- 0328 . All experimental procedures conformed to the European Guidelines for the Care and Use of Laboratory Animals (directive 86/609) and were approved by the local Ethical Committee #2158/61-02-139/2-06.
Comprehensive analysis of ischemic conditioning techniques in a porcine model of acute myocardial infarction
András Makkos
medical student VI., Semmelweis University,
Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary
Corresponding author: Andras Makkos [email protected]
Key words: schemic conditioning, Ichemic postconditioning, Remote ischemic conditioning, MRI, T2-oedema reduction
Introduction: Ischemic pre-, post- and remote conditioning are cardioprotective in animal models of acute myocardial infarction (AMI). However, their effect in clinical trials is still inconclusive, which could be attributed to the difficulties of the evaluation of cardioprotection. Our aim was to compare the cardioprotective effect of ischemic post- and remote conditioning by histological staining and magnetic resonance imaging (MRI) after AMI in a clinically relevant porcine model.
Methods: Animals were randomized into ischemic (Isch), pre- (IPreC), post- (IPostC) and remote conditioned (RIC) groups. In general anesthesia, the anterior descending branch of the left coronary artery (LAD) was occluded for 90 min with balloon catheter (index ischemia). In IPreC group before the index ischemia 3×5-5 min, in IPostC group after the index ischemia 6×30-30 sec LAD occlusion/reperfusion cycle was applied. RIPerC performed by 4×5 min compression of the hind limb.
Results: After 3 hours of reperfusion, myocardial necrosis was significantly decreased by IPreC, but not by IPostC and RIC as assessed by histological staining (Isch: 38.12±6.05%, IPreC: 12.15±2.94%*, IPostC: 38.14±4.89%, RIPerC: 32.43±3.19%; % of AAR). There was no difference in the area at risk (AAR) among groups. As evaluated with cardiac MRI (late gadolinium enhancement) after 3 days, myocardial necrosis was not changed among groups (Isch: 14.34±2.39%, IPreC: 9.01±2.32%, IPostC: 12.47±2.0%, RIC: 14.33±1.75%; % of left ventricle), while myocardial edema (T2-weighted MRI) was significantly decreased by IPostC and RIC (Isch: 30.38±4.05%; IPostC: 18.52±1.80%*; RIPerC: 17.40±2.68%*; % of left ventricle). Microvascular obstruction was also decreased by IPreC and IPostC (Isch: 1.25±0.62%; IPreC: 0.12±0.12%*; IPostC: 0.26±0.15%*; % of left ventricle). *p<0.05 vs. Isch. Discussion and Conclusion: In our translational model the T2-edema reduction showed the edema can’t define as area-at-risk. The T2-edema reduction with no changes in infarct size can be an independent marker of cardioprotection, as microvascular obstruction reduction. Research support and grants: OTKA ANN 107803; TAMOP 4.2.4.A/1-11-1-2012-0001; TAMOP 4.2.4.A/2-11-1-2012-0001
Acknowledgement: this study supervised by Tamas Baranyai M.D., Ph.D. student and Zoltan Giricz, Pharm.D., Ph.D., senior research associate, Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary
Institutional Animal Care and Use Committee Approval Kaposvár University SOI/31/26- 11/2014
The Role of Oxidative Stress in Development of Impaired Vascular Response Under The Influence Of High Salt Intake in Sprague-Dawley Rats
Cosic A, Drenjancevic
Department of Physiology and Immunology, Faculty of Medicine University of J.J. Strossmayer in Osijek, Osijek, Croatia
The corresponding author: Ines Drenjancevic; [email protected]
Keywords: antioxidative enzymes, flow-induced dilation, high salt diet, middle cerebral artery, oxidative stress
Introduction: This study aimed to determine the in vitro flow-induced dilatation (FID) mechanisms of middle cerebral artery (MCA), the expression of antioxidative genes, genes involved in dilatation pathways, level of leukocyte activation and the role of oxidative stress in Sprague-Dawley (SD) rats on a high salt (HS) diet.
Methods: 11-weeks old healthy male SD rats were divided in low salt group (LS) given standars rat chow (0.4%NaCl) and HS group given food containing 4%NaCl for 1 week with/without superoxide dismutase (SOD) mimetic TEMPOL in vivo. MCA reactivity in response to FID in the absence/presence of inhibitors L-NAME, INDO, MS-PPOH and TEMPOL in vitro was examined. mRNA levels of enzymes from brain blood vessels were determined with rtPCR. Leukocyte activation and level of oxidative stress in leukocytes from blood and peripheral organs were mesured by flow cytometry. Blood pressure, lipid peroxidation products and antioxidative capacity were also measured.
Results: FID was reduced in HS group compared to LS group. Inhibitors (independantly) significantly reduced FID in LS group. FID in HS group was mediated by NO. TEMPOL restored FID in HS group to basal level. Expression of GPx4 and iNOS in HS group was significantly decreased. Antioxidant enzymes activity and BP were not affected by HS diet. HS intake significantly increased basic reactive oxygen species (ROS) production in the leukocytes of mesenteric lymph nodes and splenocytes, and intracellular production after stimulation in peripheral lymph nodes.
Discussion: Mechanisms of FID are different in LS and HS groups. Low GPx4 expression, increased superoxide production in leukocytes, together with decreased iNOS expression underlies increased oxidative stress and reduced NO bioavailability in HS group, which caused impairment of FID in HS group without changes in BP.
Conclusion: FID in HS diet is determined by synthesis of ROS in the vascular wall and affects vascular reactivity mechanisms.
Sources of Funding: This work has been supported in part by Croatian Science Foundation under the project # IP-2014-09-6380 and in part with VIF-MEFOS-15 (Faculty of Medicine Osijek, Croatia).
Acknowledgements: I am grateful to my mentor professor Ines Drenjancevic and to all colleagues from the Department of Physiology and Immunology for helpful advices and assistance during the development of the study.
Ethical Approval: All experimental procedures are conformed to the European Guidelines for the Care and Use of Laboratory Animals (directive 86/609). They were approved by the local Ethical Committee (Faculty of Medicine, University of Osijek; Class: 602-04/14-08/06; No.: 2158-61-07-14-04) and Ministry of Agriculture, Croatia (HR- POK-005).