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Influence of hyperbaric oxygen treatment on cerebral resistance vessels reactivity in diabetic rats

The incidence and mortality of ischemic stroke is higher in diabetic patients compared with non-diabetic patients (1). Previous studies on diabetic animal models as well as in human confirmed that vascular reactivity to various stimuli in diabetes mellitus is significantly impaired (2, 3). The aim of this study was to evaluate effects of hyperbaric oxygen treatment (HBOT) on vascular reactivity in response to several vasoactive stimuli, in isolated pressurized and perfused middle cerebral arteries of Sprague-Dawley (SD) male rats by videomicrometry. There were four groups of rats ; control (n=12), diabetic (n=12), diabetic rats that underwent HBOT (n=11) and control rats that underwent HBOT (n=12). Rats were exposed to HBOT at 2, 0 atm, in duration of 120 minutes for 4 consecutive days. Diabetes was induced by single dose of streptozocin (60mg/kg i.p.). Rats where 12 week-old at the time of experiment, with 6 weeks diabetes duration. For statistical analysis One way ANOVA was performed (Sigma Plot 11.0). Results showed significantly decreased vasodilation in response to hypoxia (p<0, 001) and acetylcholine (Ach 10-6 mol/l) (p< 0, 014) in diabetic group compared to all other groups, and restored vasodilation in response to ACh and hypoxia in diabetic rats after HBOT compared to diabetic group. Vasodilatation in response to NO donor DEA-NONO-ate (10-6 mol/l) (p=0, 931) was not significantly different among groups, suggesting that during 6 weeks of DM vascular smooth muscle cells kept its ability to respond to NO by relaxation. Vascular response to vasoconstrictor serotonin (10-6 mol/l) (p=0, 983) was not significantly different among groups. In conclusion, our results demonstrate that hyperbaric oxygen treatment leads to restoration of vasodilation in response to ACh, but does not enhance vasoconstriction in response to serotonin, suggesting beneficial effect of HBOT on vascular function and tissue perfusion.

hyperbaric oxygen; acetylcholine; serotonin; middle cerebral arteries

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