| Endothelium-dependent hyperpolarizing factor (EDHF) is the third relaxing factor derived from vascular endothelium besides NO and PGI2. At present, EDHF responses are reported in a wide variety of arteries from different species including humans. One purpose of the present article was to evaluate whether or not there is the role of EDHF in the basilar artery in rats. From the proposed EDHF to now, 20 years have passed, the chemical nature of EDHF was also a puzzle. especially in cerebral arteries, there are still many controversial issues.Endogenous Hydrogen sulfide (H2S) has been shown recently to function as the third gasotransmitter endowed with many biological and physiological functions, It is an important endogenous vasorelaxation factor. It has been preliminary assessed to be of effect of H2S as the same with EDHF. In the present study the partial mechanism of the effects of H2S against cerebral ischemia and reperfusion injury were studied in this paper.Purpose:1. To evaluate the effects of H2O2 and 11,12-EET on EDHF-mediated relaxation in the rat basilar arteries.2. To evaluate the expression of CSE mRNA that is synase of EDHF (H2S) in the endothelial cells of rat basilar arteries. 3. To evaluate the protective effects and possible mechanisms of H2S against cerebral ischemia reperfusion injury.Methods:1. The basilar arteries in vitro were used to observe the relaxation effects to drugs or blockers. In this model it was observed that the relaxant effects of acetylcholine (ACh), Hydrogen peroxide (H2O2), 11,12-epoxyeicosatrienoic acid (11,12-EET), and catalase (CAT).2. The basilar arteries tissue was digested to get a mixture single cell solution by using trysin and collagenase, and the endothelial cells of basilar arteries were purified from the mixture cell solution by using magnetic cell separation system (MACS), and used to detect the expression of cystathionine-γ-lyase (CSE) in the endothelial cells of rat basilar arteries.3. NaHS was taken as a donor of H2S. Focal cerebral ischemia/reperfusion injury was caused by occluding the right middle cerebral artery (MCAO). The numerical data, which were from infarct volume, neurological deficit, brain water content, level of malondialdehyde (MDA), lactate dehydrogenase (LDH) activities in plasma were evaluated. HE staining was used to observe brain pathologic changes.Results:1. In the rat basilar arteries, preconstricted by 30 mmol/L KCl in vitro, Ach (10-7-10-4.5 mol/L) had the concentration-dependent relaxations. 3×10-5 mol/L Nω-nitro-L-arginine- methyl-ester (L-NAME) and 10-5mol/L indomethacin (Indo) could partly inhibit the relaxation of ACh to the rat basilar arteries, but non-No/non-PGI2 -mediated relaxation was still significant (P<0.01 vs Vehicle). 11,12-EET didn't produce relaxation in rat basilar arteries, and H2O2 has little relaxation. CAT could not inhibit the effects of the relaxation of ACh.2. The method of RT-PCR was used to evaluate the expression of CSE in the Isolated and Purified endothelial cells of rat basilar arteries by MACS. It was found that , CSE in the isolated and purificated endothelial cells of rats expressed.3. NaHS(0.195,0.39,0.78 mg/kg) dramatically decreased infarct volume, improved brain pathologic changes, ameliorated the neurological deficit and reduced the brain water content. The activity of LDH in plasma were inhibited, and the contents of MDA were reduced by NaHS(0.195,0.39,0.78 mg/kg).Conclusions:1. Our data suggest that H2O2 and 11,12-EET may not involve EDHF-mediated relaxation to ACh in the rat basilar arteries.2. It was found that CSE in the isolated and purified endothelial cells of rats markedly expressed. These results suggested that production of EDHF (H2S) of rat basilar arteries is existing.3. These results indicate that H2S has protective effects against cerebral injury in rats.
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