The Relationship Of Hydrogen Sulfide To EDHF-mediated Relaxation In Rat Middle Cerebral Artery Precontracted By U46619

Endothelium-dependent hyperpolarizing factor mediated vasodilatation is a non-NO, non-PGI2relaxation,and it plays an important role in the resistance artery and small vascular vasomotion regulation. Hydrogen sulfide was considered to be the third new gas signal molecules,and it has the important adjustive effect in cardiovascular function. Our previous studies show that DL-propargylglycine (PPG),a H2S synthase (cystathionine-y-lyase, CSE) inhibitor could significantly inhibit acetylcholine (Ach) induced non-NO, non-PGI2relaxation on rat middle cerebral artery precontracted by U46619, and it showed the correlation between H2S and EDHF. The present study was further to study the the relationship of hydrogen sulfide to EDHF-mediated relaxation on rat middle cerebral artery precontracted by U46619.Purpose:1. To observe the EDHF-mediated dilation in rat middle cerebral artery.2. To study the relationship of hydrogen sulfide to EDHF-mediated relaxation on rat middle cerebral arter precontracted by U46619Methods:We apply the method of vosomotion function measuring to measure the function of rat MCA. Segments of the middle cerebral artery,which is about5mm long,were dissected,and superfused the inner artery cave, then preconstricted them by10-7mol/L U46619-Until the persistent constriction,add the corresponding drugs into the infusion,measuring and recording the diameter of vessel under microscope.Results:1. In isolated rat middle cerebral artery that precontracted by U46619, Ach (10-7-10-4.5) had a concentration-dependent relaxation, the Ach-induced vasorelaxation was significantly inhibited in the presence of3x10-5mol/L L-NAME and1x10-5mol/L Indo, and the left relaxation was abolished by1x10-7mol/L CTX and5x10-7mol/L Apa together.2. The non-NO,non-PGI2-mediated relaxation was also abolished by10-4mol/L PPG.3. NaHS, a donor of H2S had the concentration-dependent relaxation at the range of10-5～10-2.5mol/L in rat middle cerebral artery precontracted by U46619, and the vasorelaxation was obviously abolished by1x10-7mol/L CTX and5x10-7mol/L Apa.4. L-Cys, substrate of H2S led to a concentration-dependent relaxation at the range of10-5～10-5mol/L in rat middle cerebral artery. But the relaxation was almost abolished by1x10-7mol/L CTX and5x10-7mol/L Apa or remove endothelial.Conclusions:1. There is the EDHF-mediated relaxation in rat MCA2. The so-called EDHF dilation in rat MCA might be mediated by H2S.