title: Captopril restores endothelium-dependent relaxation of rat aortic rings after exposure to homocysteine.
abstract: This study was designed to investigate the effects of captopril, an angiotensin-converting enzyme inhibitor, on inhibition of endothelium-dependent relaxation induced by homocysteine in isolated rat aorta. Isometric tension recordings were used to assess inhibitory effects of homocysteine and protective effects of captopril on endothelium-dependent relaxation of aortic rings. Exposure of aortic rings to homocysteine (0.3 approximately 3 mmol/L) for 30 min induced a significant concentration-dependent inhibition of endothelium-dependent relaxation response to acetylcholine (ACh), but did not affect endothelium-independent relaxation response to sodium nitroprusside. Pre-incubation of aortic rings with captopril (3 approximately 30 micromol/L) for 15 min and co-incubation of aortic rings with homocysteine (1 mmol/L) for another 30 min attenuated the inhibition of homocysteine in a dose-dependent manner. Moreover, superoxide dismutase (SOD, 200 U/mL), a scavenger of superoxide anions, reduced homocysteine-induced inhibition. L-Arginine (3 mmol/L), a precursor of nitric oxide (NO), also attenuated the impairment of vasorelaxation induced by homocysteine. However, in the combined presence of SOD and L-arginine, the inhibitory effect of homocysteine was reversed, which was very similar to the effect of 30 micromol/L captopril. These results suggest that captopril can prevent the inhibition of endothelium-dependent relaxation induced by homocysteine in isolated rat aorta, which may be related to scavenging oxygen free radicals and enhancing NO production.
mesh_terms: D000109:Acetylcholine / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000493:pharmacokinetics; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects* / Q000503:physiopathology; D001120:Arginine / Q000493:pharmacokinetics; D002216:Captopril / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000503:physiopathology; D006710:Homocysteine / Q000009:adverse effects* / Q000037:antagonists & inhibitors / Q000493:pharmacokinetics*; D008297:Male; D009126:Muscle Relaxation / Q000187:drug effects* / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D013482:Superoxide Dismutase / Q000493:pharmacokinetics; D014664:Vasodilation / Q000187:drug effects
chemical_list: D006710:Homocysteine; D001120:Arginine; D002216:Captopril; D013482:Superoxide Dismutase; D000109:Acetylcholine