NG-nitro-L-arginine attenuates flow debt repayment in the reactive hyperemic response of the open-chest dog coronary artery: contribution of endothelium-derived relaxing factor.
To test the hypothesis that the endothelium-derived relaxing factor (EDRF) contributes to coronary vasodilation induced by myocardial ischemia, we examined the effect of NG-nitro-L-arginine (a potent and selective inhibitor of EDRF release) on the coronary reactive hyperemic response in the open-chest dogs. Intracoronary infusion of NG-nitro-L-arginine at a coronary plasma concentration of 5 x 10(-5) M had no effect on hemodynamics and myocardial oxygen metabolism, but attenuated repayment of the flow debt by an average of 20.4% and 20.0% following coronary occlusion for 10 sec and 20 sec, respectively. Concomitant infusion of NG-nitro-L-arginine at the same concentration and 8-phenyltheophylline (a potent adenosine receptor blocker) at a coronary plasma concentration of 10(-5) M further attenuated flow debt repayment following 10 sec and 20 sec of coronary occlusion by 47.7 and 59.4%, respectively. These results indicate that EDRF plays a significant role in the coronary reactive hyperemic response and may cause vasodilation independently of adenosine-mediated vasodilation following coronary occlusion.
Marutani
M
M
First Department of Internal Medicine, Okayama University Medical School, Japan.
Kusachi
S
S
Kajikawa
Y
Y
Yamasaki
S
S
Tsuji
T
T
D000241:Adenosine / Q000502:physiology; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives* / Q000494:pharmacology; D003331:Coronary Vessels / Q000187:drug effects / Q000502:physiology*; D004285:Dogs; D017202:Myocardial Ischemia / Q000503:physiopathology*; D009569:Nitric Oxide / Q000502:physiology*; D019335:Nitroarginine; D010101:Oxygen Consumption / Q000187:drug effects; D011453:Prostaglandins / Q000502:physiology; D013806:Theophylline / Q000031:analogs & derivatives / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects*
D011453:Prostaglandins; D019335:Nitroarginine; D009569:Nitric Oxide; D001120:Arginine; D013806:Theophylline; C028322:8-phenyltheophylline; D000241:Adenosine