L-NITROARGININE INCREASES BLOOD-PRESSURE IN THE RAT

1. Effects of administration of N(G)-nitro-L-arginine (NO2Arg), a guanidino nitroarginine derivative, for 1 week on blood pressure and some vascular responses of rats were studied. 2. A significant rise of the systolic blood pressure was observed after the administration of NO2Arg with food (0.023% in weight, about 2.8 mg of NO2Arg per rat per day). Relaxation by acetylcholine decreased markedly in ring preparations of the thoracic aorta of NO2Arg-treated rats. However, glyceryltrinitrate-induced relaxation was not reduced after NO2Arg administration, suggesting that NO2Arg administration specifically inhibited endothelium-dependent relaxation. 3. An increase of blood pressure may be because oral administration of NO2Arg inhibited endothelium-dependent relaxation in vivo suggesting that the release of EDRF is important in physiological control of blood pressure.