Cardiovascular regulation by L-arginine in the brain of rats: role of the brain renin-angiotensin system and nitric oxide.
The effect of brain L-arginine on arterial pressure was investigated by injecting L- or D-arginine into the cerebral ventricles of male Wistar rats that were anesthetized with urethane. Intracerebroventricular (I.C.V.) injection of 1 micromol L-arginine reduced the arterial pressure and the abdominal sympathetic nervous activity (SNA), whereas the injection of 10 micromol L-arginine induced a transient pressor response and reduced both the heart rate and SNA. Although I.C.V. injection of 1 micromol D-arginine had no effect on cardiovascular function or SNA, injection of 10 micromol of this enantiomer elicited a transient pressor response, similar to that induced by 10 micromol L-arginine, followed by a persistent increase in arterial pressure and a corresponding increase in SNA. I.C.V. pretreatment with the nitric oxide synthase inhibitor N(G)-monomethyl L-arginine abolished the vasodepressor response and reduced the inhibition of SNA induced by I.C.V. injection of 1 micromol L-arginine; such pretreatment increased the arterial pressure, heart rate, and SNA measured 30 min after I.C.V. injection of 10 micromol L-arginine. I.C.V. pretreatment with the angiotensin II type 1 receptor antagonist CV-11974 inhibited the pressor response to 10 micromol L-arginine and the first phase of the pressor response to 10 micromol D-arginine. Intravenous pretreatment with the alpha1-adrenoceptor blocker bunazosin hydrochloride abolished the pressor response to 10 micromol L-arginine and both phases of the pressor response to 10 micromol D-arginine. Brain L-arginine thus appears to exert pressor actions through stimulation of the brain renin-angiotensin system and peripheral SNA. However, these actions may be attenuated by L-arginine-derived nitric oxide.
Nishimura
M
M
Department of Clinical Laboratory and Medicine, Kyoto Prefectural University of Medicine, Kamigyo-ku, Japan.
Takahashi
H
H
Nanbu
A
A
Sakamoto
M
M
Yoshimura
M
M
D000818:Animals; D001120:Arginine / Q000008:administration & dosage / Q000502:physiology*; D001794:Blood Pressure; D001921:Brain / Q000502:physiology*; D002320:Cardiovascular Physiological Phenomena; D006339:Heart Rate; D008297:Male; D009569:Nitric Oxide / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D012084:Renin-Angiotensin System / Q000502:physiology; D013564:Sympathetic Nervous System / Q000502:physiology
D009569:Nitric Oxide; D001120:Arginine