Effects of argininosuccinic acid on nitric oxide-mediated relaxations in rat aorta and anococcygeus muscle.
1. Argininosuccinic acid (ASA), a naturally occurring NG derivative of arginine, and the nitric oxide synthase (NOS) inhibitor NG-nitro-L-arginine methyl ester (L-NAME) were compared for their ability to reduce responses to nitric oxide (NO) derived from endothelial cells (aorta) and nitrergic nerves (anococcygeus muscle). 2. In isolated rings of rat aorta, endothelium-dependent relaxation responses to acetylcholine were abolished by L-NAME (0.1 mmol/L) and were reduced by ASA (0.1 and 0.3 mmol/L). Relaxations induced by sodium nitroprusside (SNP) were not affected by L-NAME but were reduced by ASA. 3. In rat isolated anococcygeus muscles, relaxations elicited by nitrergic nerve stimulation at 1 Hz were abolished by L-NAME (0.1 mmol/L) but were only slightly reduced by ASA (1 mmol/L). The effect of ASA was not sustained. L-Arginine (1 mmol/L) prevented the effect of L-NAME but not that of ASA. Neither ASA or L-NAME inhibited SNP-induced relaxation in the anococcygeus muscle. 4. The results suggest that ASA inhibits NOS but this does not totally account for its effects in reducing NO-mediated relaxations produced by the endothelium-dependent vasodilator acetylcholine in rat aortic rings and stimulation of nitrergic nerves in the rat anococcygeus muscle.
Rand
M J
MJ
Department of Pharmacology, University of Melbourne, Parkville, Victoria, Australia.
Li
C G
CG
D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects* / Q000502:physiology; D001120:Arginine / Q000031:analogs & derivatives / Q000037:antagonists & inhibitors / Q000494:pharmacology; D001125:Argininosuccinic Acid / Q000494:pharmacology*; D004558:Electric Stimulation; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009126:Muscle Relaxation / Q000187:drug effects* / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000502:physiology; D009132:Muscles / Q000187:drug effects* / Q000294:innervation; D019331:NG-Nitroarginine Methyl Ester; D009569:Nitric Oxide / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology
D001125:Argininosuccinic Acid; D009569:Nitric Oxide; D001120:Arginine; D019331:NG-Nitroarginine Methyl Ester