Nitric oxide inhibits the bradykinin B2 receptor-mediated adrenomedullary catecholamine release but has no effect on adrenal blood flow response in vivo.
The role of nitric oxide (NO) in bradykinin (BK)-induced adrenal catecholamine secretion still remains obscure. The present study was to investigate whether an inhibition of NO synthase with N(omega)-nitro-L-arginine methyl ester (L-NAME) would modulate BK-induced adrenal catecholamine secretion (ACS) and adrenal vasodilating response (AVR) in anesthetized dogs. Plasma catecholamine concentrations were determined with an HPLC coupled with an electrochemical detector. All drugs were locally administered to the left adrenal gland via intra-arterial infusion. BK dose-dependently increased both ACS and AVR. Hoe-140, a selective B(2) antagonist, significantly blocked the BK-induced increases in both ACS and AVR. In the presence of L-NAME, the BK-induced ACS was significantly enhanced, while the simultaneous AVR remained unaffected. These results suggest that the both BK-induced ACS and AVR are primarily mediated by B(2) receptors in the canine adrenal gland. Our results also suggest that the enhanced ACS in response to BK in the presence of L-NAME may have resulted from a specific inhibition of NO formation in the adrenal gland. It is concluded that the BK-induced NO may play an inhibitory role in the B(2)-receptor-mediated mechanisms regulating ACS, while it may not be implicated in the B(2)-receptor-mediated AVR under in vivo conditions.
Bouallegue
Ali
A
The Autonomic Nervous System Research Group, Faculty of Pharmacy, University of Montreal, Quebec, Canada.
Yamaguchi
Nobuharu
N
D000313:Adrenal Medulla / Q000098:blood supply / Q000378:metabolism*; D000818:Animals; D001920:Bradykinin / Q000494:pharmacology; D002395:Catecholamines / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D004285:Dogs; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D043782:Receptor, Bradykinin B2 / Q000502:physiology*; D015203:Reproducibility of Results
D002395:Catecholamines; D004791:Enzyme Inhibitors; D043782:Receptor, Bradykinin B2; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D001920:Bradykinin; D019331:NG-Nitroarginine Methyl Ester