Abstract

EVORA, Paulo Roberto B. et al. Effect of arginine vasopressin on the canine epicardial coronary artery: experiments on V₁-receptor-mediated production of nitric oxide. Arq. Bras. Cardiol. [online]. 2003, vol.80, n.5, pp.489-494. ISSN 1678-4170.  https://doi.org/10.1590/S0066-782X2003000500002.

OBJECTIVE: To determine whether arginine vasopressin releases endothelium-derived nitric oxide (EDNO) from the epicardial coronary artery. METHODS: We studied segments of canine left circumflex coronary arteries suspended in organ chambers to measure isometric force. The coronary artery segments were contracted with prostaglandin F_2a (2 x 10^-6M) and exposed to a unique, strong arginine vasopressin concentration (10^-6M) or titrated concentrations (10^-9 a 10^-5 M). RESULTS: The unique dose of arginine vasopressin concentration (10^-6M) induced transient, but significant (p<0.05), relaxation in arterial segments with endothelium, and an increase, not significant, in tension in arteries without endothelium. Endothelium-dependent relaxation to arginine vasopressin was inhibited by Ng-monomethyl-L-arginine (L-NMMA, 10^-5M) or N^G-nitro-L-arginine (L-NOARG) (10^-4M), 2 inhibitors of nitric oxide synthesis from L-arginine. Exogenous L-arginine (10^-4M), but not D-arginine (10^-4M), reversed the inhibitory effect of L-NMMA on vasopressin-mediated vasorelaxation. Endothelium dependent relaxation to vasopressin was also reversibly inhibited by the vasopressin V₁-receptor blocker d(CH₂)₅Try(Me) arginine vasopressin (10^-6M) (n=6, P<0.05). CONCLUSION: Vasopressin acts through V₁ endothelial receptors to stimulate nitric oxide release from L-arginine.

Keywords : coronary artery; vasopressin; endothelium; nitric oxide.

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