Alcohol induces relaxation of rat thoracic aorta and mesenteric arterial bed

Aims: The aim of this study was to investigate the effect of alcohol on rat artery and its underlying mechanism. Methods: The tension of isolated Sprague-Dawley rat thoracic aortic rings and the pressure of rat mesenteric arterial beds perfused with different concentrations of alcohol (0.1-7.0 parts per thousand) were measured. Results: At resting tensions, alcohol caused a concentration-dependent relaxation on endothelium-denuded aortic rings precontracted with KCl (6x10(-2) mol/L) or phenylephrine (PE, 10(-6) mol/L), and this effect was most evident on rings at a resting tension of 3 g. Alcohol induced much less vasodilation on endothelium-intact rings. Alcohol inhibited the CaCl(2)-induced contraction of endothelium-denuded aortic rings precontracted with KCl or PE. Incubation of rings with dantrolene (5x10(-5) mol/L), a ryanodine receptor blocker, or 2-aminoethyl diphenylborinate (7.5x10(-5) mol/L), an IP(3) receptor blocker, attenuated the vasodilating effect of alcohol on rings precontracted with PE. Alcohol also concentration-dependently relaxed rat mesenteric arterial beds precontracted with KCl (6x10(-2) mol/L) or PE (10(-5) mol/L), which was more potent on endothelium-denuded than on endothelium-intact beds. Conclusions: Alcohol has a vasodilating effect on rat artery depending on the resting tension. Both extracellular and intracellular Ca(2+) mobilization of vascular smooth muscle cells are involved in the vascular effect of alcohol.