[Effect of alcohol on vascular function].

Vascular function is regulated by a balance of vasoconstriction and vasorelaxation. Disorder in this balance due to alcohol consumption causes various clinical conditions. In this review, we discuss the effects of acute and chronic ethanol consumption on vascular responses, including vasoconstriction, endothelium-dependent vasorelaxation, and nerve-mediated vasorelaxation. Acute ethanol administration induces vasoconstriction in ethanol-naive animals in vitro. Furthermore, ethanol can both potentiate and suppress agonist-induced Ca(2+)-dependent vasoconstriction. Moreover, ethanol augments Ca(2+)-independent vasoconstriction by increasing Ca2+ sensitivity. Endothelium-dependent relaxation is mediated by the nitric oxide (NO) pathway and the endothelium-derived hyperpolarizing factor (EDHF) pathway. Acute ethanol treatment inhibits both NO- and EDHF-mediated relaxation. Furthermore, acute ethanol ingestion can also potentiate and suppress calcitonin gene-related peptide (CGRP)-induced nerve-mediated relaxation. These opposing effects may be due to differences in species or vascular beds. Thus, acute ethanol treatment decreases vasorelaxation, thereby shifting the contraction-relaxation balance towards contraction. Combined, these effects are one mechanism by which acute heavy alcohol consumption causes circulatory disturbances such as vasospasms or ischemic heart disease. In contrast, chronic low-dose ethanol has no effect on vasoconstriction, whereas chronic high-dose ethanol increases vasoconstriction. Additionally, chronic ethanol intake has diminished, unchanged, and even increased effects on nerve-mediated relaxation; therefore, conclusions on these effects are not possible at present. Interestingly, chronic low-dose ethanol administration enhanced endothelium-dependent relaxation; however, higher doses inhibited these responses. Therefore, regular or light-to-moderate alcohol intake increases vasorelaxation and may suppress elevated blood pressure, whereas chronic heavy alcohol consumption may raise blood pressure, causing various clinical conditions.