Effects of chronic ethanol consumption on alpha-adrenergic-induced contractions and endothelium-dependent relaxations in rat thoracic aorta

The effects of chronic oral administration of ethanol (7.2% daily during 24 weeks) on the contractions induced by phenylephrine (Phe) and the endothel ium-dependent relaxation responses to acetylcholine (ACh) were studied in r at thoracic aorta. Ethanol pretreatment significantly attenuated the contra ctile responses to Phe, resulting in parallel shift of the concentration-re sponse curve to the right. EC50 values of Phe were 64.6 +/- 11.2 and 95.5 /- 8.5 nmol l(-1) in control and ethanol-fed rats, respectively. On the oth er hand, either calcium-induced contractions or relaxation responses to ACh and sodium nitroprusside were similar in the vessels of the control and et hanol-treated rats. These results suggest that chronic ethanol ingestion si gnificantly attenuates the alpha(1)-adrenergic-induced contractions but doe s not affect the relaxation responses mediated by nitric oxide in rat aorti c rings. (C) 2000 Academic Press.