Enhanced stimulatory effect of High Density Lipoproteins (HDL) and other agonists on vascular prostacyclin production in rats fed alcohol-containing diets

Abstract

Chronic administration of liquid diets containing 36% of energy as ethanol to rats increased the serum level of high density lipoproteins (HDL) by 40% and potentiated 2 to 3-fold the stimulatory effect of these lipoporteins on the production of prostacyclin by aortic rings, as compared to pair-fed controls given isocaloric carbohydrate instead of ethanol. Cross-incubations between aortic rings and HDL from either alcohol-fed or pair-fed control rats revealed two factors operating in opposite directions. On the one hand, the predominant mechanism for the potentiation was increased reactivity of the vessel to these lipoproteins. This increased reactivity was also apparent with other agonists of prostacyclin formation. On the other hand, for equal amounts of either cholesterol or protein, the HDL from alcohol-fed rats were less stimulatory than those from controls. This was associated with a smaller content of arachidonate in the HDL of alcohol-fed rats. These ethanol effects on prostacyclin, a potent vasodilator and platelet antiaggregator, may contribute to the decreased incidence of ischemic heart disease observed in moderate alcohol drinkers.