Vascular reactivity in alcoholic rat aortas: in vitro interactions between catecholamines and alcohol

To understand the nature of vascular problems of hypertensive and alcoholic subjects, an in vitro interaction between catecholamine and alcohol was investigated in male Sprague-Dawley rats. The descending aortas were isolated from either the control or alcohol treated rats. The aortic strips were cooled rapidly in ice-chilled Krebs-Henseleit (K-H) solution and the aorta was cut into a series of rings of approximately 1 mm width. The rings were fixed under 1 g of resting tension between a force-displacement transducer and anchoring electrodes at 37 degrees C. The rings were equilibrated for an hour with frequent changes of the K-H solution before testing. There was norepinephrine (NE) dose-dependent contraction of the rings, which showed the maximum tension with 1 microM NE. Acetylcholine or carbachol produced slow relaxation. Pretreatment of the rings with 10 microM prazocin prevent the contraction induced by 1 microM NE. Even in the presence of prazocin, 60 mM KCI was able to generate the maximum tension. NE-induced contraction was analyzed in the control K-H solution or in the presence of 1.5, 3.0 and 5.0% of ethanol. Ethanol (1.5%) slowed the rate of rise of the aortic tension without a remarkable compromise of the maximum tension. But, there was a significant reduction in contraction with 3% ethanol. A complete inhibition of contraction was noted with 5% ethanol. However, the effect of ethanol was fully reversible upon washings the aortic rings with K-H solution. Aortic rings prepared from the rats that were fed with alcohol for 30 days were not able to generate the maximum tension with 1 microM NE.(ABSTRACT TRUNCATED AT 250 WORDS)