The effects of ethanol on the responses of the vascular musculature to norepinephrine

Abstract Intravenous infusion of ethanol (EtOH) (up to 0.1 ml kg−1 min−1) does not modify the blood pressure in conscious rabbits. In this range of doses, EtOH brings about an increase of the pressure responses induced by norepinephrine (NE) with respect to values obtained in the absence of EtOH. Similar experiments have been performed on the isolated rat tail artery: EtOH perfusion does not modify the basal tone of the preparation up to 2% concentration, while the contractile response to NE administration is potentiated. The supersensitivity of the arteries to NE induced by EtOH, is a function of EtOH concentration and can be represented by a bell-shaped curve reaching the maximal value at 1% EtOH, whereby concentrations larger than 2% induce an inhibition of NE activity. The present experiments suggest that the potentiation of the contractile effects of NE induced by EtOH might be related to an enhancement of the rate of calcium transport due to the increase in cell membrane plasticity induced by EtOH.