THE ACUTE DOSE-DEPENDENT EFFECTS OF ETHANOL ON CANINE MYOCARDIAL PERFUSION

The acute effects of ethanol (1.0 g/kg and 1.5 g/kg, n = 4 and n = 5, yielding blood concentrations of 1.3 +/- 0.2 mg/ml and 2.4 +/- 0.3 mg/ ml) on myocardial perfusion were studied in anesthetized, thoracotomiz ed, artificially ventilated dogs by using a radioactive microsphere te chnique. The control group (n = 5) received saline. The smaller dose o f ethanol decreased perfusion in the left ventricular myocardium from 0.737 +/- 0.122 to 0.555 to 0.122 ml/g/min (NS), whereas the greater d ose nonsignificantly increased it, from 0.744 +/- 0.115 to 0.819 +/- 0 .119 ml/g/min (p < 0.01 between the groups). These changes were most e vident in subendocardial layers (p < 0.01 both within the groups and b etween the groups). The greater dose of ethanol increased systemic vas cular resistance (p < 0.01 when compared to the control group). The ch anges in right ventricular myocardium were insignificant. The acute ef fect of ethanol on coronary blood flow is dose-dependent with small to moderate doses reducing demand for left ventricular now but with incr easing doses evoking not only an increase in demand for flow but also an increase in flow.