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, thoracotomized, artificially ventilated dogs by using a radioactive microsphere technique. The control group (n = 5) received saline. The smaller dose of ethanol decreased perfusion in the left ventricular myocardium from 0.737 +/- 0.122 to 0.555 +/- 0.122 ml/g/min (NS), whereas the greater dose 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 evident in subendocardial layers (p < 0.01 both within the groups and between the groups). The greater dose of ethanol increased systemic vascular resistance (p < 0.01 when compared to the control group). The changes in right ventricular myocardium were insignificant. The acute effect of ethanol on coronary blood flow is dose-dependent with small to moderate doses reducing demand for left ventricular flow but with increasing doses evoking not only an increase in demand for flow but also an increase in flow.