Acute effects of acetaldehyde and ethanol on rat heart mitochondria

The effects of acute exposure of rat heart mitochondria to ethanol (87, 65, and 45 mM) and acetaldehyde (3, 1, and 0.3 mM) were studied using both glutamate and pyruvate/malate substrates. Mitochondria assayed with pyruvate/malate substrate showed no apparent effects of acute exposure to or 30 min preincubation with ethanol at the three concentrations tested. With glutamate substrate, acute ethanol at 87 and 65 mM produced significant decreases in respiratory control ratio (RCR). With 65 and 45 mM acute ethanol, mitochondrial oxygen consumption (QO2) was significantly decreased. Acute acetaldehyde significantly decreased RCR and QO2 of mitochondria tested with both substrates. The depressive effect was more pronounced with pyruvate/malate substrate than with glutamate substrate. With pyruvate/malate substrate, the ADP/O ratio was also decreased with 3 and 1 mM acetaldehyde. Preincubation with acetaldehyde had no effect on mitochondrial function except for significantly decreased RCR after preincubation with 3 mM acetaldehyde followed by assay with glutamate substrate. The data indicate a depressant effect of acetaldehyde and ethanol on cardiac mitochondria that may contribute to abnormal cardiac biochemistry and function characteristic of alcoholic cardiomyopathy.