Influence of chronic alcohol ingestion on acetaldehyde-induced depression of rat cardiac contractile function.

Long-standing ethanol consumption acts as a chronic cardiac stress and often leads to alcoholic cardiomyopathy. We have recently shown that the acute ethanol-induced depression in myocardial contraction was substantiated by chronic ethanol ingestion. Acetaldehyde (ACA), the main ethanol metabolite, has been considered to play a role in ethanol-induced cardiac dysfunction. To evaluate the ACA-induced cardiac contractile response following chronic ethanol ingestion, mechanical properties were examined using left ventricular papillary muscles and myocytes from rats fed with control or ethanol-enriched diet. Muscles and myocytes were electrically stimulated at 0.5 Hz and contractile properties analysed included peak tension development (PTD) and peak shortening (PS). Intracellular Ca(2+) transients were measured as fura-2 fluorescence intensity changes (DeltaFFI). Papillary muscles from ethanol-consuming animals exhibited reduced baseline PTD and attenuated responsiveness to increase of extracellular Ca(2+). Acute ACA (0.3-10 mM) addition elicited a dose-dependent depression of PTD. However, the inhibition magnitude was significantly reduced in ethanol-treated rats. Myocytes from both control and ethanol-treated rats exhibited comparable ACA-induced depression in both PS and DeltaFFI. Collectively, these data suggest that the ACA-induced depression of myocardial contraction is reduced at the multicellular level, but unchanged at the single cell level, following chronic ethanol ingestion.