Involvement of AMPK in Alcohol Dehydrogenase Accentuated Myocardial Dysfunction Following Acute Ethanol Challenge in Mice.

Objectives: Binge alcohol drinking often triggers myocardial contractile dysfunction although the underlying mechanism is not fully clear. This study was designed to examine the impact of cardiac-specific overexpression of alcohol dehydrogenase (ADH) on ethanol-induced change in cardiac contractile function, intracellular Ca2+ homeostasis, insulin and AMPdependent kinase (AMPK) signaling. Methods: ADH transgenic and wild-type FVB mice were acutely challenged with ethanol (3 g/kg/d, i.p.) for 3 days. Oral glucose tolerance test, cardiac AMP/ATP levels, cardiac contractile function, intracellular Ca2+ handling and AMPK signaling (including ACC and LKB1) were examined. Results: Ethanol exposure led to glucose intolerance, elevated plasma insulin, compromised cardiac contractile and intracellular Ca2+ properties, downregulated protein phosphatase PP2A subunit and PPAR-γ, as well as phosphorylation of AMPK, ACC and LKB1, all of which except plasma insulin were overtly accentuated by ADH transgene. Interestingly, myocardium from ethanol-treated FVB mice displayed enhanced expression of PP2Cα and PGC-1α, decreased insulin receptor expression as well as unchanged expression of Glut4, the response of which was unaffected by ADH. Cardiac AMPto- ATP ratio was significantly enhanced by ethanol exposure with a more pronounced increase in ADH mice. In addition, the AMPK inhibitor compound C (10 μM) abrogated acute ethanol exposure-elicited cardiomyocyte mechanical dysfunction. Conclusions: In summary, these data suggest that the ADH transgene exacerbated acute ethanol toxicity-induced myocardial contractile dysfunction, intracellular Ca2+ mishandling and glucose intolerance, indicating a role of ADH in acute ethanol toxicity-induced cardiac dysfunction possibly related to altered cellular fuel AMPK signaling cascade. [ABSTRACT FROM AUTHOR]