Ethanol hyperpolarizes mitochondrial membrane potential and increases mitochondrial fraction in cultured mouse myocardial cells

Cultured mouse heart-derived myocardial and non-muscle cells were exposed to ethanol, stained with cell-permeant fluorescent vital probes, JC-1 (5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolyl-carbocyanine iodide) and oxidation-sensitive dihydrorhodamine 123, and analyzed by flow cytometry to elucidate ethanol-induced time-wise alterations in the mitochondrial membrane potential (Delta Psi m) and the production of reactive oxygen species (ROS). Ethanol (50 and 200 mM) not only hyperpolarized Delta Psi m of both types of cells but also dose-dependently increased ROS production at 24 h, although a 200-mM dose reduced the production until 3 h. These cell pathophysiological reactions suggest the depression of mitochondrial ATPase and mitochondrial respiratory chain. However, differences between these cells appeared after a 24-h exposure to 200 mM ethanol: the increase in ROS production was approximately twice as large for myocardial cells as for non-muscle cells; and the side-scatter parameter of light scattering significantly increased for myocardial cells, but not for non-muscle cells. All these myocyte-specific alterations indicate an increase in the mitochondrial fraction in a cell. This reaction might be a countermeasure against ethanol-induced dysfunction of mitochondrial respiration that is needed to meet the energy requirements of spontaneous myocardial contractions.