Alcohol-induced apoptosis of canine cerebral vascular smooth muscle cells: role of extracellular and intracellular calcium ions

Abstract

Exposure of canine cerebral vascular smooth muscle cells (VSMCs) to ethanol (10, 25 and 100 mM) for 1, 3 and 5 days induced apoptosis with its typical characteristics of nuclear shrinkage, condensation, and DNA breakage as well as formation of apoptotic bodies observed by fluorescence staining, terminal deoxyribonucleotidyl transferase-mediated dUTP nick-end labeling and comet assays. Such effects of alcohol on cerebral VSMCs were time- and concentration-dependent. The threshold ethanol concentration for induction of the apoptotic process was found to be 10 mM. Extracellular and intracellular Ca 2+ chelators, i.e. ethylglycol-bisβ-aminoethylether- N, N, N′ N′-tetraacetic acid (EGTA, 5 mM) and 1,2-bis(2-aminophenoxy)-ethane- N, N, N′, N′-tetra-acetic acid AM (BAPTA, 10 −6 M), respectively, ameliorated greatly the number of cerebral VSMCs which underwent apoptosis. Verapamil, however, failed to inhibit apoptosis of cerebral VSMCs. From these new findings, we suggest that alcohol-induced apoptosis may contribute to alcohol-induced brain-vascular damage and stroke. In addition, our findings point to potential caution for humans who imbibe two or more standard drinks per day or who undergo ‘binge drinking’.