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

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 fort-nation 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 Ca2+ chelators, i.e. ethylglycol-bisbeta-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. Veraparnil, 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'. (C) 2003 Elsevier Ireland Ltd. All rights reserved.