Effect of ethanol on calcium-uptake and phospholipid turnover by stimulation of adrenoceptors and muscarinic receptors in mouse brain and heart synaptosomes

The effect of ethanol treatment on mouse brain and heart synaptosomal 45Ca uptake and the incorporation of 3H]inositol and 14C]choline into phosphatidylinositol (PI) and phosphatidylcholine (PC) were investigated. Ethanol in drinking water (15%) was given to mice for 3 weeks. The consumption of ethanol increased gradually during treatment but food intake was almost the same as control. The body weight of ethanol-treated mice was slightly less than that of control. The synaptosomal lipid peroxidation level of ethanol-treated mice was almost the same as control in the brain and heart. On the other hand, the synaptosomal glutathione level of ethanol-treated mice was higher than control in both brain and heart. The 45Ca uptake of brain and heart from ethanol-treated mice was 87% and 216% of control mice, respectively. Not only ethanol but also norepinephrine (NE), carbachol (Carb), or isoproterenol (IsoPro) added in vitro increased 45Ca uptake in all cases. The incorporation of 3H]inositol into PI in the brain and heart synaptosomes of ethanol-treated mice was 150% and 113% of control, respectively. The incorporation of 14C]choline into PC in the brain and heart of ethanol-treated mice was 104% and 125% of control, respectively. In vitro addition of ethanol, NE, Carb or IsoPro to brain synaptosomes increased the incorporation of 3H]inositol and 14C]choline into PI and PC, respectively, in both control and ethanol-treated mice. In the case of heart synaptosomes, NE and Carb increased the incorporation of 3H]inositol and 14C]choline into phospholipids in control mice but not ethanol-treated mice. However, IsoPro increased the incorporation by both control and ethanol-treated heart synaptosomes. These results suggest that alpha-adrenoceptors and the cholinergic system of the heart play important roles in modulating the toxic effects of ethanol.