Effects of pentobarbital, ethanol and morphine on subcellular localization of calcium and magnesium in brain

The effects of acute and chronic administration of pentobarbital and ethanol and of acute administration of moprphine on the subcellular localization of calcium and magnesium were determined in brain. Acute administration of pentobarbital to mice significantly decreased the calcium content of synaptic plasma membranes, (SPM-1), while increasing the calcium content of extrasynaptosomal mitochondria. After chronic administration of pentobarbital, the calcium content of SPM-1 remained depressed but no other alterations were detected. Neither acute nor chronic treatment with pentobarbital altered the subcellular localization of magnesium in brain. Acute injection of morphine decreased the synaptosomal calcium concentration in rat brain. In contrast to these effects of pentobarbital and morphine, acute administration of ethanol to mice or rats failed to alter the calcium content of any subcellular fraction studied. In addition, acute treatment with either ethanol or morphine failed to alter the calcium or magnesium content of tissue samples from rat cortex. Chronic ethanol treatment did not alter the concentration of calcium in any subcellular fraction, but did decrease the concentration of magnesium in both myelin and serum. This finding is discussed in terms of the role of magnesium deficiency in chronic alcoholism. Taken together, these results indicate that pentobarbital, ethanol and morphine each produce distinct alterations in the subcellular localization of calcium and magnesium in brain.