Continuous osmotic minipump infusion of alcohol into brain decreases brain [Mg2+] and brain bioenergetics and enhances susceptibility to hemorrhagic stroke:: An in vivo 31P-NMR study

P-31-NMR spectroscopic studies were performed in vivo on brains of rats chronically infused for 7 and 14 days with 30% ethanol (in the third cerebral ventricle). Peripheral blood alcohol concentration (BAC) rose to between 16.5-30.5 mg/dl. Brain intracellular free Mg2+ ([Mg2+](i)) fell 33-39%, brain mitochondrial cytosolic phosphorylation potential (CPP) fell 31-48%, and brain phosphocreatine (PCr) fell approximately 15%; however, neither brain intracellular free hydrogen ion concentration (pHi) nor brain intracellular inorganic phosphate (Pi) were affected significantly by the chronic release of ethanol from the brain implants. Correlations were found between [Mg2+](i) and [PCr] and between [Mg2+](i) and CPP. Although brain free [MgADP] was not affected, [MgATP] fell by almost 20% accompained by a 35-40% rise in free [ADP]. Interestingly, 14-day surgical implantation of 0.;9% sterile saline into the third cerebral ventricle was associated with a 20% fall in brain [Mg2+](i) and a 35% fall in CPP; however, PCr, ATP, or pHi was not significantly altered. Systemic administration of 4 g/kg ethanol into the 7- and 14-day chronic ethanol animals resulted in a 9- and 12-fold increase in hemorrhagic stroke mortality compared to naive, control rats. Eating habits, grooming, gait and arterial blood pressure were not affected by the chronic brain implantation of ethanol. These data lend support to the notion, primarily based on epidemiologic evidence, that chronic exposure to alcohol can pose a high risk for hemorrhagic stroke. Our alcohol pump-implanted rats also might provide a new model of slow, moderate alcohol intoxication. (C) 1998 Elsevier Science Inc.