Cyanide induces Ca(2+)-dependent and -independent release of glutamate from mouse brain slices.

The effect of cyanide-induced histotoxic hypoxia on endogenous glutamate release from mouse cortical, cerebellar and hippocampal slices was studied. Incubation of slices with cyanide over a 30 min period resulted in extracellular accumulation of glutamate which was decreased in the absence of Ca2+ in the incubation media. When glutamate release was continuously monitored by fluorometry, cyanide initiated a rapid release of glutamate. This initial release was found to be independent of extracellular calcium. Depolarizing concentrations of potassium chloride produced a predominantly Ca(2+)-dependent release. It is concluded that cyanide exposure induced a rapid release of endogenous glutamate mediated by both Ca(2+)-dependent and Ca(2+)-independent mechanisms.