Acute glutamate toxicity and its potentiation by serum albumin are determined by the Ca2+ concentration

Two different processes, mediated by the N-methyl-D-aspartate receptor, appear to cause acute cell death in cultured cerebellar granule cells. A Ca(2+)-independent process takes place at zero and very low concentration of the added cation. Under these conditions, the known destabilization of excitable membranes at low extracellular Ca2+ probably plays a major role. A Ca(2+)-dependent process becomes dominant as its concentration is increased above 1.0 mM. The remarkable potentiation of glutamate toxicity by serum albumin is a calcium-dependent reaction.