ANOXIA REDUCES DEPOLARIZATION-INDUCED CALCIUM-UPTAKE IN THE RAT HIPPOCAMPAL SLICE

Veratridine-induced depolarization caused a large increase in Ca uptak e in the rat hippocampal slice (30.2 vs. 9.0 nM/mg dry weight). This u ptake was reduced to 18.4 nM/mg when veratridine was combined with ano xia. When compared with veratridine exposure alone, the combination of anoxia and veratridine increased intracellular Na (460 vs. 380 mu M/g ), decreased intracellular K (30 vs. 40 mu M/g) and decreased ATP leve ls (0.1 vs. 0.8 nM/mg). The changes in Na, K, and ATP should enhance n et Ca uptake, yet Ca uptake was reduced. This suggests an effect of an oxia to block Ca channels. In summary anoxia attenuates depolarization -induced Ca uptake. This may represent a mechanism by which neurons ar e partially protected against anoxic damage which could be more severe if depolarization-induced Ca uptake was not limited.