ACTIVITY-DEPENDENT SURVIVAL OF RAT CEREBELLAR GRANULE NEURONS IS NOT ASSOCIATED WITH SUSTAINED ELEVATION OF INTRACELLULAR CA2+

Ca2+ plays a pivotal role for the activity-dependent survival of neuro ns. In primary culture of cerebellar granule neurons, we found that th ere is no significant difference in intracellular Ca2+ level in the su rvival-promoting condition (cultures in the presence of 25 mM KCl) and that in the apoptosis inducing condition (cultures in the presence of 5 mM KCl). This was not due to the inactivation of voltage-dependent L-type Ca2+ channels in the survival-promoting condition, but due to t he enhanced rate of the influx and the efflux of Ca2+ in the survival promoting condition compared to that in the apoptosis-inducing conditi on. These results suggest that the activity-dependent survival of the granule neurons is nor associated with sustained rise of intracellular Ca2+ but associated with the enhanced turnover rate of Ca2+. (C) 1997 Elsevier Science Ireland Ltd.