Sodium-dependent calcium efflux from single Aplysia neurons

45Ca2+ efflux from single Aplysia somata was measured. Replacement of external Na with Tris caused a reduction in the efflux following a transient increase. CCMP, a metabolic poison, caused a reversible increase in the efflux. The results suggest that Na+/Ca2+ exchange and mitochondrial uptake can act to regulate Ca2+ in Aplysia neurons.