The leading role of membrane Ca(2+)-ATPase in recovery of Ca(2+) homeostasis after glutamate shock

Combined blockade of Na⁺/Ca²⁺ exchange, Ca²⁺ uptake by mitochondria and endoplasmic reticulum usually does not prevent recovery of the basal level of intracellular Ca²⁺ after 1-min action of glutamate (100 M) or K⁺ (50 mM). However, replacement of Ca²⁺ with Ba²⁺, which cannot be transported by Ca²⁺-ATPase, considerably delayed the decrease in intracellular Ba²⁺ after its rise caused by glutamate or potassium application in all examined cells, which attest to an important role of Ca²⁺-ATPase in Ca²⁺ extrusion after the action of glutamate or K⁺.