CALCIUM INDICATORS AND EXCITOTOXICITY IN CULTURED CORTICAL-NEURONS

Membrane-permeating, fluorescent Ca2+ indicators have been used to inv estigate the role of increased intracelluLar Ca2+ (Ca2+i) levels in ex citotoxic neuronal injury, but their ability to chelate Ca2+i and thei r own toxic effects in some cells could obscure this relationship. N-M ethyl-D-aspartate (NMDA)-stimulated Ca2+i responses and toxicity were measured in neuron-enriched rat cerebrocortical cultures loaded with e ither fluo-3 or fura-2. Ca2+ responses signaled by both indicators wer e similar in magnitude, and neither indicator reduced NMDA toxicity, m easured by lactate dehydrogenase (LDH) release. Fluo-3 and fura-2 appe ar to be suitable for comparative studies of NMDA-induced Ca2+i respon ses and excitotoxicity.