Relationship between resting cytosolic Ca and responses induced byN-methyl-d-aspartate in hippocampal neurons

Cytosolic calcium concentrations (Ca²⁺]_i) in cultured hippocampal neurons from rat embryos were measured using fura-2. Neurons with higher resting Ca²⁺]_i showed greater Ca²⁺]_i responses toN-methyl-d-aspartate (NMDA) and K⁺ depolarization. There was a strong relationship between resting Ca²⁺]_i and the maximal changes in Ca²⁺]_i (ΔCa²⁺]_i), which fit the our proposed equation to describe this relationship.