Mobilization of [Ca2+]i in the monkey hippocampal slices during transient hypoxia-hypoglycemia and KCl-induced depolarization was analyzed by microfluorometric imaging and anti-PIP2 immunohistochemistry. Hypoxia-hypoglycemia provoked the largest [Ca2+]i mobilization of CA-1 temperature-dependently whereas [Ca2+]i mobilization by KCl-induced depolarization occurred independent of the temperature in CA-2. Immunohistochemical analysis of the hippocampus after hypoxia-hypoglycemia showed an increased PIP2 staining preferentially in the perikarya of CA-1 neurons. These data suggest that release of Ca2+ from intracellular stores caused by PIP2 breakdown may induce elevated [Ca2+]i.