Differential responses between CA1 pyramidal cells and granule cells to ischemic insult in rat hippocampal slices.

Differential responses between CA1 pyramidal cells (PCs) and granule cells (GCs) to transient ischemic insults (oxygen and glucose deprivation, Hypo center dot G(-)) were studied in rat hippocampal slices using simultaneous recordings of membrane potentials and intracellular Ca2+ concentrations ([Ca2+]i). The average resting membrane potentials before Hypo center dot G(-) were significantly different between PCs (-66.5 +/- 1.5 mV) and GCs (-78.5 +/- 2.0 mV). In PCs, Hypo center dot G(-) produced an initial hyperpolarization and a subsequent rapid and large depolarization. In contrast, in GCs, Hypo center dot G(-) produced a gradual depolarization with an initial slight hyperpolarization. [Ca2+]i increased corresponding to the depolarization. The [Ca2+]i levels during Hypo center dot G(-) and after reoxygenation were significantly higher in the CA1 than in the dentate gyrus. These results suggest that PCs are more susceptible to Hypo center dot G(-) than GCs, as judged by the speed of depolarization and the elevation in [Ca2+]i.