Anoxic changes in dentate granule cells.

In most of the granule cells recorded, by current clamp and single-electrode voltage-clamp (SEVC), only small depolarizations (or inward currents) and minor conductance increases were observed during brief periods of anoxia (2-3 min). Thus, unlike pyramidal cells, granule cell bodies show little sign of K channel activation by anoxia. Post-anoxic hyperpolarizations were also minimal. Moreover, diazoxide (an activator of ATP-sensitive K conductance (GK(ATP]) had no consistent hyperpolarizing action. The depressant effect of diazoxide on anoxic glutamate release from mossy fibres is therefore likely to be mediated by GK(ATP) channels situated on granule cell axons or terminals rather than on the cell bodies.