Membrane currents elicited by the epileptogenic drug pentylenetetrazole in the native oocyte of Xenopus laevis.

The effects of the epileptogenic agent pentylenetetrazole (PTZ) on membrane currents of native oocytes of Xenopus laevis were studied. PTZ elicits a response that consists of two inward currents. The first one is interpreted to be due to a decrease of potassium permeability since: (1) the input resistance is increased; (2) the equilibrium potential is near that of potassium; (3) the current is decreased during administration of potassium channel blocking agents; and (4) the PTZ response can be mimicked by blocking potassium channels without PTZ application. The second one is interpreted to be due to an increase of chloride permeability since: (1) the input resistance is decreased; (2) the equilibrium potential is near that of chloride; and (3) the response is decreased during administration of chloride blocking agents. These findings correspond to some extent with those made in neurons.