EFFECTS OF PENTYLENETETRAZOL ON GABA RECEPTORS EXPRESSED IN OOCYTES OF XENOPUS-LAEVIS - EXTRACELLULAR AND INTRACELLULAR SITES OF ACTION

The convulsive agent pentylenetetrazol (PTZ) antagonized gamma-aminobu tyric acid (GABA)-induced membrane currents on RNA-injected Xenopus oo cytes with both extra- and intracellular applications. With extracellu lar administration PTZ enters the cell within a few minutes and reache s concentrations in the millimolar range. The permeability of the plas ma membrane makes it possible for systemically applied PTZ to elicit i ts effect on the GABA-induced currents via extra- as well as intracell ular sites of action.