Convulsants antagonise inhibition in the olfactory cortex slice.

The effects of some gamma-aminobutyric acid (GABA) antagonists and other "convulsants" have been tested on neurones of the isolated olfactory cortex slice preparation of the guinea-pig using single cell intracellular and gross extracellular recording techniques. Bicuculline, picrotoxin, strychnine, leptazol, bemegride, and also theophylline and d-tubocurarine all increased the duration and amplitude of the excitatory postsynaptic potential, thereby producing a seizure-like discharge. These drugs reduced and shortened the peak conductance increase during the inhibitory postsynaptic potential (i.p.s.p.) in normal solution and after the i.p.s.p. had been prolonged by the presence of a barbiturate. The results suggested that these drugs antagonise synaptic inhibition through a common mechanism, perhaps by reducing the effect of neurally released GABA.