PENTYLENETETRAZOL-INDUCED INTRACELLULAR POTENTIAL CHANGES OF THE NEURON OF THE JAPANESE LAND SNAIL EUHADRA PELIOMPHALA

The effect of Pentylenetetrazol (PTZ, Metrazol) upon the identified neurons of Japanese land snail was studied. 1) In the pleuro-parieto-visceral ganglion of Japanese land snail, Euhadra peliomphala, three types of cells can be differentiated morphologically and functionally as those; depolarized by acetylcholine (D-cell), hyperpolarized by acetylcholine (H-cell) and indifferent to acetylcholine (I-cell). 2) PTZ produces a phasic depolarization followed by a sustained depolarization in the D- and H-cells. 3) PTZ has no specific effect upon the I-cell. 4) By application of d-tubocurarine, atropine and hexamethonium, the typical phasic activity evoked by PTZ is not affected in either the D- or H-cells, suggesting that the effect of PTZ is not of synaptic origin but of endogeneous origin. 5) Neither cholinergic nor noncholinergic inhibitory input to the Dand H-cells are affected even at the peak of PTZ activity.