Influence of the drugs for membrane excitability modification on the excitation caused by achatin-I

1. The pneumatic pressure ejection of achatin-I (Gly-D-Phe-L-Ala-L-Asp), an endogenous tetrapeptide having a D-phenylalanine residue, produced an inward current (Iin) in an identifiable giant neuron, PON (periodically oscillating neuron), of an African giant snail, Achatina fulica Férussac. The influence of the drugs for membrane excitability modification, applied by perfusion, on the PON excitation caused by achatin-I was examined under voltage clamp. 2. The four channel blocking drugs, tetrodotoxin (TTX), tetraethylammonium chloride (TEA), verapamil and picrotoxin, at 10(-4) M did not affect significantly the PON excitation caused by the peptide. 3. N-beta-phenylpropionyl-L-tyrosine (BPLT), a membrane hyperpolarizant, at 10(-6) M and concanavalin A (Con A), which altered the response to L-glutamate, at 100 micrograms/ml-1 were considered to hardly influence the PON excitation caused by achatin-I.