Inhibition of Na currents by the toxin extracts from puffer fishes captured in the sea coast of Japan.

The inhibitory effects of toxin extracted from muscle or liver of five different puffer fishes (hereafter referred as puffer(s)) captured on the Japanese sea coast were examined on voltage-dependent sodium current (I(Na)) recorded from dissociated single rat hippocampal CA1 neurons. The inhibitory effects estimated from IC(50) values of toxin extracts on I(Na) were in the order of Takifugu vermicularis > Lagocephalus wheeleri > Canthigaster rivulata > Takifugu rubripes > Arothron reticularis from muscle and T. vermicularis > T.

Quantitative analysis of toxin extracts from various tissues of wild and cultured puffer fish by an electrophysiological method.

We observed the effects of the toxin extracted from various tissues of wild and cultured puffer fish on voltage-dependent sodium current (I(Na)) using single rat CA1 neurons, and compared the results with that of tetrodotoxin (TTX). Toxin extracts from wild puffer fish inhibited I(Na) in a dilution-dependent manner, and toxin extracts from liver or ovary produced 300 times greater inhibition than that from muscle, and corresponded to about 65 microg TTX/g tissue. We also used puffer fish cultured in net cages or in tanks set up on land, in an attempt to isolate them from the food chain.