Abstract
The effects of the toxin extracted from various tissues of wild and cultured puffer fish were investigated in voltage-dependent sodium current (INa) of single rat CA1 neurons, and compared the results to that of tetrodotoxin (TTX). Toxin extracts from wild puffer fish inhibited INa in a dilution-dependent manner, and the toxin extracts from liver or ovary produced 300-500 times greater inhibition than that from the muscle. The inhibition was stronger in the order of liver = ovary >>> eyeball = kidney = intestine > muscle > gills.The toxin extracted from puffer fish cultured in netcages or in tanks set up on land, in an attempt to isolate them from the food chain was also examined. The toxin extracts from these cultured puffer fish also suppressed INa, but the inhibition was much weaker, and the effects of toxin extracts were almost the same in all tissues examined including liver, ovary and muscle etc. We calculated the maximum edible amount for each tissue assuming that lethal dose of TTX is 1-10 μg / kg, and we found that liver or ovary were edible in the case of cultured puffer fish. [J Physiol Sci. 2008;58 Suppl:S130]
