Delayed rectification was elicited in frog's skeletal muscles bathed in choline-Ringer's solution, in normal Ringer's solution with tetrodotoxin, in 40 mM Na(2)SO(4) solution with tetrodotoxin, and even in 40 mM K(2)SO(4) solution when the membrane had been previously hyperpolarized. However, after a sustained depolarization current-voltage relations in 40 mM K(2)SO(4) and in 40 mM Na(2)SO(4) s...

Forty-nine bacterial strains were isolated from deep-sea sediments. Among them, 22 strains were shown by the tissue culture assay method to produce sodium channel blockers. For some strains, high-performance liquid chromatography analysis confirmed that the blocker was tetrodotoxin. Tetrodotoxin-producing bacteria seem to be widespread in marine sediment.