End-plate potentials in frog muscle exposed to a synthetic pyrethroid

Abstract Isolated sartorius nerve-muscle preparations from Rana temporaria were irrigated in a chamber. Resting muscle membrane potentials and evoked end-plate potentials were recorded via intracellular microelectrodes. Multiple end-plate potentials appeared after the preparation had been exposed to a suspension, in Ringer's solution, of the toxic synthetic pyrethroid: 5-benzyl-3-furylmethyl (+)- cis -chrysanthemate (NRDC 119). It is thought that this effect was due to repetitive activity arising in the motor nerve fibers. The pyrethroid had no effect on the muscle resting potential nor on the amplitude or time course of the initial evoked end-plate potential.