Effects of Neuromuscular Blocking Agents and Acetylcholinesterase Inhibitors on the Response of Pectoral Fin Muscle of the Sculpin (Enophrys bison) to Indirect Stimulation

Abstract The neuromuscular junction of the buffalo sculpin (Enophrys bison) was characterized in situ by examining the effects of various neuromuscular blocking agents and acetylcholinesterase inhibitors (ACHE-I) on pectoral muscle response to indirect stimulation. The injection of either d-tubocurarine (350 μg/kg) or α-bungarotoxin (α-Butx) (1 mg/kg) resulted in a flaccid paralysis. The depolarizing agents, succinylcholine (11 μg/kg) and decamethonium (42 μg/kg), produced a spontaneous contraction. The administration of the ACHE-I, diisopropyl fluorophosphate (DFP), and eserine resulted in responses which were contrary to those expected based on similar experiments using mammalian skeletal muscle. Twitch potentiation did not occur and the ability to maintain a tetanic response was not abolished even after the administration of clearly lethal concentrations of ACHE-I.