Immersion of motile specimens of Ascaris lumbricoides in piperazine solutions gradually results in paralysis of the worms. When the worms are split the muscle of the body wall contracts in response to acetylcholine. This response is rapidly blocked by dilute solutions of piperazine. Electrical stimulation of the muscle of the body wall also causes contraction. This contraction is not blocked by perfusion of this preparation with piperazine. This evidence indicates that piperazine produces paralysis of Ascaris by blocking the neuromuscular junction. This observation can account for the therapeutic effectiveness of piperazine against Ascaris. Ascaris muscle responds to several pharmacologically active compounds in a manner resembling vertebrate skeletal muscle.
Reported in part at the annual meeting of the American Society of Tropical Medicine and Hygiene, New Orleans, La., 1956.