No abstract

The rat phrenic nerve hemidiaphragm and chick biventer-cervicis preparations were used to investigate the effect of a crude aqueous extract of Ipomoea fistulosa. Electrically-induced skeletal muscle twitches of the hemidiaphragm were blocked by the extract and by tubocurarine. The anticholinesterase, physostigmine, intensified the blockade by the extract. The extract produced contracture of the chick biventer-cervicis preparation. It is suggested that the extract possesses neuromuscular blocking activity of a depolarizing nature.