Electromyographic Studies of Effects of Various Drugs on Fibrillation in Denervated Muscle of Rabbit

Abstract

Electromyographic studies were made of effects of various drugs injected intravenously on fibrillation voltage appeared in chronically denervated tibialis anterior muscle of rabbit. The drugs used were succinylcholine, nicotine, vagostigmin, acetylcholine, veratrine, hexamethonium, tofranil, adrenaline, dimethylaminoethanol, GABA and quinidine.
1) Succinylcholine, nicotine and veratrine produced remarkable facilitation for several minutes followed by depression of fibrillation voltage continued for fifteen minutes or over.
Vagostigmin and acetylcholine also had the action like succinylcholine, but its potency was much lower than that of the latter drug.
2) Quinidine, adrenaline, tofranil and also GABA produced depression of fibrillation voltage. Before the depression by these drugs was induced, the facilitation of fibrillation voltage was produced for several minutes by quinidine and also by GABA. Dimethylaminoethanol caused the mild, but long continued facilitation after the temporary depression of fibrillation voltage.
3) Hexamethonium had no significant effect on fibrillation voltage.