Tetraethylammonium-induced contractions of frog's skeletal muscle. I. General considerations.

Abstract

The mechanism for the production of the 'twitching' response induced by tetraethylammonium (TEA) of the frog's sartorius muscle was investigated. A linear relation was found between the log TEA concentration and the log of the latent period for the onset of the muscle response. The minimum latent period was 5 to 10 sec. Previously it was suggested that TEA caused the release of acetylcholine from intramuscular nerve endings to produce this response (13). The findings that blocking neuromuscular transmission by d-tubocurarine, by reduced extracellular calcium concentrations, or by repetitive indirect stimulation in the presence of hemicholinium also prevented the TEA-induced muscle 'twitching' response support the above suggestion. Exposing the preparation to procaine concentrations too low to block neuromuscular transmission blocked the TEA-induced response, indicating that this response was due to an effect of TEA on the unmyelinated nerve endings.