Stimulus frequency and neuromuscular block.

Muscle twitches of the rat isolated diaphragm and frog sartorius preparations were recorded. It was confirmed that, in the presence of tubocurarine, the degree of neuromuscular block was greater the higher the frequency of stimulation. The results suggest that the quantity of acetylcholine released by each nerve impulse was reduced by increasing the rate of stimulation so that, in a tubocurarine solution, muscle fibres which were only just being fired at a slow rate of stimulation failed to fire at a faster rate.