Disopyramide and neuromuscular transmission.

The effect of disopyramide on neuromuscular transmission has been studied using the rat isolated phrenic nerve-diaphragm preparation. The response of the muscle to indirect nerve stimulation was decreased in the presence of disopyramide 5.6 x 10(-6) mol litre-1 (P less than 0.05), total blockade occurring at 5.6 x 10(-4) mol litre-1. Marked augmentation of the response to direct muscle stimulation was recorded in the presence of disopyramide 1.8 x 10(-4)-5.6 x 10(-4) mol litre-1. Disopyramide 5.6 x 10(-6) mol litre-1 caused a leftward shift of the log concentration response for tubocurarine and decreased the antagonist effect of neostigmine.