Effects of Loperamide on the Motility of the Isolated Intestine in Guinea Pigs, Rats and Dogs.

Effects of Loperamide on the motility of the isolated intestine in guinea-pigs, puppies and rats were examined. The spontaneous contractions of the small intestine and colon in puppies were inhibited at relatively high concentration of the agent (10(-5) g/ml). The peristaltic reflex in the guinea-pig ileum was slightly inhibited at concentrations of 10(-8) to 10(-7) g/ml, and was completely abolished at 10(-6) g/ml. The agent (2X10(-7) g/ml) inhibited the longitudinal contraction of the guinea-pig ileum elicited by transmural electric stimulation. The agent (10(-5) g/ml) inhibited the acetylcholine-induced contraction of the colon and small intestine in puppies, and induced the hyperpolarization of the membrane potential and the abolition of spike potentials of the intestinal muscle in rats.