The effect of lysolecithin on contractile force of isolated gastric smooth muscle.

Mechanical activity of smooth muscle preparations was recorded in circular strips of antrum, corpus, and fundus from guinea-pig stomach. Whereas acetylcholine stimulated both rhythmic and tonic (shift of the base line) activity of the tested muscles, lysolecithin induced tonic contractions, but had no influence on the rhythmic activity. Lysolecithin was ineffective in the absence of external calcium. The tonic activations of corpus and fundus preparations induced by lysolecithin were suppressed by sodium nitroprusside. D 600 (methoxy-verapamil) did not counteract the lysolecithin effect.