AN ATYPICAL ACTION OF ACETYLCHOLINE ON THE STRIPED MUSCLE OF THE GUINEA-PIG SOPHAGUS

¹ Department of Veterinary Pharmacology, Royal (Dick) School of Veterinary Studies, Edinburgh

Acetylcholine produced a longitudinal contraction of the separated externa of the guinea-pig sophagus, which was blocked by cocaine or tubocurarine and was partially antagonized by hexamethonium or hyoscine. Acetyl--methylcholine was almost without action on this preparation.

On the whole sophagus, acetylcholine produced a biphasic contraction which was blocked by cocaine and was partially antagonized by hexamethonium. The fast component of the contraction to acetylcholine was blocked by tubocurarine and was partially antagonized by hyoscine, and the slow component of the contraetion to acetylcholine was blocked by hyoscine and was partially antagonized by tubocurarine. Acetyl--methylcholine produced a monophasic contraction which was blocked by hyoscine and was potentiated by cocaine.

Note:

I wish to thank Dr. F. Alexander, Dr. B. L. Ginsborg and Mr. T. Hassan for helpful suggestions, Miss Anna Clark, Mr. D. Goff and Mr. I. S. Warwick for their careful technical help and Mr. R. C. W. S. Hood for photography.