May 1, 1968
British journal of pharmacology and chemotherapy
The striped external muscle of the isolated guinea-pig oesophagus is insensitive to drugs and the lumen does not seem to be patent; thus the preparation does not respond to drugs until they have penetrated the external muscle and stimulated the intramural nerves or the plain muscle of the muscularis mucosae. The innervation of the external muscle of the guinea-pig oesophagus is not blocked by hexamethonium and is apparently without ganglia, so a stimulant of ganglion-cells produces a contraction of the muscularis mucosae only, which is distinguishable from a contraction of the external muscle. Further-more, the external muscle and the muscularis mucosae can be separated, so that the actions of drugs on the muscularis mucosae in situ can be compared with those on the separated muscularis mucosae (Bartlet, 1968a, b). Hence the structure of the guinea-pig oesophagus makes it a suitable preparation for analysing the actions of drugs on the intramural nervous plexuses and muscularis mucosae of the alimentary tract, and a description of the actions of 5-hydroxytryptamine (5-HT) and histamine on this preparation follows.