The functional relationship of the longitudinal and circular muscle of the guinea-pig uterus and human fallopian tube.

Uterine horns from pregnant and non-pregnant guinea-pigs were suspended in Krebs solution and perfused at a constant rate of flow. Contractions of the circular muscle were recorded by monitoring the perfusion pressure. Longitudinal muscle activity was measured by isometric recording of longitudinal tension. This technique was also employed to study the isolated human fallopian tube.It was confirmed that contractions of the two muscle layers in the above tissues could be recorded by the technique employed without significant mechanical interaction. In the guinea-pig uterus the predominant form of spontaneous activity was the almost synchronous contractions of the two muscle layers, with changes in longitudinal tension slightly preceding the changes in perfusion pressure. In contrast, the two muscle layers of the human fallopian tube appear to operate independently. Furthermore the two muscle layers of the guinea-pig uterus reacted in a similar manner to a variety of stimuli. In the human fallopian tube prostaglandin E1 caused an increase in longitudinal tension, with inhibition of the rhythmic changes in perfusion pressure. The functional implications of these findings are discussed.