New analysis for the study of the muscle function in the human oesophagus.

The aim was to further develop a method for studying the active and passive tissue properties in the human oesophagus. An impedance planimetric probe with a bag for distension was placed in the distal oesophagus in 14 healthy volunteers. Distension was done at an infusion rate of 25 mL min(-1) with and without the administration of the antimuscarinic drug butylscopolamine. The flow was reversed when moderate pain was experienced by the subject. The total and the passive tension showed an exponential behaviour as function of the change in radius. The active tensions increased until they reached a maximum point. The active tension decreased after the maximum until the distension was stopped shortly after due to the pain. The change in tension during distension-induced contractions (the afterload) was plotted as function of the precontraction radius (the preload). The human oesophagus behaves in a manner known from in vitro studies on muscle strips and exhibits a muscle diagram similar to that in the heart, i.e. the larger the initial muscle length during distension (within limits), the greater the contraction force.