Fluid propulsion by cat intestinal segments under conditions requiring hydrostatic work

Abstract

The intrinsic ability of duodenal, jejunal, and ileal segments of cats to propel fluid by doing hydrostatic work was investigated in vitro. Segments of terminal ileum demonstrated two functional states. In the net propulsive state, propulsive complexes occurred at an average interval of 7.9 min. These complexes consisted of an initial phase characterized by the simultaneous ejection of equal fluid volumes from both ends of a segment at a frequency of 8/min and a second phase that ejected a net volume of fluid from the aboral end. Ileal segments not in the net propulsive state demonstrated complexes consisting only of the 8/min ejections. Segments of proximal duodenum and midjejunum failed to produce net propulsion when evaluated under similar conditions. These results indicate that 1) ileal segments can intrinsically produce net fluid transport in the aboral direction when hydrostatic work is required for propulsion, 2) propulsive activity intrinsic to ileal segments is regulated by intrinsic control mechanisms having an effective oscillatory period of 8 min, and 3) basic differences exist in the intrinsic control structures between ileal and other intestinal regions.