Ion transport in the gut.

The in vitro preparation of the small intestine of the rat is well suited for studies of ion transport. Data from this preparation indicate that the passage of water and electro-lytes across the intestinal epithelium depends on active transport. Glycolysis seems to be involved as a source of energy for the transport of ions from the mucosal to the serosal aspect of the intestinal wall. LITERATURE on ion transport from the intestinal tract has expanded to the extent that a brief review of the subject must be limited to selected aspects. In the following discussion, attention will be directed primarily to the transport of ions from the small intestine of the rat, and major emphasis will be on data obtained from in vitro preparations. The in vitro preparation of the small intestine of the rat is a highly desirable preparation for the study of ion transport for a number of reasons: (1) functional activity seems to be little affected by removing the intestine from the body if care is taken in handling the gut, and it is quickly transferred to a favorable environment; (2) transport is maintained with little diminution in capacitv for several hours; (3) the amount of fluid transported is sufficiently great to permit an accurate analysis of its composition; (4) the composition of the fluid transported varies greatly in different portions of the small in