Active chloride transport during intestinal secretion

¹ Department of Physiology, The George Washington University Medical School, Washington, D. C.

Characteristically water and chloride ion are absorbed from isotonic saline solutions placed in the in situ jejunal loop of the anesthetized dog. The direction of the water and chloride movement can be reversed by the administration of a cholinergic drug or by the addition of substituted phenols to the isotonic solution bathing the mucosal surface. During such secretion the movement of chloride occurs against a concentration gradient. The transmural electrical potential difference indicates that the lumen is negative with respect to the serosal surface during secretion; thus chloride is also moving against an electrical potential gradient. The calculated concentration of chloride in the fluid moving through the membrane during secretion is higher than the chloride concentration in extracellular fluid which indicates that solvent drag is not responsible for the chloride movement. Therefore active transport of chloride occurs during intestinal secretion.

Note:
With the Technical Assistance of J. S. McNeil