Study on Water and Electrolytes Transport in the Rat Intestine

Abstract

In an attempt to clarify water, potassium and sodium transport in the rat intestine, the Na and K equilibrium concentration, electrical potential difference (PD) were measured.
The K efflux and water net flux were also determined respectively. The following results were obtained from the isotonic solution:
(a) K equilibrium concentration in the rat intestine was higher than the serum potassium concentration, particularly at the lower intestine. (b) Na equilibrium concentration was lower than serum sodium level, especially in the colon, (c) PD was largest in the colon, (d) K efflux from glucose-free solution, in which K concentration was 10mM/L was 5.92×10^-6 in jejunum, 2.82×10^-6 in ileum and 1.50×10^-6mM/cm² min in colon. (e) K efflux was significantly influenced by solvent drag in jejunum. (f) net water flux was greater in the colon in comparison with small intestine. It is conculuded that potassium appears to be passively absorbed and the amount of K absorption was greater in the upper intestine. Active potassium secretion appears to be available in large intestine. In addition, sodium absorption is presumably active process and the amount of absorption is greater in the colon.