Water Exchange Between Intestinal Contents, Tissues and Blood

Abstract

Analysis of mucosal and muscle tissue fractions and of venous blood from loops of dog ileum lavaged with D2O-enriched fluids demonstrate that (a) the average mucosal (D2O) is always lower than that of the luminal fluids, being only 25% of the lavage fluid concentration even after 2 hours; and (b) the venous blood (D2O) from such loops is never more than 5% of the lavage fluid (D2O), and at all times is less than the average (D2O) of either the mucosa or muscle tissue fractions. Apparently there are 2 and probably 3 rate-limiting steps in the exchange of water between intestinal luminal fluids and capillary blood.