Abstract
The effect of K+ on the absorption of acetanilide, salicylamide, sulfisoxazole, and quinine from rat small intestine was studied using principally the in situ perfusion technique. 1) The intestinal absorption of those drugs was considerably reduced by K+. 2) The decrease in the blood flow of the small intestine, which is induced by the depression of cardiac action based on the absorption of K+ from the K or Na-K phosphate buffer solution, markedly inhibits the in situ intestinal absorption of the drugs. 3) It is suggested that the decrease in the intestinal tissue respiration in the presence of K+ produces a depression of functional integrity of the intestinal membrane resulting in the histological changes of the intestinal mucosa, and that a decrease in the absorptive surface area based on the morphological changes in the villi somewhat reduces the absorption of the drugs.