Metabolic disturbances and short-circuit current across intestinal wall of rat

Abstract

The potential difference, short-circuit current, and resistance were determined across the wall of the rat small intestine under a variety of conditions in vitro. With the normal Ringer's fluid on both sides of the wall, the average values obtained were 7.6 mv for the potential difference, 120 µa/cm² for the short-circuit current, and 63 ohm-cm² for the resistance. The potential difference and short-circuit current were found to vary roughly in parallel except upon application of low Na concentration. Reversible reduction was induced in both potential difference and short-circuit current by 1 mm sodium azide, 0.1 mm phlorizin, and 0.1 mm dinitrophenol applied on the mucosal side. Withdrawal of glucose from the mucosal side induced a decline of both potential difference and short-circuit current, and the decline was partially recovered by substitution of galactose for glucose at the same concentration but not of fructose or sorbitol. The short-circuit current was shown to depend upon the glucose concentration on the mucosal side in accordance with Michaelis-Menten kinetics, the K_m value being 72 mg/100 ml. On the other hand the short-circuit current was linearly related to the Na concentration in Ringer's fluid. At low concentration of Na the resistance increased more than could be accounted for by the decrease of conductivity of low Na Ringer's fluid.