Intestinal transport in megacolonic mice. Alterations in sugar absorption.

This study examined jejunal sugar absorption in piebald mice with congenital megacolon and in normal littermates. Transmural potential difference, short-circuit current, and tissue conductance of flat sheets of jejunum set up in flux chambers were significantly greater in the diseased mice compared to normal siblings. In piebald mice, net absorption of 3-o-methylglucose was enhanced due to a significant increase in mucosal-to-serosal flux compared with normal littermates. Stimulation of electrogenic sodium absorption by alanine (10 mM) increased basal short-circuit currents more in piebald tissues than in tissues from normal mice, whereas stimulation of ion transport by carbachol (10 microM) evoked an increase in short-circuit current that was similar in the two groups. Alterations in intestinal mass, morphology, or Na+, K+-ATPase activity could not account for the increase in absorptive function characteristic of piebald mice.