Jejunal transport properties of piebald mouse model for Hirschsprung's disease.

Unidirectional fluxes of alanine, methionine, and Na were measured in jejunal segments from 3- to 4-wk-old normal (N) mice or mice with congenital (P) or induced (I) megacolon in the absence of electrochemical gradients. Short-circuit currents were 286.8 +/- 16.3 and 302.1 +/- 32.6 mu A/cm2 for P and I mice, respectively, and were approximately 1.5-2 times greater than in N mice. Tissue conductances averaged 42.3 +/- 0.6 and 39.3 +/- 3.4 mS/cm2 for P and I mice, respectively, and were twice those found in N mice. Net Na absorption was 2-3 times greater in P than N mice and was increased by addition of alanine. Alanine and methionine were actively absorbed and the net fluxes of alanine were 2-3 times greater in p and I mice than in normals. Unidirectional alanine influx was enhanced in P and I mice. Jmax of 9.7 +/- 2.6 and 14.2 +/- 1.0 micro M x cm-2 x h-1 were obtained for N and P mice, respectively. These results show that the transport properties of jejunal mucosa of mice with megacolon differ from those of N mice. Mice with megacolon absorb alanine and Na at a greater rate than N mice and the enhanced amino acid absorptive rate can be explained by an increased alanine influx, probably due to an increased number of active transport carriers.