Expression of a novel sodium-hydrogen exchanger in the gastrointestinal tract and kidney.

We have recently cloned a novel Na+/H+ exchanger (NHE-2) from rat small intestinal cDNA library. The present report characterizes the expression of (NHE-2) mRNA in the rat small intestine, stomach, and kidney using Northern blot analysis and in situ hybridization techniques. NHE-2 mRNA was detected in the surface epithelium of the stomach, villus but not crypt epithelial cells of the small intestine and in the distal convoluted, but not in the proximal tubules of the kidney. This distribution suggests a functional role in the transport of sodium across the apical membrane of the gastrointestinal tract and the kidney.