Regional distribution of sodium--potassium--activated adenosine triphosphatase in the rat gastrointestinal tract.

Several solutes are preferentially absorbed by specific segments of the gastrointestinal tract(l). This variation in the distribution of sites for particular absorptive meclhanisms suggests that the enzymes related to these processes may also be assymmetrically distributed. The observation that ouabain, an inhibitor of sodium-potassium-activated adenosine triphosphatase (Na-K-ATPase) in vitro, inlhibits intestinal transport systems(2,3) suggests that this enzyme may be involved in the active absorption of sodium by the gut. The present study was designedI to test the hlypothesis that the regional distribution of Na-K-ATPase in the gut will correlate witlh physiological information on the sites of preferential absorption of sodium and water.