Longitudinal variation in the activities of mucosal enzymes in the small intestine of suckling rats.

The extent of positional variation in mucosal enzyme activity along the small intestine was investigated in 14-day-old suckling rats. Samples were taken from ten equally spaced sites along the intestine in 11 rat pups and the activities of the enzymes alkaline phosphatase, neutral aminopeptidase, gamma-glutamyl transferase, lactase and sucrase were measured. All the enzymes except sucrase were subject to considerable positional variation. Alkaline phosphatase and aminopeptidase activities were distributed throughout the intestine, with a broad maximum in the distal intestine. Lactase was also broadly distributed but with greatest activity in the mid intestine. gamma-glutamyl transferase exhibited a novel profile, with a very high proportion of the total activity (78%) present in the distal intestine. Sucrase was essentially absent throughout the intestine.