Low-protein diet decreases intestinal Na,K-ATPase

Experiments were carried out to examine the long-term effect of dietary protein variations on Na,K-ATPase activity in the intestinal epithelium. Na,K-ATPase activity was studied in rats receiving an isocaloric diet containing 19 % (standard-protein diet) or 9 % (low-protein diet) protein for 7 weeks. The low-protein diet decreased Na,K-ATPase activity in the duodenum but had no significant effect on any other intestinal segments. Mg-ATPase activity was not altered in any segment. In the duodenum, chronic low-protein intake increased the affinity of Na,K-ATPase and decreased Vmax for Na+. The changes in Na,K-ATPase activity in the upper intestinal segment did not reflect hypertrophy, since the low- and standard-protein intake protocols did not alter the protein/DNA ratio. The results suggest that increased protein intake is particularly effective in stimulating duodenal Na,K-ATPase.