Na+-K+)-stimulated adenosinetriphosphatase in isolated intestinal villus tip and crypt cells

The migration of intestinal epithelial cells from the crypt area to the villus tip is associated with progressive differentiation of these cells. The distribution of (Na+K+) stimulated adenosinetriphosphatase ((Na+K+)-ATPase; EC 3.6.1.3) along the intestinal villus may have functional as well as developmental implications. To define this distribution, rat jejunal and ileal segments were incubated in vitro with a citrate solution that dissociates epithelial cells sequentially from villus tip to crypt area. ATPase activity in cell collections from villus tips and crypt areas were compared. The specific activity of (Na+K+)-ATPase was higher in the villus tip than in the crypt cells of both jejunum and ileum. Crypt cell (Na+K+)-ATPase activity in the jejunum and ileum were similar. Thus, (Na+K+)-ATPase activity of villus tip cells in the jejunum was greater than in the ileum. There was no difference in villus tip and crypt cell Mg2+-ATPase activity in either jejunum or ileum. The steep gradient for (Na+K+)-ATPase along the intestinal villus may signify an improtant difference in Na+ transport between the villus tip and crypt area. The higher level of (Na+K+)-ATPase activity in the jejunal villi is consistent with the more important role of the jejunum in Na+ and substrate-linked Na+ transport.