Effect of various vitamin D analogs on plasma calcium and phosphorus and intestinal calcium absorption in fed and unfed American eels, Anguilla rostrata.

Injection of about 1 ng/g body wt per day of either vitamin D3 or 1,25-(OH)2-vitamin D3 for 7 days induces hypercalcemia and hyperphosphatemia in fed American eels, Anguilla rostrata, but only hyperphosphatemia in unfed eels. These same analogs also stimulated the uptake of 45Ca from intestinal sacs in situ. The vitamin D3 appeared to be relatively more effective than the 1,25-(OH)2D3 metabolite and chlorpromazine inhibited the effect of vitamin D3 on intestinal calcium uptake. 7-Dehydrocholesterol, vitamin D2, and 24,25-(OH)2D3 did not stimulate hypercalcemia, hyperphosphatemia, or intestinal calcium uptake.