Effect of hypophysectomy on intestinal phosphate absorption in rats.

Intestinal active and passive transport of phosphate (Pi) was studied in hypophysectomized (HX) and intact rats using the in situ intestinal loop technique. Hypophysectomy resulted in a significant reduction of total Pi absorption under active transport conditions. However, when transport data were expressed on the basis of mucosal mass, the reduction was not apparent. Under passive transport conditions, net Pi absorption was lower in the HX rats even after correction for the decrease of mucosal mass. Administration of bovine growth hormone (bGH) did not change the intestinal Pi absorption in the HX rats. These results indicate that a decrease in mucosal mass following hypophysectomy is one of the factors that causes a decrease of intestinal Pi absorption.