Effect of glucocorticoids on the passive transport of phosphate in different segments of the intestine in the rat.
We investigated the influence of glucocorticoids on phosphate absorption in the duodenum, mid-jejunum, ileum and colon. Phosphate transport, fluid absorption and sodium absorption were determined by the in vivo ligated loop technique. The administration of cortisone stimulated intestinal fluid absorption in each segment of the small intestine, but not in the colon. Cortisone enhanced net sodium absorption in proportion to the increase in fluid absorption. Phosphate was most effectively absorbed in the duodenum and jejunum. Net phosphate absorption in the ileum and colon was negligible. Administration of cortisone stimulated the passive transport of phosphate in each segment of the small intestine studied. The 32Pi absorption was increased 56, 54 and 97% in the duodenum, jejunum and ileum, respectively. There was no apparent stimulation of passive transport of phosphate by cortisone in the colon. Although the exact mechanism is unknown, increased luminal phosphate concentration gradient or enhanced sodium and water absorption after cortisone administration could account for the increase in phosphate transport in the small intestine. However, the effects of these factors vary from segment to segment.
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D003348:Cortisone / Q000494:pharmacology; D005938:Glucocorticoids / Q000494:pharmacology*; D007408:Intestinal Absorption / Q000187:drug effects; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000187:drug effects*; D008297:Male; D010710:Phosphates / Q000493:pharmacokinetics*; D051381:Rats; D011919:Rats, Inbred Strains
D005938:Glucocorticoids; D010710:Phosphates; D003348:Cortisone