Regulation of Calcium Intestinal Absorption in the Camel Calf (Camelus dromedarius)

Postprandial hypercalcemia and hyperphosphatemia, as well as intestinal calcium (Ca) absorption were measured in 12 newborn camels. They were divided into four groups of three animals. Groups 1 and 2 received an i.v. infusion of synthetic human parathyroid hormone (PTH)/PTH-related peptide (PTHrP) or solvent alone, respectively. At the beginning of infusion, groups 1 and 2 received an oral administration of artificial milk. Groups 3 and 4 received i.v. injections of 1α,25-dihydroxyvitamin D3 (1α,25(OH)2D3) or of solvent, respectively. At the last injection, groups 3 and 4 received an oral administration of SrCl2. PTHrP induced a significant rise in postprandial hypercalcemia and hyperphosphatemia. It had no significant effect on urinary volume or on Ca renal excretion, but it increased phosphorus (P) renal excretion. 1α,25(OH)2D3 induced a significant increase in plasma levels of strontium, Ca and P. 1α,25(OH)2D3 did not induce significant variations on the urinary volume nor on Ca, P, or Sr renal excretion. These results seem to show that PTHrP and 1α,25(OH)2D3 play a major role in bone growth of camel calves.