In Vivo Intestinal Calcium Absorption in Infant Rats: Influence of Methylprednisolone and Vitamin D

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Abstract
The influence of pharmacological doses of methylprednisolone and vitamin D on in vivo absorption of Ca from the samll intestine was studied in suckling (14-15 day old), weanling (21-22 day old) and adolescent (42 day old) rats. I.m. injection of methylprednisolone (2.5 mg/100 g body wt daily for 5 days) suppressed absorption of Ca from the jejunum + ileum of the suckling rats only. Both lumen-to-mucosa and mucosa-to-lumen fluxes of Ca were lower in the treated than in the control suckling rats, indicating that the permeability of the mucosal membrane to Ca was decreased with injection of methylprednisolone. This suggested an effect on a passive process of Ca transport rather than on the vitamin D-dependent mechanism of Ca absorption. This effect is compatable with findings of other studies showing that, in glucocorticoid treated rats, the metabolism of vitamin D is not altered in a way to decrease absorption of Ca from the small intestine. Oral administration of vitamin D (5000 IU/100 g body wt daily for 3 days) to suckling and weanling rats, did not enhance the in vivo absorption of Ca in the small intestine, an observation similar to a previous in vivo study in adolescent rats.