Influence of vitamin D status and chronic administration on the renal tubular effects of 1,25-dihydroxy vitamin D3.
Previous studies from this laboratory have demonstrated that the acute infusion of the vitamin D3 derivative, 1,25-dihydroxy vitamin D3 (1,25(OH)2D3) is antiphosphaturic when administered with small "permissive" amounts of parathyroid hormone (PTH). To determine the effect of chronic administration of this metabolite, studies were performed in both vitamin D-deficient (-D) and vitamin D-fed (+D) rats which had been pretreated with 1,25(OH)2D3 for 6 days and then infused with either the metabolite alone, the metabolite with a small "permissive" dose of parathyroid hormone (PTH) or neither. The results indicate that in the -D animals, 1,25(OH)2D3 infusion alone results in antiphosphaturia without the presence of PTH. However, in the +D rats, PTH was required, despite 1,25(OH)2D3 pretreatment, for the acute infusion of the metabolite to enhance phosphate reabsorption. Thus, both vitamin D and parathyroid status are important in determining the effect of 1,25(OH)2D3 on the renal tubular transport of phosphate.
D000818:Animals; D002117:Calcitriol / Q000494:pharmacology*; D002118:Calcium / Q000097:blood; D007684:Kidney Tubules / Q000502:physiology*; D010281:Parathyroid Hormone / Q000494:pharmacology; D010710:Phosphates / Q000097:blood / Q000652:urine; D051381:Rats; D014808:Vitamin D Deficiency / Q000503:physiopathology
D010281:Parathyroid Hormone; D010710:Phosphates; D002117:Calcitriol; D002118:Calcium