Parathyroid hormone and 25-hydroxy vitamin D3: synergistic and antagonistic effects on renal phosphate transport.
The effect on phosphate excretion of graded doses of parathyroid hormone (PTH) and the biologically active vitamin D3 metabolite, 25-hydroxycholecalciferol (25-HCC), administered singly and in combination, were studied in the nonexpanded, vitamin D-depleted thyroparathyroidectomized rat. Infusion of 1 unit of 25-HCC per hour for 6 hours induced an antiphosphaturia only when administered with 0.2 units of PTH per hour, while neither agent alone changed phosphate excretion. A dose of 2.0 units of PTH per hour did not cause phosphaturia unless given with 1 unit of 25-HCC per hour. In pharmacologic dosage (5 units per hour), PTH produced phosphaturia in the absence of the metabolite.
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000097:blood; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D005260:Female; D006887:Hydroxycholecalciferols / Q000494:pharmacology*; D007668:Kidney / Q000378:metabolism*; D010281:Parathyroid Hormone / Q000494:pharmacology*; D010710:Phosphates / Q000097:blood / Q000378:metabolism / Q000652:urine*; D051381:Rats
D006887:Hydroxycholecalciferols; D010281:Parathyroid Hormone; D010710:Phosphates; D002118:Calcium