Effects of Parathyroid Extract on Removal of Sr89, Ca45, and P32 by Hemodialysis from Conscious Calves

Abstract

Effects of parathyroid hormone on mobilization of Sr, Ca, and P were studied by hemodialysis. Nine fasted calves were randomly assigned to one of three treatment groups. Treatments were: (A) thyroparathyroidectomy, (B) thyroparathyroidectomy plus PTE, and (C) control mock-operated calves. Strontium-89, Ca45, and P32 were injected intravenously 48 hr before the 16-hr dialysis period. Surgery was performed 22 hr before dialysis. The PTE was given intramuscularly at 2-hr intervals, beginning at the initiation of dialysis (6.6 USP units/ kilogram/day).Treatments did not significantly affect the accumulation of total Ca or P in the dialyzing baths. However, the Sr89/Ca45 ratio of activities in the baths was significantly increased by PTE administration (P<.05). Reduction of plasma Ca45 activity during dialysis averaged (A) 28%, (B) 53%, and (C) 51% (A vs. B + C, P<0.05). Treatment of the animals with PTE significantly reduced Sr89 in epiphyseal bone (P<0.05). All treatments resulted in an incorporation of Ca45 into the rib epiphyses. The PTE group (B) had the greatest reduction of Sr89 activity and also the greatest incorporation of Ca45 into the rib epiphyses during dialysis. Accumulation of Sr89 and Ca45 in the dialyzing baths, reduction of Ca45 activity in the plasma, and the relative Sr89 and Ca45 activities of the rib epiphyses indicate that PTE administration resulted in a release of Sr89 from the epiphyses, with a preferential incorporation of Ca45 during dialysis.