Sensitivity of the kidney to parathyroid hormone and its relationship to serum calcium in the hamster.

Abstract

The sensitivity of renal conservation of calcium to parathyroid hormone (PTH) was investigated in acutely parathyroidectomized hamsters, by detenu in ing the dose-response characteristics of urinary excretion of calcium as influenced by parathyroid extract (PTE). A linear decrease in urinary calcium excretion was observed between dosages of 0.8–10 U PTE/100 g body wt, the latter dose restoring calcium excretion to levels present in parathyroid intact animals. A linear increase in serum calcium occurred within this same dose range with 10 U raising serum calcium by 2 mg/100 ml beyond preinjection levels. Larger amounts of hormone (30–200 U) produced no further significant effect on urinary excretion of calcium, and resulted in only a small, further increase in serum calcium which appeared to be dose-dependent. Changes in serum calcium were inversely related and significantly (p < 0.001) correlated with changes in urinary calcium. These findings demonstrate that renal conservation of calcium in the hamster ...