The role of parathyroid hormone in the maintenance of plasma calcium levels in rats

D. N. Kalu, A. Hadji-Georgopoulos, M. G. Sarr, B. A. Solomon, G. V. Foster

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Investigations were carried out in rats to determine the relative roles of kidney and bone in the regulation of plasma calcium by parathyroid hormone (PTH). The effects of endogenous PTH were studied by parathyroid ablation. Parathyroid glands were removed by thyroparathyroidectomy (TPTX) since parathyroidectomy appears to release calcitonin and thyroidectomy itself does not alter plasma calcium levels. Changes in plasma calcium, urinary calcium and urinary hydroxyproline were determined 3 hr or 24 hr after TPTX in rats of varying ages and in animals fed a calcium deficient diet for 30 days to enhance PTH secretion and bone turnover. Plasma calcium but not hydroxyproline decreased 3 hr after TPTX. The degree of hypocalcemia was inversely related to age. By 24 hr, urinary hydroxyproline had decreased and plasma calcium fallen further. Plasma calcium and urinary hydroxyproline decreased immediately in immature rats and rats fed a calcium deficient diet. TPTX acutely enhanced urinary calcium excretion. The increase in urine calcium accounted for 8, 12, 45 and 67% of the fall in plasma calcium in 45, 134, 221 and 241 g rats, respectively. In animals fed a low calcium diet only 4% of the fall in plasma calcium was due to increased calciuria. From these findings it is concluded that PTH maintains plasma calcium by enhancing calcium transport from bone, resorption of calcified bone matrix and kidney reabsorption of calcium, PTH dependent bone resorption does not play an appreciable role in the acute control of plasma calcium except when the rate of bone turnover is high, bone mediated minute to minute regulation of plasma calcium by the hormone may be due instead to calcium transport from bone without osteolysis, and PTH dependent contribution of the kidney to the maintenance of plasma calcium probably increases and surpasses that of bone with age.

Original languageEnglish (US)
Pages (from-to)1156-1165
Number of pages10
JournalEndocrinology
Volume95
Issue number4
StatePublished - 1974
Externally publishedYes

Fingerprint

Parathyroid Hormone
Maintenance
Calcium
Hydroxyproline
Bone and Bones
Bone Remodeling
Bone Resorption
Diet
Kidney
Parathyroidectomy
Osteolysis
Bone Matrix
Parathyroid Glands
Hypocalcemia
Thyroidectomy
Calcitonin

ASJC Scopus subject areas

  • Endocrinology
  • Endocrinology, Diabetes and Metabolism

Cite this

Kalu, D. N., Hadji-Georgopoulos, A., Sarr, M. G., Solomon, B. A., & Foster, G. V. (1974). The role of parathyroid hormone in the maintenance of plasma calcium levels in rats. Endocrinology, 95(4), 1156-1165.

The role of parathyroid hormone in the maintenance of plasma calcium levels in rats. / Kalu, D. N.; Hadji-Georgopoulos, A.; Sarr, M. G.; Solomon, B. A.; Foster, G. V.

In: Endocrinology, Vol. 95, No. 4, 1974, p. 1156-1165.

Research output: Contribution to journalArticle

Kalu, DN, Hadji-Georgopoulos, A, Sarr, MG, Solomon, BA & Foster, GV 1974, 'The role of parathyroid hormone in the maintenance of plasma calcium levels in rats', Endocrinology, vol. 95, no. 4, pp. 1156-1165.
Kalu DN, Hadji-Georgopoulos A, Sarr MG, Solomon BA, Foster GV. The role of parathyroid hormone in the maintenance of plasma calcium levels in rats. Endocrinology. 1974;95(4):1156-1165.
Kalu, D. N. ; Hadji-Georgopoulos, A. ; Sarr, M. G. ; Solomon, B. A. ; Foster, G. V. / The role of parathyroid hormone in the maintenance of plasma calcium levels in rats. In: Endocrinology. 1974 ; Vol. 95, No. 4. pp. 1156-1165.
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