Calcium Metabolism in the Rat Studied with Calcium45: Effect of Age.

Milhaud, G; Cherian, A. George; Moukhtar, M.S.

doi:10.3181/00379727-114-28684

Cited by 15 publications

(7 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…If this view is correct, bone contribution to fall in plasma calcium following thyroparathyroidectomy decreases with age. This is not surprising since it is well accepted that bone turnover (17) and probably the effect of parathyroid hormone on bone decline with age.…”

Section: Contribution Of Increase In Urinary Calcium Excretion To Falmentioning

confidence: 63%

The Role of Parathyroid Hormone in the Maintenance of Plasma Calcium Levels in Rats

et al. 1974

View full text Add to dashboard Cite

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. The following observations were made. 1) Plasma calcium but not hydroxyproline decreased 3 hr after TPTX. 2) The degree of hypocalcemia was inversely related to age. 3) By 24 hr, urinary hydroxyproline had decreased and plasma calcium fallen further. 4) Plasma calcium and urinary hydroxyproline decreased immediately in immature rats and rats fed a calcium-deficient diet. 5) TPTX acutely enhanced urinary calcium excretion. 6) 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. 7) In animals fed a low-calcium diet only 4% of the fall in plasma calcium was due to increased calciuria. From these findings we conclude that 1) PTH maintains plasma calcium by enhancing calcium transport from bone, resorption of calcified bone matrix and kidney reabsorption of calcium, 2) 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, 3) bone-mediated minute-to-minute regulation of plasma calcium by the hormone may be due instead to calcium transport from bone without osteolysis, and 4) PTHdependent contribution of the kidney to the maintenance of plasma calcium probably increases and surpasses that of bone with age. (Endocrinology 95: 1156(Endocrinology 95: , 1974

show abstract

Section: Contribution Of Increase In Urinary Calcium Excretion To Falmentioning

confidence: 63%

The Role of Parathyroid Hormone in the Maintenance of Plasma Calcium Levels in Rats

et al. 1974

View full text Add to dashboard Cite

show abstract

“…In the adult rat (1 year old) the mass of exchangeable calcium, bone anabolism, intestinal absorption and balance are reduced when com pared to the calcium metabolism of a 2 month old rat [16]. Further more, the constant diminution of serum phosphate accompanying advancing age [15] reduces the availability of phosphate which seems to be more important than calcium for the development of calcergic reactions [7,8,25].…”

Section: Discussionmentioning

confidence: 99%

Influence of Age on Experimental Cutaneous Calcification

Tuchweber¹

1969

Gerontology

View full text Add to dashboard Cite

“…We have previously shown that calcium metabolism can be described in terms of various parameters, which can be calculated from a detailed analysis of the integrated plasma specific activity curve and from the amounts of calcium ingested and excreted by way of urine and feces(4). Furthermore, different experimental conditions were reflected by changes in the values of these parameters-for example rickets (4) and increase in age ( 5). A single tracer dose of Ca45 (50 pC) was injected intravenously 2 hours after the first administration of either TCT or buffer.…”

Section: Laboratoire Des Zsotopes -Znstitut Pasteur Parismentioning

confidence: 99%