THE RENAL EXCRETION OF CALCIUM AND STRONTIUM
In a series of exploratory experiments designed to study the influence of age, sex, ammonium-chloride feeding, and dietary Ca and P content on the excretion of Sr and Ca by the rat kidney. It was noticed that low discrimination between Sr and Ca was always associated with high Ca excretion rates and vice- versa. A Sr/Ca excretion model was formulated which suggested an experimental approach to the study of this relationship. The postulates and development of the model are outlined. According to this model, any reduction in the efficiency of Ca reabsorption shouid result in increased Ca and Sr excretion rates and a reduction in the OR/sub (urine/filtrate)/. In order to reduce the efficiency of Ca reabsorption and thus test the model, stable Ca solutions were injected intravenously into 2 goats at rates sufficient to cause overloading of the tubular reabsorptive mechanism for Ca. The anticipated fall in the OR/sub (urine/ filtrate) to unity, associated with the greatly augmented Ca excretion rate, was observed following the start of stable Ca infusion in the initial experiments. Next, inulin clearance and plasma ultrafiltration techniques were added to the procedure of 3 more experiments to make possible the determination of Ca and Sr glomerular filtration rates and calculation of the efficiency of Ca and Sr reabsorption by the renal tubules. As expected, the efficiency of tubular reabsorption of both Sr and Ca fell when stable Ca (and when stable Sr) was infused. A precise mathematical model relating renal discrimination and Ca excretion rate was formulated using data supplied in a separate paper on the dependence of Sr reabsorptive efficiency on that of Ca. (M.P.G.)
- Research Organization:
- Originating Research Org. not identified
- NSA Number:
- NSA-17-021426
- OSTI ID:
- 4694287
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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