Effect of hypercalcaemia on tubular calcium and phosphate transport
Kövér, G.
Acta Physiologica Academiae Scientiarum Hungaricae 45(1-2): 95-107
1974
ISSN/ISBN: 0001-6756 PMID: 4470859 Document Number: 81842
Known quantities of 45Ca2+, 32PO3- and 3H-methoxyinulin were injected into segments of the tubule (early, midand terminal proximal and distal tubule) during mannitol diuresis and sustained hypercalcemia in rats. It was shown that Ca2+ ions were reabsorbed along the entire nephron; PO3- ions were reabsorbed only in the distal tubule but not in the accessible portion of the proximal tubule. Hypercalcemia induced by the infusion of CaCl2 resulted in diminished reabsorption of Ca along the entire nephron and vigorous reabsorption of phosphate in the proximal tubule and the loop of Henele. Elevated serum Ca level failed to affect distal tubular phosphate reabsorption. The same mechanism is responsible for the regulation of Ca reabsorption along the entire nephron. It appears that reabsorption of phosphate in the proximal tubule and loop of Henle is a function of intracellular Ca concentration that changes in parallel with the serum Ca level.