Changes in inorganic phosphate excretion induced by renal arterial infusion of calcium

Abstract

Calcium chloride in varying concentrations was infused at a slow and constant rate into the renal artery of one kidney in the dog. The opposite kidney served as a control. In 20 experiments, the mean glomerular filtration rate and effective renal plasma flow diminished in the infused relative to the noninfused kidneys. Mean phosphate excretion was decreased in the infused relative to the control kidneys by both a fall in filtered phosphate and a rise in the net tubular reabsorption of phosphate. Mean calcium, sodium, and water excretion did not change in the infused relative to the control kidneys during calcium infusion. The data indicate that hypercalcemia acts directly on the kidney to decrease phosphate excretion by decreasing glomerular filtration rate and increasing net tubular reabsorption of phosphate.