Transient Secretion of Phosphate in the Mammalian Kidney

Renal transtubular flux of electrolytes in dogs with special reference to calcium

“…This they interpreted to mean that phosphorus secretion can occur in the dog under special conditions of phosphate loading. Inasmuch as the work reported by Rees et al (1959) and by us indicates a small flux, it seems likely that the net secretion of phosphate observed by Carrasquer & Brodsky (1959) was a function of the transient, but large, load of phosphate presented to the kidney.…”

“…We see no way of reconciling this conclusion with the report of Nicholson & Shepherd (1959), who studied the effect of tubular poisons on phosphate excretion in dogs and concluded that this ion is secreted actively by the distal tubule. Conceivably, as was implied by Carrasquer & Brodsky (1959), the mammalian kidney can, but does not normally, secrete phosphate. Moreover, in recent publications Samiy, Hirsch, Ramsay, Giordano & Merrill (1960b) and also Pullman, Lavender, Aho & Rasmussen (1960) reported that they were unable to find any evidence of tubular secretion of phosphate in dogs.…”

“…This they interpreted as the site of principal reabsorption of this electrolyte. Carrasquer & Brodsky (1959) recovered in the urine a greater fraction of injected phosphate than of injected creatinine. This they interpreted to mean that phosphorus secretion can occur in the dog under special conditions of phosphate loading.…”

“…Conceivably, as was implied by Carrasquer & Brodsky (1959), the mammalian kidney can, but does not normally, secrete phosphate. Moreover, in recent publications Samiy, Hirsch, Ramsay, Giordano & Merrill (1960b) and also Pullman, Lavender, Aho & Rasmussen (1960) reported that they were unable to find any evidence of tubular secretion of phosphate in dogs.…”

A micropuncture study of renal phosphate transport in rats with chronic renal failure and secondary hyperparathyroidism.

“…This difference between the two groups is all the more striking in view of the fact that plasma phosphate was much higher in the normal phosphateloaded rats than in the NX rats. Such high plasma levels might be expected to promote secretion of phosphate (12,(24)(25)(26)(27) A second possibility is that addition of phosphate occurred along the collecting ducts of the hyperparathyroid NX rats. The presence of a renal secretory mechanism for phosphate has been a controversial subject for many years, but has been reported in a few clearance studies in phosphate-loaded normal dogs (25,26) and man (27).…”