Renal tubular transport of inorganic sulfate

Abstract

The urinary excretion of radiosulfate by the dog was investigated after a rapid injection into one renal artery. Radiosulfate appeared in the urine before simultaneously injected creatinine. After the plasma sulfate concentration had been elevated, the precession of sulfate over creatinine disappeared. Glucose infusion, which competes with sulfate reabsorption, decreased precession; phlorhizin, which blocks glucose transport, increased the precession. In the chicken, compounds injected into a leg vein perfuse only the tubules of the ipsilateral kidney on the first circulation. Before and after sulfate loading, precession of radiosulfate was seen, and the influx of sulfate increased after loading. There was no consistent relationship between the increase in the plasma sulfate concentration and the increase in influx. The proportion of excreted sulfate which entered the urine by transtubular flux decreased with the increase in the plasma sulfate concentration. This may explain the diminished precession of radiosulfate seen in the dog after loading with sulfate.