Renal response to phosphorus deprivation in the isolated rat kidney

In order to study further the adaptation of inorganic phsophate (Pi) reabsorption during phosphorus depletion, Pi transport was measured at three perfusate Pi concentrations in isolated perfused rat kidney preparations, utilizing synthetic albumin-containing cell-free perfusate. With elevation of the perfusate Pi, phosphaturia was significantly less, and absolute Pi reabsorption was significantly greater in kidneys derived from phosphorus-deprived rats than in organs from nondeprived counterparts. Prior parathyroidectomy did not affect the transport of Pi by the isolated kidney preparation. Increasing the perfusate Pi did not diminish hypercalciuria in kidneys from phosphorus-deprived rats. The results indicate that the adaptive response in Pi reabsorption during phosphorus deprivation can be demonstrated independently of the composition of fluid perfusing the kidney. The mechanism underlying the adaptation, however, remains unclarified.