Intrarenal phosphate reabsorption: role of nephron heterogeneity.

Abstract

The possibility that phosphate handling may differ between superficial and deep nephrons has been suggested by several investigators over the past 15 years, to explain the discrepancy between phosphate delivery to the distal tubule of superficial nephrons and phosphate excretion in the urine (1, 2). Subsequent micropuncture studies have confirmed this notion. During phosphate conservation (by TPTX), phosphate reabsorption was enhanced in deep nephron proximal tubules (3), whereas, when the excretion of phosphate was high, phosphate reabsorption was relatively greater in superficial nephrons (4, 5). However, the role of nephron heterogeneity in the regulation of phosphate homeostasis was not clear (6). Moreover, in contrast to the in vivo micropuncture experiments, in vitro studies using isolated, perfused tubule segments failed to find any differences in phosphate transport between superficial and deep nephrons (7, 8). To help resolve some of the controversy, this review will highlight recent findings from our laboratory regarding phosphate transport in superficial and deep nephrons and the response to regulators of phosphate reabsorption, which will point to the importance of nephron heterogeneity in the renal handling of phosphate.KeywordsParathyroid HormoneProximal TubulePhosphate TransportPhosphate HomeostasisPhosphate ReabsorptionThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.