Ontogeny of water transport in the rabbit proximal tubule

Research output: Contribution to journalReview article

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Abstract

Water transport across cell membranes is a fundamental biological problem. In the kidney, many nephron segments have mechanisms for transporting large quantities of water with minimal energy input. The proximal tubule reabsorbs two-thirds of the glomerular filtrate with a small transepithelial osmotic gradient as the driving force. In the adult proximal tubule, this is accomplished by the expression of aquaporin 1 (AQP1), the water channel located on the apical and basolateral membranes of the proximal tubule. The neonatal tubule has a much lower expression of AQP1, yet can still transport water with a small osmotic gradient. Thus, tubule properties other than AQP1 expression must allow for this to occur. There are two primary differences that account for this unexpectedly high osmotic water permeability of the neonatal proximal tubule. First, the lipid membrane of the neonatal tubule is more fluid than the adult tubule and therefore a larger fraction of the water can pass through the lipid bilayer. The second property is the fact that the neonatal tubule cells have a smaller cell volume, and thus, the intracellular compartment provides less resistance for the movement of water. This review will discuss postnatal maturation of proximal tubule water transport.

Original languageEnglish (US)
Pages (from-to)1089-1094
Number of pages6
JournalPediatric Nephrology
Volume18
Issue number11
DOIs
StatePublished - Nov 1 2003

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Keywords

  • In vitro microperfusion
  • Osmotic water permeability
  • Stop-flow kinetics

ASJC Scopus subject areas

  • Pediatrics, Perinatology, and Child Health
  • Nephrology

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