Maturation of rat proximal tubule chloride permeability

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Abstract

We have previously shown that neonate rabbit tubules have a lower chloride permeability but comparable mannitol permeability compared with adult proximal tubules. The surprising finding of lower chloride permeability in neonate proximals compared with adults impacts net chloride transport in this segment, which reabsorbs 60% of the filtered chloride in adults. However, this maturational difference in chloride permeability may not be applicable to other species. The present in vitro microperfusion study directly examined the chloride and mannitol permeability using in vitro perfused rat proximal tubules during postnatal maturation. Whereas there was no maturational change in mannitol permeability, chloride permeability was 6.3 ± 1.3 × 10-5 cm/s in neonate rat proximal convoluted tubule and 16.1 ± 2.3 × 10-5 cm/s in adult rat proximal convoluted tubule (P < 0.01). There was also a maturational increase in chloride permeability in the rat proximal straight tubule (5.1 ± 0.6 × 10-5 cm/s vs. 9.3 ± 0.6 × 10-5 cm/s, P < 0.01). There was no maturational change in bicarbonate-to-chloride permeabilities (P HCO3/PCl) in the rat proximal straight tubules (PST) and proximal convoluted tubules (PCT) or in the sodium-to-chloride permeability (PNa/PCl) in the proximal straight tubule; however, there was a significant maturational decrease in proximal convoluted tubule P Na/ PCl with postnatal development (1.31 ± 0.12 in neonates vs. 0.75 ± 0.06 in adults, P < 0.001). There was no difference in the transepithelial resistance measured by current injection and cable analysis in the PCT, but there was a maturational decrease in the PST (7.2 ± 0.8 vs. 4.6 ± 0.1 Ω · cm2, P < 0.05). These studies demonstrate there are maturational changes in the rat paracellular pathway that impact net NaCl transport during development.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Volume289
Issue number6 58-6
DOIs
StatePublished - Dec 2005

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Chlorides
Permeability
Mannitol
Bicarbonates
Sodium Chloride
Rabbits
Injections

Keywords

  • Mannitol permeability
  • Paracellular pathway

ASJC Scopus subject areas

  • Physiology

Cite this

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title = "Maturation of rat proximal tubule chloride permeability",
abstract = "We have previously shown that neonate rabbit tubules have a lower chloride permeability but comparable mannitol permeability compared with adult proximal tubules. The surprising finding of lower chloride permeability in neonate proximals compared with adults impacts net chloride transport in this segment, which reabsorbs 60{\%} of the filtered chloride in adults. However, this maturational difference in chloride permeability may not be applicable to other species. The present in vitro microperfusion study directly examined the chloride and mannitol permeability using in vitro perfused rat proximal tubules during postnatal maturation. Whereas there was no maturational change in mannitol permeability, chloride permeability was 6.3 ± 1.3 × 10-5 cm/s in neonate rat proximal convoluted tubule and 16.1 ± 2.3 × 10-5 cm/s in adult rat proximal convoluted tubule (P < 0.01). There was also a maturational increase in chloride permeability in the rat proximal straight tubule (5.1 ± 0.6 × 10-5 cm/s vs. 9.3 ± 0.6 × 10-5 cm/s, P < 0.01). There was no maturational change in bicarbonate-to-chloride permeabilities (P HCO3/PCl) in the rat proximal straight tubules (PST) and proximal convoluted tubules (PCT) or in the sodium-to-chloride permeability (PNa/PCl) in the proximal straight tubule; however, there was a significant maturational decrease in proximal convoluted tubule P Na/ PCl with postnatal development (1.31 ± 0.12 in neonates vs. 0.75 ± 0.06 in adults, P < 0.001). There was no difference in the transepithelial resistance measured by current injection and cable analysis in the PCT, but there was a maturational decrease in the PST (7.2 ± 0.8 vs. 4.6 ± 0.1 Ω · cm2, P < 0.05). These studies demonstrate there are maturational changes in the rat paracellular pathway that impact net NaCl transport during development.",
keywords = "Mannitol permeability, Paracellular pathway",
author = "Michel Baum and Raymond Quigley",
year = "2005",
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journal = "American Journal of Physiology - Heart and Circulatory Physiology",
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T1 - Maturation of rat proximal tubule chloride permeability

AU - Baum, Michel

AU - Quigley, Raymond

PY - 2005/12

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N2 - We have previously shown that neonate rabbit tubules have a lower chloride permeability but comparable mannitol permeability compared with adult proximal tubules. The surprising finding of lower chloride permeability in neonate proximals compared with adults impacts net chloride transport in this segment, which reabsorbs 60% of the filtered chloride in adults. However, this maturational difference in chloride permeability may not be applicable to other species. The present in vitro microperfusion study directly examined the chloride and mannitol permeability using in vitro perfused rat proximal tubules during postnatal maturation. Whereas there was no maturational change in mannitol permeability, chloride permeability was 6.3 ± 1.3 × 10-5 cm/s in neonate rat proximal convoluted tubule and 16.1 ± 2.3 × 10-5 cm/s in adult rat proximal convoluted tubule (P < 0.01). There was also a maturational increase in chloride permeability in the rat proximal straight tubule (5.1 ± 0.6 × 10-5 cm/s vs. 9.3 ± 0.6 × 10-5 cm/s, P < 0.01). There was no maturational change in bicarbonate-to-chloride permeabilities (P HCO3/PCl) in the rat proximal straight tubules (PST) and proximal convoluted tubules (PCT) or in the sodium-to-chloride permeability (PNa/PCl) in the proximal straight tubule; however, there was a significant maturational decrease in proximal convoluted tubule P Na/ PCl with postnatal development (1.31 ± 0.12 in neonates vs. 0.75 ± 0.06 in adults, P < 0.001). There was no difference in the transepithelial resistance measured by current injection and cable analysis in the PCT, but there was a maturational decrease in the PST (7.2 ± 0.8 vs. 4.6 ± 0.1 Ω · cm2, P < 0.05). These studies demonstrate there are maturational changes in the rat paracellular pathway that impact net NaCl transport during development.

AB - We have previously shown that neonate rabbit tubules have a lower chloride permeability but comparable mannitol permeability compared with adult proximal tubules. The surprising finding of lower chloride permeability in neonate proximals compared with adults impacts net chloride transport in this segment, which reabsorbs 60% of the filtered chloride in adults. However, this maturational difference in chloride permeability may not be applicable to other species. The present in vitro microperfusion study directly examined the chloride and mannitol permeability using in vitro perfused rat proximal tubules during postnatal maturation. Whereas there was no maturational change in mannitol permeability, chloride permeability was 6.3 ± 1.3 × 10-5 cm/s in neonate rat proximal convoluted tubule and 16.1 ± 2.3 × 10-5 cm/s in adult rat proximal convoluted tubule (P < 0.01). There was also a maturational increase in chloride permeability in the rat proximal straight tubule (5.1 ± 0.6 × 10-5 cm/s vs. 9.3 ± 0.6 × 10-5 cm/s, P < 0.01). There was no maturational change in bicarbonate-to-chloride permeabilities (P HCO3/PCl) in the rat proximal straight tubules (PST) and proximal convoluted tubules (PCT) or in the sodium-to-chloride permeability (PNa/PCl) in the proximal straight tubule; however, there was a significant maturational decrease in proximal convoluted tubule P Na/ PCl with postnatal development (1.31 ± 0.12 in neonates vs. 0.75 ± 0.06 in adults, P < 0.001). There was no difference in the transepithelial resistance measured by current injection and cable analysis in the PCT, but there was a maturational decrease in the PST (7.2 ± 0.8 vs. 4.6 ± 0.1 Ω · cm2, P < 0.05). These studies demonstrate there are maturational changes in the rat paracellular pathway that impact net NaCl transport during development.

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