Developmental changes in rabbit proximal straight tubule paracellular permeability

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Abstract

The early proximal tubule preferentially reabsorbs organic solutes and bicarbonate over chloride ions, resulting in a luminal fluid with a higher chloride concentration than that in blood. From this late proximal tubular fluid, one-half of NaCl reabsorption by the adult proximal tubule is active and transcellular and one-half is passive and paracellular. The purpose of the present in vitro microperfusion study was to determine the characteristics of passive chloride transport and permeability properties of the adult and neonatal proximal straight tubules (PST). In tubules perfused with a late proximal tubular fluid, net passive chloride flux was 131.7 ± 37.7 pmol·mm-1·min-1 in adult tubules and -17.1 ± 23.3 pmol·mm-1min-1 in neonatal proximal tubules (P < 0.01). Chloride permeability was 10.94 ± 5.21 × 10-5 cm/s in adult proximal tubules and -1.26 ± 1.84 × 10-5 cm/s in neonatal proximal tubules (P < 0.05). Thus neonatal PST have a chloride permeability not different from zero and have no net passive chloride transport. Bicarbonate permeability is also less in neonates than adults in this segment (-0.07 ± 0.03 × 10-5 vs. 0.93 ± 0.27 × 10-5 cm/s, P < 0.01). Neonatal PST have higher sodium-to chloride and bicarbonate-to-chloride permeability ratios than adult PST. However, mannitol and sucrose permeabilities were not different in adult proximal tubules and neonatal PST. Transepithelial resistance was measured using current injection and cable analysis. The resistance was 6.7 ± 0.7 Ω·cm2 in adult tubules and 11.3 ± 1.4 Ω·cm2 in neonatal PST (P < 0.01). In conclusion, there are significant maturational changes in the characteristics of the PST paracellular pathway affecting transport in this nephron segment.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Renal Physiology
Volume283
Issue number3 52-3
StatePublished - Sep 2002

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Chlorides
Permeability
Rabbits
Bicarbonates
Sodium Bicarbonate
Nephrons
Mannitol
Sodium Chloride
Sucrose
Ions
Injections

Keywords

  • Bicarbonate permeability
  • Chloride permeability
  • Chloride transport
  • Passive transport
  • Renal development
  • Tight junction

ASJC Scopus subject areas

  • Physiology

Cite this

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title = "Developmental changes in rabbit proximal straight tubule paracellular permeability",
abstract = "The early proximal tubule preferentially reabsorbs organic solutes and bicarbonate over chloride ions, resulting in a luminal fluid with a higher chloride concentration than that in blood. From this late proximal tubular fluid, one-half of NaCl reabsorption by the adult proximal tubule is active and transcellular and one-half is passive and paracellular. The purpose of the present in vitro microperfusion study was to determine the characteristics of passive chloride transport and permeability properties of the adult and neonatal proximal straight tubules (PST). In tubules perfused with a late proximal tubular fluid, net passive chloride flux was 131.7 ± 37.7 pmol·mm-1·min-1 in adult tubules and -17.1 ± 23.3 pmol·mm-1min-1 in neonatal proximal tubules (P < 0.01). Chloride permeability was 10.94 ± 5.21 × 10-5 cm/s in adult proximal tubules and -1.26 ± 1.84 × 10-5 cm/s in neonatal proximal tubules (P < 0.05). Thus neonatal PST have a chloride permeability not different from zero and have no net passive chloride transport. Bicarbonate permeability is also less in neonates than adults in this segment (-0.07 ± 0.03 × 10-5 vs. 0.93 ± 0.27 × 10-5 cm/s, P < 0.01). Neonatal PST have higher sodium-to chloride and bicarbonate-to-chloride permeability ratios than adult PST. However, mannitol and sucrose permeabilities were not different in adult proximal tubules and neonatal PST. Transepithelial resistance was measured using current injection and cable analysis. The resistance was 6.7 ± 0.7 Ω·cm2 in adult tubules and 11.3 ± 1.4 Ω·cm2 in neonatal PST (P < 0.01). In conclusion, there are significant maturational changes in the characteristics of the PST paracellular pathway affecting transport in this nephron segment.",
keywords = "Bicarbonate permeability, Chloride permeability, Chloride transport, Passive transport, Renal development, Tight junction",
author = "Raymond Quigley and Michel Baum",
year = "2002",
month = "9",
language = "English (US)",
volume = "283",
journal = "American Journal of Physiology - Heart and Circulatory Physiology",
issn = "0363-6135",
publisher = "American Physiological Society",
number = "3 52-3",

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T1 - Developmental changes in rabbit proximal straight tubule paracellular permeability

AU - Quigley, Raymond

AU - Baum, Michel

PY - 2002/9

Y1 - 2002/9

N2 - The early proximal tubule preferentially reabsorbs organic solutes and bicarbonate over chloride ions, resulting in a luminal fluid with a higher chloride concentration than that in blood. From this late proximal tubular fluid, one-half of NaCl reabsorption by the adult proximal tubule is active and transcellular and one-half is passive and paracellular. The purpose of the present in vitro microperfusion study was to determine the characteristics of passive chloride transport and permeability properties of the adult and neonatal proximal straight tubules (PST). In tubules perfused with a late proximal tubular fluid, net passive chloride flux was 131.7 ± 37.7 pmol·mm-1·min-1 in adult tubules and -17.1 ± 23.3 pmol·mm-1min-1 in neonatal proximal tubules (P < 0.01). Chloride permeability was 10.94 ± 5.21 × 10-5 cm/s in adult proximal tubules and -1.26 ± 1.84 × 10-5 cm/s in neonatal proximal tubules (P < 0.05). Thus neonatal PST have a chloride permeability not different from zero and have no net passive chloride transport. Bicarbonate permeability is also less in neonates than adults in this segment (-0.07 ± 0.03 × 10-5 vs. 0.93 ± 0.27 × 10-5 cm/s, P < 0.01). Neonatal PST have higher sodium-to chloride and bicarbonate-to-chloride permeability ratios than adult PST. However, mannitol and sucrose permeabilities were not different in adult proximal tubules and neonatal PST. Transepithelial resistance was measured using current injection and cable analysis. The resistance was 6.7 ± 0.7 Ω·cm2 in adult tubules and 11.3 ± 1.4 Ω·cm2 in neonatal PST (P < 0.01). In conclusion, there are significant maturational changes in the characteristics of the PST paracellular pathway affecting transport in this nephron segment.

AB - The early proximal tubule preferentially reabsorbs organic solutes and bicarbonate over chloride ions, resulting in a luminal fluid with a higher chloride concentration than that in blood. From this late proximal tubular fluid, one-half of NaCl reabsorption by the adult proximal tubule is active and transcellular and one-half is passive and paracellular. The purpose of the present in vitro microperfusion study was to determine the characteristics of passive chloride transport and permeability properties of the adult and neonatal proximal straight tubules (PST). In tubules perfused with a late proximal tubular fluid, net passive chloride flux was 131.7 ± 37.7 pmol·mm-1·min-1 in adult tubules and -17.1 ± 23.3 pmol·mm-1min-1 in neonatal proximal tubules (P < 0.01). Chloride permeability was 10.94 ± 5.21 × 10-5 cm/s in adult proximal tubules and -1.26 ± 1.84 × 10-5 cm/s in neonatal proximal tubules (P < 0.05). Thus neonatal PST have a chloride permeability not different from zero and have no net passive chloride transport. Bicarbonate permeability is also less in neonates than adults in this segment (-0.07 ± 0.03 × 10-5 vs. 0.93 ± 0.27 × 10-5 cm/s, P < 0.01). Neonatal PST have higher sodium-to chloride and bicarbonate-to-chloride permeability ratios than adult PST. However, mannitol and sucrose permeabilities were not different in adult proximal tubules and neonatal PST. Transepithelial resistance was measured using current injection and cable analysis. The resistance was 6.7 ± 0.7 Ω·cm2 in adult tubules and 11.3 ± 1.4 Ω·cm2 in neonatal PST (P < 0.01). In conclusion, there are significant maturational changes in the characteristics of the PST paracellular pathway affecting transport in this nephron segment.

KW - Bicarbonate permeability

KW - Chloride permeability

KW - Chloride transport

KW - Passive transport

KW - Renal development

KW - Tight junction

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M3 - Article

VL - 283

JO - American Journal of Physiology - Heart and Circulatory Physiology

JF - American Journal of Physiology - Heart and Circulatory Physiology

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