Characteristics of the paracellular pathway of rabbit cortical collecting duct

Journal Article · Sat Oct 01 04:00:00 EDT 1988 · American Journal of Physiology; (USA)

OSTI ID:6252698

Warden, D H; Schuster, V L; Stokes, J B ^[1]

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1. Univ. of Iowa, Iowa City (USA) Veterans Administration Medical Center, Iowa City, IA (USA)

The nature of the paracellular pathway of the rabbit cortical collecting duct (CCD) was examined under conditions designed to eliminate all cellular ion transport. Transcellular conductive pathways were blocked by addition of amiloride and Ba{sup 2+} to the perfusate. Cl self-exchange was eliminated by removing Cl from the bath solution, and HCO{sub 3} transport was eliminated by omitting HCO{sub 3} and CO{sub 2} from the solutions. The residual transepithelial conductance (G{sub T}) and radioisotopic tracer flux under these conditions probably occur via the paracellular pathway. The G{sub T} measured in nontransporting CCD bathed in NaCl solutions was 1.1-1.2 mS/cm{sup 2}. When {sup 22}Na or {sup 36}Cl was replaced by a less mobile ion, the G{sub T} decreased by an amount commensurate with the decrease in solution conductivity. The Na-to-Cl permeability ratio determined by NaCl dilution voltages ranged from 0.55 to 0.82. An independent estimate of paracellular selectivity was obtained by comparing the lumen-to-bath tracer rate coefficients for {sup 22}Na (k{sub Na}) and {sup 36}Cl (k{sub Cl}). The ratio k{sub Na}:k{sub Cl} was 0.75. These observations suggest that the paracellular pathway displays a Na:Cl permselectivity not substantially different from the ratio of their mobilities in water (0.65). The authors conclude that the paracellular conductance of CCD is nonselective in character and {approximately}1-2 mS/cm{sup 2} in magnitude.

• OSTI ID: 6252698
• Journal Information: American Journal of Physiology; (USA), Journal Name: American Journal of Physiology; (USA) Vol. 255:4; ISSN 0002-9513; ISSN AJPHA
• Country of Publication: United States
• Language: English

Related Subjects

551001* -- Physiological Systems-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ALKALI METAL ISOTOPES
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
BODY
CHARGED PARTICLES
CHLORINE 36
CHLORINE ISOTOPES
DIURETICS
DRUGS
ELECTRON CAPTURE RADIOISOTOPES
IONS
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
KIDNEYS
LIGHT NUCLEI
MAMMALS
MEMBRANE TRANSPORT
NUCLEI
ODD-ODD NUCLEI
ORGANS
PERMEABILITY
PHYSIOLOGY
RABBITS
RADIOISOTOPES
SODIUM 22
SODIUM ISOTOPES
VERTEBRATES
YEARS LIVING RADIOISOTOPES