Paracellular pathway of rabbit cortical collecting tubule (CCT): a high resistance, non-selective barrier

Conference · Sat Mar 01 04:00:00 EST 1986 · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)

OSTI ID:5450908

Warden, D H; Schuster, V L; Stokes, J B

Previous studies have suggested that the paracellular pathway of CCT is Cl selective. We reassessed this issue under conditions in which the cellular Na and K conductive pathways were blocked by lumen amiloride (50 ..mu..M) and Ba/sup + +/ (4 mM). The residual transepithelial conductance (G/sub T/, 1.10 +- 0.09 mS cm/sup -2/) is a reasonable estimate of the paracellular conductance. Three independent assessments of the barrier selectivity were used. First, the effect of symmetrical replacement of Na (TMA, bis (2-hydroxy ethyl) dimethylammonium) or Cl (NO/sub 3/, gluconate) on G/sub T/ was determined. All test solutions decreased G/sub T/, and in each case the decrease could be accounted for by the lower conductivity of the test solution relative to NaCl. Thus, the pathway does not select one cation or one anion over another. Second, lumen-to-bath /sup 22/Na and /sup 36/Cl fluxes were measured with 0 Cl/0 HCO/sub 3/ bath to eliminate cellular Cl flux. The ratio J/sub Na/J/sub Cl/ (0.75 +- 0.14) was not different from the ratio of Na/Cl mobilities in water (0.65), and the sum of the calculated partial ionic conductances of Na and Cl adequately approximated the measured G/sub T/. Third, NaCl concentration was sequentially lowered in lumen or bath. In the presence of bath ouabain, P/sub Na//P/sub Cl/, calculated from dilution voltages was 0.67 +- .02. The paracellular pathway of CCT is non-selective for anions over cations.

• Research Organization: Univ. of Iowa, Iowa City
• OSTI ID: 5450908
• Report Number(s): CONF-8604222-
• Conference Information: Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Journal Volume: 45:3
• Country of Publication: United States
• Language: English

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550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ALKALI METAL ISOTOPES
ALKALI METALS
ALKALINE EARTH METAL COMPOUNDS
ANIMAL TISSUES
ANIMALS
ANIONS
BARIUM COMPOUNDS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
BIOLOGICAL PATHWAYS
BODY
CATIONS
CHARGED PARTICLES
CHLORINE
CHLORINE 36
CHLORINE ISOTOPES
DIURETICS
DRUGS
ELECTRON CAPTURE RADIOISOTOPES
ELEMENTS
EPITHELIUM
HALOGENS
IONS
ISOTOPE APPLICATIONS
ISOTOPES
KIDNEYS
LIGHT NUCLEI
MAMMALS
MEMBRANE TRANSPORT
METALS
NONMETALS
NUCLEI
ODD-ODD NUCLEI
ORGANS
RABBITS
RADIOISOTOPES
SODIUM
SODIUM 22
SODIUM ISOTOPES
TISSUES
TRACER TECHNIQUES
TUBULES
VERTEBRATES
YEARS LIVING RADIOISOTOPES