Chloride/formate exchange with formic acid recycling: a mechanism of active chloride transport across epithelial membranes

Journal Article · Sun Sep 01 00:00:00 EDT 1985 · Proc. Natl. Acad. Sci. U.S.A.; (United States)

DOI:https://doi.org/10.1073/pnas.82.18.6362· OSTI ID:6169316

Karniski, L P; Aronson, P S

The pathways for transport of Cl/sup -/ and formate in microvillus membrane vesicles isolated from rabbit renal cortex were evaluated. An outward formate gradient stimulated the uptake of /sup 36/Cl/sup -/, and an outward /sup 36/Cl/sup -/ gradient stimulated the uptake of formate, indicating Cl/sup -//formate exchange. In addition, an inside alkaline pH gradient induced the accumulation of formate, consistent with nonionic diffusion of formic acid. Although an inward Na/sup +/ gradient also stimulated uphill formate accumulation, this effect was abolished when ionophores were used to prevent the generation of a transmembrane pH gradient. An inside alkaline pH gradient only minimally stimulated the uptake of /sup 82/Br/sup -/, used as tracer for Cl/sup -/, confirming the absence of appreciable Cl/sup -//OH/sup -/ exchange. However, the same pH gradient in the presence of a physiologic formate concentration (0.2 mM) markedly stimulated /sup 82/Br/sup -/ influx. These data suggest that Cl/sup -//formate exchange with recycling of formic acid by nonionic diffusion is a potential mechanism for active Cl/sup -/ absorption across the luminal membrane in the proximal tubule and perhaps in other epithelia.

• Research Organization: Yale Univ. School of Medicine, New Haven, CT
• OSTI ID: 6169316
• Journal Information: Proc. Natl. Acad. Sci. U.S.A.; (United States), Journal Name: Proc. Natl. Acad. Sci. U.S.A.; (United States) Vol. 82:18; ISSN PNASA
• Country of Publication: United States
• Language: English

Related Subjects

551001* -- Physiological Systems-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ABSORPTION
ANIMAL TISSUES
ANIMALS
ANIONS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BODY
BROMINE 82
BROMINE ISOTOPES
CARBON 14 COMPOUNDS
CARBOXYLIC ACID SALTS
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CELL MEMBRANES
CHARGED PARTICLES
CHLORIDES
CHLORINE 36
CHLORINE COMPOUNDS
CHLORINE ISOTOPES
DAYS LIVING RADIOISOTOPES
DIFFUSION
ELECTRON CAPTURE RADIOISOTOPES
EPITHELIUM
FORMATES
FORMIC ACID
HALIDES
HALOGEN COMPOUNDS
INTERMEDIATE MASS NUCLEI
IONS
ISOTOPE APPLICATIONS
ISOTOPES
KIDNEYS
LABELLED COMPOUNDS
LIGHT NUCLEI
MAMMALS
MEMBRANE TRANSPORT
MEMBRANES
MONOCARBOXYLIC ACIDS
NUCLEI
ODD-ODD NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANS
PH VALUE
PHYSIOLOGY
RABBITS
RADIOISOTOPES
TISSUES
TRACER TECHNIQUES
VERTEBRATES
YEARS LIVING RADIOISOTOPES