Common channels for water and protons at apical and basolateral cell membranes of frog skin and urinary bladder epithelia. Effects of oxytocin, heavy metals, and inhibitors of H(+)-adenosine triphosphatase

Journal Article · Mon Apr 01 00:00:00 EST 1991 · Journal of General Physiology; (United States)

DOI:https://doi.org/10.1085/jgp.97.4.749· OSTI ID:5270524

Harvey, B; Lacoste, I; Ehrenfeld, J ^[1]

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1. Commissariat a l'Energie Atomique, Villefranche-sur-mer (France)

We have compared the response of proton and water transport to oxytocin treatment in isolated frog skin and urinary bladder epithelia to provide further insights into the nature of water flow and H+ flux across individual apical and basolateral cell membranes. In isolated spontaneous sodium-transporting frog skin epithelia, lowering the pH of the apical solution from 7.4 to 6.4, 5.5, or 4.5 produced a fall in pHi in principal cells which was completely blocked by amiloride, indicating that apical Na+ channels are permeable to protons. When sodium transport was blocked by amiloride, the H+ permeability of the apical membranes of principal cells was negligible but increased dramatically after treatment with antidiuretic hormone (ADH). In the latter condition, lowering the pH of the apical solution caused a voltage-dependent intracellular acidification, accompanied by membrane depolarization, and an increase in membrane conductance and transepithelial current. These effects were inhibited by adding Hg2+ (100 microM) or dicyclohexylcarbodiimide (DCCD, 10(-5) M) to the apical bath. Net titratable H+ flux across frog skin was increased from 30 +/- 8 to 115 +/- 18 neq.h-1.cm-2 (n = 8) after oxytocin treatment (at apical pH 5.5 and serosal pH 7.4) and was completely inhibited by DCCD (10(-5) M). The basolateral membranes of the principal cells in frog skin epithelium were found to be spontaneously permeable to H+ and passive electrogenic H+ transport across this membrane was not affected by oxytocin. Lowering the pH of the basolateral bathing solution (pHb) produced an intracellular acidification and membrane depolarization (and an increase in conductance when the normal dominant K+ conductance of this membrane was abolished by Ba2+ 1 mM). These effects of low pHb were blocked by micromolar concentrations of heavy metals (Zn2+, Ni2+, Co2+, Cd2+, and Hg2+).

• OSTI ID: 5270524
• Journal Information: Journal of General Physiology; (United States), Vol. 97:4; ISSN 0022-1295
• Country of Publication: United States
• Language: English

Related Subjects

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
CELL MEMBRANES
PERMEABILITY
ENZYME INHIBITORS
BIOLOGICAL EFFECTS
METALS
OXYTOCIN
PROTONS
MEMBRANE TRANSPORT
WATER
ATP-ASE
BLADDER
ELECTROLYTES
EPITHELIUM
FROGS
IMIDES
IN VITRO
SKIN
ACID ANHYDRASES
AMPHIBIANS
ANIMAL TISSUES
ANIMALS
AQUATIC ORGANISMS
BARYONS
BODY
CELL CONSTITUENTS
ELEMENTARY PARTICLES
ELEMENTS
ENZYMES
FERMIONS
HADRONS
HORMONES
HYDROGEN COMPOUNDS
HYDROLASES
MEMBRANES
NUCLEONS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
OXYGEN COMPOUNDS
PEPTIDE HORMONES
PHOSPHOHYDROLASES
PITUITARY HORMONES
PROTEINS
TISSUES
URINARY TRACT
VERTEBRATES
560300* - Chemicals Metabolism & Toxicology