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Proton conductance and intracellular pH recovery from an acid load in chicken enterocytes.
Author(s) -
Peral M J,
Ilundáin A A
Publication year - 1995
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1995.sp020655
Subject(s) - nigericin , valinomycin , chemistry , extracellular , intracellular ph , proton transport , cytosol , biophysics , intracellular , potassium , sodium , proton , gentisic acid , inorganic chemistry , biochemistry , membrane potential , membrane , biology , physics , organic chemistry , quantum mechanics , salicylic acid , enzyme
1. Chicken enterocytes present a Na(+)‐independent proton transport mechanism involved in pHi recovery from an acid load. In the current study the nature of this proton transport system is investigated. 2. The pHi of acid‐loaded cells increased when transferred to Na(+)‐free, pH 7.4 buffers, both at 6 and 65 mM extracellular potassium concentration. Addition of nigericin accelerated the rate of cell alkalinization. 3. When acid‐loaded cells were transferred to a Na(+)‐free, pH 6.5 buffer, the cells acidified further, regardless of the extracellular potassium concentration. The addition of nigericin increased the rate of acidification at 6 mM K+ but produced an alkalinization at 65 mM K+. 4. The rate of the Na(+)‐independent regulatory cell alkalinization was inhibited by SCH 28080, DCCD, NBD‐Cl, rotenone or Zn2+. Addition of valinomycin reversed the inhibition induced by SCH 28080, DCCD and NBD‐Cl but not that induced by Zn2+ or rotenone. Zn2+ inhibition was abolished by the metal chelator DTPA. 5. Cytosolic acidification increased the rate of Na(+)‐independent regulatory cell alkalinization. 6. The results suggest that the Na(+)‐independent proton transport system is a Zn(2+)‐sensitive proton‐conducting pathway which is regulated by the cytosolic proton concentration.