Proton conductance and intracellular pH recovery from an acid load in chicken enterocytes.
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.
Peral
M J
MJ
Departmento Fisiología y Biología Animal, Facultad de Farmacia, Universidad de Sevilla, Spain.
Ilundáin
A A
AA
D000143:Acids / Q000378:metabolism; D000818:Animals; D000897:Anti-Ulcer Agents / Q000494:pharmacology; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / Q000494:pharmacology; D002645:Chickens; D006863:Hydrogen-Ion Concentration; D007093:Imidazoles / Q000494:pharmacology; D007413:Intestinal Mucosa / Q000378:metabolism*; D007422:Intestines / Q000166:cytology; D007424:Intracellular Fluid / Q000378:metabolism; D017136:Ion Transport; D009550:Nigericin / Q000494:pharmacology; D004369:Pentetic Acid / Q000494:pharmacology; D017494:Proton Pumps / Q000502:physiology*; D014634:Valinomycin / Q000494:pharmacology; D015032:Zinc / Q000494:pharmacology
D000143:Acids; D000897:Anti-Ulcer Agents; D007093:Imidazoles; D017494:Proton Pumps; C035235:Sch 28080; D014634:Valinomycin; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; D004369:Pentetic Acid; D015032:Zinc; D009550:Nigericin