Electrogenic H+ pathway contributes to stimulus-induced changes of internal pH and membrane potential in intact neutrophils: role of cytoplasmic phospholipase A2.

摘要: The potential role of cytosolic phospholipase A2 (cPLA2) in the regulation electrogenic arachidonic acid (AA)-activatable H+ translocator neutrophils was investigated. (1) trifluoromethyl ketone analogue arachidonate (AACOCF3), a newly developed selective blocker cPLA2, inhibited both N-formylmethionyl-leucylphenylalanine (fMLP)- and phorbol-ester-induced rheogenic efflux (K0.5 approximately 5 microM) abrogated stimulus-triggered release AA from these cells. drug failed to reduce fMLP-evoked Ca2+ signal or protein tyrosine phosphorylation did not affect activity kinase C. By using patch-clamp technique we verified that agent interfere with voltage- pH-dependent activation conductance peritoneal macrophages therefore is direct channel itself. AACOCF3, however, slightly decreased AA-induced stimulation currents. We conclude AA, liberated by agonist-induced activator conductance. (2) AACOCF3 inhibit superoxide generation, indicating cPLA2 may be prerequisite for turning on NADPH oxidase. (3) Since neither generation oxidase, nor basal stimulated Na+/H+ exchange (the predominant acid-eliminating mechanism) were influenced drug, could use address whether fact opens plays any physiological during neutrophils. Stimulus-induced alkalinization smaller, whereas depolarization became larger, presence AACOCF3. Stimulated does contribute intracellular pH (pHi) homoeostasis membrane changes intact