Amiloride-sensitive Na+/H+ exchange in human neutrophils: mechanism of activation by chemotactic factors.
The cytoplasmic pH (pHi) of human blood neutrophils was measured using trapped carboxyfluorescein derivatives. Cells were acid-loaded using propionate or by pretreatment with NH4+. Acid-loaded cells were found to regain near-normal pHi by means of a Na+-dependent process. A concomitant Na+ uptake was recorded as a change in cell volume. Both events were amiloride-sensitive, indicating involvement of a Na+/H+ antiport. Activation of Na+/H+ exchange was also observed with chemotactic factors. Studies of the pHi-dependence of the H+ extrusion rate indicate that chemotactic factors increase the [H+i] sensitivity of the antiport.
D000584:Amiloride / Q000494:pharmacology*; D000641:Ammonia / Q000494:pharmacology; D002352:Carrier Proteins / Q000097:blood*; D002794:Choline / Q000494:pharmacology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology*; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism*; D011719:Pyrazines / Q000494:pharmacology*; D017923:Sodium-Hydrogen Exchangers
D002352:Carrier Proteins; D011719:Pyrazines; D017923:Sodium-Hydrogen Exchangers; D009240:N-Formylmethionine Leucyl-Phenylalanine; D000641:Ammonia; D000584:Amiloride; D002794:Choline