| Abstract: | The stimulation of polymorphonuclear leukocytes (PMNs) by phorbol-12-myristate-13-acetate in the presence of sodium fluoride caused the release of protons into the reaction medium concomitant with the generation of superoxide anions. The rates of oxygen consumption and proton release due to the metabolic burst were 16.3 +/- 3.5 and 10.2 +/- 1.1 nmol/min/10(7) cells respectively. When the superoxide anions were trapped with cytochrome c, the proton release was increased (35.8 +/- 0.5 nmol/min/10(7) cells) until the cytochrome c was reduced. Since the protons released from the activated cells would be consumed by the generated superoxide anions in the extracellular medium, the net amount of the protons released was 3-4-fold greater than that observed in the absence of extracellular cytochrome c. The increased proton release may be coupled to increased cellular respiration, since the inhibition of the respiratory burst with deoxyglucose, p-chloromercuribenzoic acid or chlorpromazine decreased the proton release. Amiloride (2 mM) inhibited the proton release by up to 40%. These observations suggest that some mechanisms other than a Na+/H+ antiport and carbon dioxide diffusion could be transporting the H+ generated in the cytosol of the activated PMNs. |
