The relationship between superoxide generation, cytochrome b and oxygen in activated neutrophils.

The O2 affinity for O2.- generation (i.e. O2 tension at which 50% of the O2-saturated activity was observed) by rat neutrophils activated by the chemotactic peptide (N-formyl-methionyl-leucyl-phenylalanine) plus cytochalasin B was measured as 5.4 microM (+/- 1.4, n = 5). Similarly, the O2 tension at which cytochrome b was oxidized to 50% of its aerobic steady-state level in activated cells was 4.7 microM (+/- 1.0, n = 3): in non-activated cells the corresponding value for cytochrome b oxidation was 11.4 microM (+/- 2.8, n = 3). It is proposed that O2 depletion at inflammatory sites may limit oxidant generation by activated neutrophils and thus reduce oxidant damage to surrounding tissues.