The share of lipoxygenase in the antimycin-resistant oxygen uptake of intact rabbit reticulocytes.

The endogenous oxygen uptake of rabbit reticulocyte-rich red cell suspensions obtained by bleeding anaemia of rabbits amounted to 7.85 +/- 0.87 mumoles/h . ml of packed cells and was inhibited by antimycin A to 77.2 +/- 1.1%. The antimycin A-resistant oxygen uptake was further inhibited by the lipoxygenase inhibitors salicylhydroxamic acid, 5,8,11,14-eicosatetraynoic acid, nordihydroguaiaretic acid, 4-nitrocatechol or propylgallate by about 20-30% corresponding to 5-7% of the total oxygen uptake. The effects of the lipoxygenase inhibitors were most pronounced during the first period of bleeding anaemia (5th-9th day). 3-amino-1,2,4-triazole inhibited another part of the non-respiratory oxygen uptake and acted additively to 5,8,11,14-eicosatetraynoic acid; the two inhibitors together caused inhibition by one-half. Influx of calcium ions mediated by the ionophore A 23187 led to a two-fold increase in the non-respiratory oxygen uptake which was mainly due to stimulation of the lipoxygenase reaction. The rate of the lipoxygenase-mediated oxygen uptake was sufficient for a complete dioxygenation of the polyenoic fatty acids present in mitochondrial phospholipids during the maturational degradation of mitochondria in reticulocytes.