Hypoxia provokes leukotriene-dependent neutrophil sequestration in perfused rabbit hearts

Isolated rabbit hearts were perfused with salt solution containing autologous 111In-labeled neutrophils to determine whether 1) hypoxia provoked myocardial neutrophil sequestration, 2) neutrophil accumulation could be suppressed by inhibition of lipoxygenase and 3) hypoxic myocardium generated radioimmunoassayable leukotriene B4 (LTB4). Whereas accumulation of 111In-labeled neutrophils by normoxic hearts was minimal, induction of acute myocardial hypoxia by perfusion with hypoxic medium caused a rapid uptake of 111In-labeled neutrophils. Sequestered neutrophils were not released during a subsequent 20-min normoxic perfusion period. Hypoxia-induced neutrophil uptake was prevented by nordihydroguaiaretic acid (NDGA) or diethylcarbamazine (DEC), two structurally different inhibitors of lipoxygenase. Although no radioimmunoassayable LTB4 could be detected in neutrophil-free perfusate from normoxic or hypoxic preparations, hypoxia caused an approximate 2-fold increase in myocardial tissue levels of LTB4. Tissue levels of LTB4 reverted to control values after 20 min of normoxic perfusion. Infusion of exogenous LTB4 also provoked myocardial neutrophil uptake. Viewed collectively, these observations suggest that in isolated buffer-perfused rabbit hearts hypoxia induces LTB4 release from resident myocardial cells, which promotes avid neutrophil sequestration.