Neutrophils increase histamine contractions in pig coronary artery: a role for lipoxygenase products

The possible role of neutrophils and the endothelium in the induction of hyperreactivity of the pig coronary artery to histamine was studied. In pig isolated coronary arteries histamine caused a concentration-dependent contraction; maximal contraction to histamine, however, was reduced in endothelium-denuded arteries. Pre-incubation of intact coronary arteries with isolated neutrophils did not affect the contractile response to histamine, while pre-incubation of endothelium-denuded arteries induced a hyperreactivity to histamine. This induction of hyperreactivity to histamine by neutrophils in pig coronary arteries seems to be mediated by lipoxygenase products, since it could be prevented by pre-incubation of the preparations with lipoxygenase inhibitors, but not with inhibitors of cyclo-oxygenase or with scavengers.