Interaction between neutrophils and pig coronary artery increases histamine contractions

In the present study we investigated the possible role of neutrophils and the endothelium in the induction of hyperreactivity of pig coronary arteries to histamine. Histamine caused a dose-dependent contraction of isolated pig coronary arteries. The maximal contraction to histamine was reduced in preparations from which the endothelium had been removed. Pre-incubation of intact coronary arteries with isolated neutrophils had no influence on the contractile response to histamine. However, when the same experiments were performed with coronary arteries without endothelium, the maximal contraction to histamine was increased. Incubation with scavengers and inhibitors of the enzymes, lipoxygenase or cyclo-oxygenase, provided evidence for a role of lipoxygenase products in the induction of hyperreactivity to histamine by neutrophils in the pig coronary artery.