Unique coronary vasodilator induction by leukotriene D4

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Abstract
Coronary blood flow (CBF) and myocardial contractility decrease markedly in response to intracoronary administration of leukotriene D4 (LTD4). With steady infusion, however, both CBF and contractility escape, approaching preinfusion values despite ongoing LTD4 administration. To clarify the mechanism of this escape, we reinfused plasma from the coronary vein draining the myocardial area receiving LTD4. Introducing this plasma into a coronary artery caused a marked rise in coronary flow for the duration of the plasma infusion. Coronary flow reduction with vasopressin or mechanical occlusion matching that caused by LTD4 failed to elicit vasodilator production. Thus a unique coronary vasodilator factor is induced by LTD4. Whole blood or platelet-rich plasma incubated with LTD4 in vitro produced the same pattern of coronary dilation on intracoronary infusion; LTD4 incubation with platelet-poor plasma failed to elicit a vasodilation. The vasodilator factor is stable and is not potassium, a prostaglandin, catecholamine, histamine, serotonin, adenosine, adenosine diphosphate, or platelet-activating factor. Production of this leukotriene-induced vasodilator factor may account for the escape from LTD4-induced coronary constriction.