Pharmacological modification of leukotriene release and coronary constrictor effect in cardiac anaphylaxis

The modification of anaphylactic release of leukotriene (LT) C4-like immunoreactivity from isolated guinea pig hearts and of LT-induced coronary constriction by the muscarinic receptor against methacholine and by various exogenous prostaglandins (PG) was investigated. The vasodilators PGI2 and PGE2 as well as the vasoconstrictors PGD2, PGF2alpha, and 11,9-epoxymethano-PGH2, a PG endoperoxide analogue with biological properties similar to thromboxane (TX) A2, inhibited the anaphylactic coronary constriction without affecting release of LTC4-like immunoreactivity. On the other hand, the increased anaphylactic LT release in the presence of methacholine was not paralleled by more pronounced coronary constriction after challenge. The results suggest that the coronary constrictor effect of endogenous LT is modified by the drugs used by direct vascular effects and/or effects on other anaphylactic mediators.