Modulation of receptor mediated leukotriene release in the perfused heart

The chemotactic peptide n-formyl-methionyl-leucyl-phenylalanine (FMLP) induces peptide leukotriene release at concentrations of 20-25 pmol/ml 3 min after the start of FMLP infusion. FMLP-induced leukotriene release in rabbit hearts is not blocked by the Leukotriene Receptor antagonist FPL-55712 at concentrations that totally antagonize the hemodynamic effects of exogenously infused peptide leukotrienes. Moreover, propyl gallate, a Lipoxygenase inhibitor, does not block FMLP-induced leukotriene release. However, the chemotactic peptide antagonist (Boc-Phe-Leu-Phe-Leu-Phe-OH) totally antagonized FMLP-induced leukotriene release suggesting that the release is via a different mechanism, possibly a receptor mediated event.