Antagonism of vasoconstriction induced by platelet‐activating factor in guinea‐pig perfused hearts by selective platelet‐activating factor receptor antagonists

Abstract

Platelet‐activating factor (Paf) is a potent coronary vasoconstrictor in rat, guinea‐pig, dog and pig. The present study investigated the mechanism and duration of action of Paf in guinea‐pig isolated, Krebs‐perfused hearts. Dose‐related and sustained decreases in cardiac contractility and increases in coronary perfusion pressure were elicited by bolus doses of Paf (0.3–100 pmol). Platelet‐activating factor (30 pmol) induced increases in the production of immunoreactive thromboxane B2 (TXB2), leukotriene B4 (LTB4) and LTC4, but not 6‐keto‐prostaglandin F1α (6‐keto‐PGF1α). In addition, the release of leukotriene‐like material following Paf was observed using on‐line superfusion bioassay. The ..