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The actions of Paf‐acether (platelet‐activating factor) on guinea‐pig isolated heart preparations

1 Paf‐acether (platelet‐activating factor) is a phospholipid capable of stimulating platelets to release their granular contents and cause platelet aggregation. When Paf‐acether was administered to isolated heart preparations from normal guinea‐pigs there was a significant concentration‐dependent reduction in coronary flow and contractile force. The high concentration of Paf‐acether was equally effective in reducing these cardiac parameters in the presence of atropine. 2 The non‐acetylated Paf‐acether analogue, 2‐lyso Paf‐acether, the enantiomer, and a closely related phospholipid 1,α‐lysophosphatidylcholine palmitoyl, did not affect coronary flow and contractile force, indicating the specificity of Paf‐acether. 3 These data demonstrate a potent effect of Paf‐acether on cardiac function. Whether or not these effects are direct or mediated through generation of endogenous mediators remains to be established.