Platelet-activating factor stimulates the release of atrial natriuretic factor from the rat heart

Atrial natriuretic factor (alpha-ANF (99-126), ANF) is released from atrial cells following atrial distension, myocardial infarction and periods of ischaemic or tachyarrhythmias. In this report we demonstrate that platelet-activating factor (PAF) stimulates ANF release from the isolated perfused rat heart and following i.v. injection to conscious unrestrained rats. ANF release peaked at 145% above baseline following injection of 2.5 nmol PAF into the isolated heart while administration of 2 nmol in vivo produced a 135% increase in plasma ANF levels. The PAF receptor antagonist BN52021 (10 mumol/l) attenuated this stimulated release, with the results suggesting a role for PAF in ANF secretion following release from damaged myocardium or as a humoral factor originating from the kidney.