title: Platelet-Mediated Cardioprotective Effect Against Ischemia-Reperfusion Injury in Isolated Rat Hearts: Role of Platelet Number and Contribution of Supernatant of Aggregated Platelets.
abstract: BACKGROUND: Previous studies have documented cardioprotective effects of circulating platelets after reperfusion injury. The present study was designed to examine the role of platelet number and contribution of platelet-released mediators in the platelet supernatant in cardioprotection against ischemia-reperfusion-induced myocardial dysfunction. METHODS AND RESULTS: Isolated buffer-perfused (constant volume) Sprage-Dawley rat hearts were subjected to 25 minutes of global ischemia followed by 30 minutes of reperfusion. Ischemia-reperfusion resulted in myocardial dysfunction, indicated by an increase in coronary perfusion pressure and left ventricular end-diastolic pressure, and a decrease in developed left ventricular pressure. Perfusion of hearts with washed rat platelets (10(3)-2.2 x 10(7) cells/mL) significantly (P <.01) attenuated these indices of myocardial dysfunction upon ischemia-reperfusion in a concentration-dependent manner. A cardioprotective effect of platelets was observed at a concentration as low as 10(5) platelets/mL. Similar cardioprotection was seen in hearts perfused with the supernatant of aggregated platelets. CONCLUSIONS: These observations indicate that the platelet-mediated cardioprotective effect against ischemia-reperfusion in vitro is concentration dependent, and platelet-released mediators in the platelet supernatant are protective against ischemia-reperfusion injury.
authors.affiliation: Departments of Medicine and Pediatrics, College of Medicine, Gainesville, Florida, USA
authors.initials: B
authors.lastname: Yang
authors.initials: P
authors.lastname: Mehta
authors.initials: JL
authors.lastname: Mehta