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Platelet-Mediated Cardioprotective Effect Against Ischemia-Reperfusion Injury in Isolated Rat Hearts: Role of Platelet Number and Contribution of Supernatant of Aggregated Platelets

Departments of Medicine and Pediatrics, College of Medicine, University of Florida, Veterans Affairs Medical Center, Gainesville, Florida

Paulette Mehta

Departments of Medicine and Pediatrics, College of Medicine, University of Florida, Veterans Affairs Medical Center, Gainesville, Florida

Jawahar L. Mehta

Departments of Medicine and Pediatrics, College of Medicine, University of Florida, Veterans Affairs Medical Center, Gainesville, Florida

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 the contribution of platelet-released mediators in the platelet superna tant in cardioprotection against ischemia-reperfusion-induced myocardial dysfunction.

Methods and Results: Isolated buffer-perfused (constant volume) Sprague-Dawley rat hearts were subjected to 25 minutes of global ischemia followed by 30 minutes of reperfu sion. Ischemia-reperfusion resulted in myocardial dysfunction, indicated by an increase in coronary perfusion pressure and left ventricular end-diastolic pressure, and a decrease in de veloped left ventricular pressure. Perfusion of hearts with washed rat platelets (10³-2.2 x 107 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 10⁵ platelets/mL. Similar cardioprotec tion 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.

Key Words: platelets • ischemia-reperfusion • heart.

Journal of Cardiovascular Pharmacology and Therapeutics, Vol. 3, No. 1, 23-28 (1998)
DOI: 10.1177/107424849800300103


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