THE ROLES OF ACTIVATED LEUKOCYTES, NITRIC OXIDE AND PEROXYNITRITE IN MYOCARDIAL REPERFUSION INJURY

Sedat ALTUG*°, A. Tuncay DEMIRYÜREK*, Ilker KANZIK*

*Gazi University, Faculty of Pharmacy, Department of Pharmacognosy, 06330 Etiler, Ankara, TURKEY.
°Corresponding Author

Summary:
Reperfusion is the only way to solvage the ischaemic myocardium. Worsening of contractility, irreversible arrhythmias such as ventricular fibrillation and tissue injury make reperfusion hazardous. In in vivo conditions, leukocytes play an important role in reperfusion injury. Attenuation of the infiltration and adhesion of leukocytes to the reperfused area by nitric oxide (NO) and peroxynitrite (ONOO-) improves protection, although this does not appear to be the main source of protection. In addition to its coronary vasodilator effect, inhibition of platelet aggregation and adhesion, negative inotropic, chronotropic and positive lusitrophic effects may play an important roles in the cardioprotection produced by NO. The balance between nitric oxide and superoxide is very important in reperfusion injury. If this balance is in favour of NO, leukocyte adhesion is prevented. However, if this balance moves towards an increase in superoxide concentration, reperfusion injury is aggravated. Currently the mechanism of protection by peroxynitrite in micromolar concentration is not completely known and further studies are needed in order to understand the mechanism. Determination of the exact role of ONOO- in reperfusion injury and its relation to poly (ADP-ribose) synthase (PARS) activation will lead to a novel approach to the therapy of myocardial infarction.

Key words:
Ischaemia-reperfusion, Leukocyte, Nitric oxide, Peroxynitrite.