MYOCARDIAL EFFECTS OF NITRIC OXIDE AND PEROXYNITRITE SUMMARY

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

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

Summary:
Nitric oxide(NO) is synthesized from L-arginine by NO synthase(NOS) and plays a role in many physiogical and pathological conditions. NOS activity has been shown in the myocardium of human and animals. In the heart, NO is synthesized in coronary, endocardial endothelium and cardiac myocytes. NO reacts rapidly with superoxide radical and forms potent oxidant peroxynitrit (ONOO-). Both an endongenous and an exogenous NO exert negative inotropic and positive lusinotropic effects on myocardium. ONOO- shows a negative inotropic effect on myocardium and causes myocardial injury. Although it is not fully characterized how ONOO- depresses myocardial contractility, it is likely that ONOO- may activate cGMP and\or poly (ADP-ribose) synthase pathway.The control of NO release (selective iNOS inhibition) and development of specific ONOO- scavengers in cardiac pathological conditions,such as ischeamia-reperfusion and myocardial inflammation,will bring new approaches to treatment.

Key words:
Nitric Oxide, Peroxynitrite, Cardiac Contractility.