Recently, we have shown that rat hearts subjected to global ischemia generate nitric oxide (NO), a significant portion of which is not blocked by nitric oxide synthase inhibitors suggesting the existence of an enzymeindependent pathway of NO generation. We have shown that this pathway of NO generation involves direct reduction of nitrite under the acidic and reducing conditions that occur during myocardial ischemia [Nature Medicine, 1, 804-809 (1995)]. In view of the important implications of this enzymeindependent mechanism of NO generation on the pathogenesis and treatment of tissue injury, we have further attempted to map the spatial distributions of NO generated in ischémie myocardium using L-band electron paramagnetic resonance imaging. Rat hearts were loaded with 10 mM nitrite and subjected to global no-flow ischemia, during which time a series of three dimensional spatial EPR images of the distribution of NO were obtained using the NO trap Fe-MGD. The images clearly showed that NO is formed throughout the myocardium enabling visualization of the external shape of the epicardium, right ventricular (RV) myocardium and internal endocardial surface of the left ventricle (LV) and LV chamber. Kinetic experiments show that maximum NO generation and trapping occurred at the midmyocardium and spreads out to endocardium and epicardium of the LV. The magnitude of generation in the RV myocardium was 4-5 fold lower than in the LV.
|Published - 1996
ASJC Scopus subject areas
- Agricultural and Biological Sciences (miscellaneous)
- Biochemistry, Genetics and Molecular Biology(all)
- Cell Biology