The antiarrhythmic effect of exogenous peroxynitrite and preconditioning: the involvement of nitric oxide, superoxide and peroxynitrite

Abstract

Full papersIWe showed, that compared to the controls, two 5 min periods of the 100 nM concentration of PN, similar to the same periods of preconditioning ischaemia, markedly reduced the severity of arrhythmias and attenuated the generation of NT that resulted from a 25 min occlusion and reperfusion of the left anterior descending coronary artery. Since these effects were not modified by the prior administration of 5-HD, we concluded that, in contrast to PC, the antiarrhythmic effect of PN does not involve the opening of mitoK ATP channels.However, the observed attenuation in I/R-induced NT formation following PC and PN has promted us to examine, whether this results from a reduced NO or from a reduced O 2 . production. Therefore, in another series of experiments we measured changes in plasma and tissue nitrate/nitrite (NOx, a biomarker of NO production), O 2 . and NT productions in control, in PC and in PN treated dogs. We have found that in contrast to the controls in which the plasma NOx levels were markedly decreased by the end of the occlusion, in dogs subjected to PC and PN infusion NOx levels were maintained over the entire ischaemic period.