CONICET | Buscador de Institutos y Recursos Humanos

The aim of this study was to analyze the effects of brief vagal stimulation (VS) applied before ischemia on acute myocardial infarction and its long-term benefits on an experimental ischemia/reperfusion and non-reperfusion model.Male FVB mice were randomly assigned to different groups and a regional myocardial ischemia of the left descendant coronary artery during 45 min, followed by either 2 hours, 28 days of reperfusion or no reperfusion at all, with or without 10 min of pre-ischemic vagal stimulation (VS) was performed. In order to evaluate de participation of muscarinic receptors, atropine was administrated during VS. Left ventricular function (LVF) was assessed by echocardiography and catheterization of the left ventricle via the left carotid artery. Morphometric parameters were also analyzed by a comparison of both ventricles weight (VW) and lungs weight (LW) with the length of the tale (TL) and the tibia (TiL). Finally, infarct size (IS) on the 2h reperfused hearts was measured with TTC. VS+IR-2h presented smaller IS compared to IR-2h and administration of atropine reverted the protection. On the other hand, while the IR-28d group showed a significantly higher LVEDP with a lower EF% and SF% compared to the Sham-28d group, and VS reverted this findings, the administration of atropine did not reduced echocardiographic parameters. In addition to this, a reduction of the FE% and SF% was observed in the non-reperfused group that could be reverted with VS and did not changed with atropine during stimulation. Finally, morphometric results showed in the IR-28d group an increment in the VW compared to TiL and TL which did not descend with VS and similar behavior was found in non-reperfused groups. In conclusion, brief VS applied before ischemia confers cardioprotection, reducing the acute infarct size and improving long-term LVF independently of the action of muscarinic receptor and infarct size.