Effects of right stellate ganglion stimulation on regional myocardial blood flow and ischemic injury in dogs.

The effects of right stellate ganglion stimulation (RSGS) on regional myocardial blood flow (RMBF) and epicardial ST-segment elevation were investigated in the normal and ischemic myocardium of anesthetized dogs. In the non-ischemic areas and despite the augmentation of cardiac work resulting from the increase in heart rate and in myocardial contractile force, RSGS induced no significant changes in RMBF or in the endo/epi ratio. However, after suppression by atenolol of its chronotropic and inotropic effects, RSGS significantly increased the calculated coronary resistance and reduced RMBF, and combined atenolol + phenoxybenzamine treatments abolished these effects. In the ischemic areas, RSGS had no effect on RMBF, endo/epi and I/NI ratios but increased ST-segment elevation, an effect abolished by atenolol. We conclude that (1) during RSGS, alpha-adrenoreceptor-mediated coronary vasoconstriction contributes to oppose beta 1-myocardial stimulation effects on RMBF and endo/epi ratio, (2) further elevation of ST-segment by RSGS is due to enhancement of oxygen requirements by beta 1-adrenoreceptor stimulation.