CARDIAC SYMPATHETIC NERVOUS ACTIVITY DURING MYOCARDIAL-ISCHEMIA, REPERFUSION AND VENTRICULAR-FIBRILLATION IN THE DOG - EFFECTS OF INTRAVENOUS LIDOCAINE

In 12 open-chest dogs, cardiac sympathetic nervous activity (CSNA) was recorded before and after occlusion of the left anterior descending coronary artery as well as during reperfusion and ventricular fibrillation (VF). In 7 control animals, CSNA did not significantly differ from preocclusion levels when determined 20 min after occlusion (+3.5 +/- 1.5 %, mean +/- SEM) and up to 15 min following reperfusion (+1.5 +/- 0.06%). However, VF was associated with a potential increase in CSNA by 106 +/- 1 5.5% (p < 0.001). The effect of lidocaine (6 mg/kg) on cardiac sympathetic tone was examined in 5 additional animals. Lidocaine reduced control CSNA by 23 +/- 4.7% (p < 0.001); subsequent ischemia and reperfusion did not substantially change the level of preocclusion activity. CSNA decreased significantly also during VF (52 +/- 4.2%, p < 0.00 1). In conclusion, efferent CSNA was slightly altered in the course of acute myocardial ischemia and reperfusion, but significantly increased during VF. Lidocaine produced marked attenuation of CSNA in anesthetized dogs.