Chronic whole body sympathectomy fails to protect ischemic rabbit hearts

We determined whether chronic chemical sympathetic denervation could protect the rabbit heart against ischemia. Rabbits received 10 mg/kg 6-hydroxydopamine (6-HD) twice during the first week, then 100 mg.kg-1.wk-1 for the following 7 wk. After this interval the rabbits were anesthetized, the chests were opened, and in each a coronary branch was occluded for 45 min followed by reperfusion for 3 h. Collateral flow was determined with radioactive microspheres during coronary occlusion. Flow to the ischemic myocardium of the 6-HD group (0.06 +/- 0.03 ml.min-1.g-1) was not significantly different from that in the control group (0.04 +/- 0.02 ml.min-1.g-1). Infarct size was determined with triphenyltetrazolium chloride staining. Average infarct size calculated as a percentage of risk zone was similar in the 6-HD and control groups (59 +/- 15 and 60 +/- 12%, respectively). We conclude that chronic chemical sympathectomy does not induce collateral growth in the rabbit heart. Furthermore, endogenous catecholamines do not contribute to injury in the ischemic rabbit heart.