RESUMO
<p><b>OBJECTIVE</b>To explore the mechanism of electroacupuncture at "Neiguan" (PC 6) antagonizing myocardial ischemia injury.</p><p><b>METHODS</b>Forty rabbits were randomly divided into 4 groups, model control group, naloxone control group, electroacupuncture plus cerebral spinal fluid group, and electroacupuncture plus naloxone group, 10 rabbits in each group. The effects of electroacupuncture at "Neiguan" (PC 6) after injection of naloxone into the paraventricular nucleus (PVN) of the hypothalamus on myocardial ultrastructure, II lead ECG and transmembrane potentials of the ischemic myocardial cell in the rabbit of myocardial ischemia were investigated.</p><p><b>RESULTS</b>The injection of naloxone into PVN has no effect on myocardial functions in the normal rabbit and a little effect on ischemic myocardial functions, but at 60 min after myocardial ischemia, this has a certain protective action on myocardial functions (P < 0.05); electroacupuncture at "Neiguan" has obvious protective action on ischemic myocardium, which can be reduced by injection of naloxone into PVN (P < 0.05), but can not be blocked.</p><p><b>CONCLUSION</b>(1) PVN plays an important role in the process of antagonizing myocardial ischemia by electroacupuncture at "Neiguan"; (2) endogenous opioid pepetides in PVN are involved in the acupuncture effect of antagonizing myocardial ischemia; (3) other transmitters in PVN and other nucleus groups in the center also can produce obvious effects in the antagonism to myocardial ischemia by electroacupuncture at "Neiguan".</p>