OBJECTIVETo explore the protective effect and the mechanism of controlled hypotension induced by transcutaneous electrical acupoint stimulation (TEAS) combined with general anesthesia.

METHODSSixteen male Beagles were randomly divided into a group of controlled hypotension induced by simple general anesthesia (control group) and a group of controlled hypotension induced by TEAS combined with general anesthesia (observation group). All the animals were administered with combination of Isoflurane and Sodium Nitroprusside (SNP) for controlled hypotension without TEAS until the arterial pressure was lowered to 30% basic mean arterial pressure (MAP) for 60 min. In the observation group, TEAS (2 Hz/100 Hz, 3-5 mA) was applied to "Hegu" (LI 4) "Zusanli" (ST 36), "Sanyinjiao" (SP 6) and "Quchi" (LI 11) from the beginning of physiological conditions stability to the end of maintained low MAP for 60 min, but there was no TEAS in control group. The changes of MAP, the left intraventricular pressure (LIVP), T wave and ST-T segment of II lead electrocardiogram (ECG) were monitored with the physiological signal acquisition system, and myocardial apoptosis was detected by TUNEL method.

RESULTSAll the animals could maintain stable required low blood pressure. At one hour after cease of controlled hypotension, MAP of (109.56 +/- 6.14) mmHg returned to the basic level in the observation group, while MAP of (84.91 +/- 6.36) mmHg was still lower than its basic MAP of (111.02 +/- 4.15) mmHg in the control group (P < 0.05), showing significant difference in MAP between the two groups (P < 0.05). -dp/dtmax of (3156.32 +/- 332.82) mmHg/s showed significant lower than its basic value of (4585.33 +/- 638.55) mmHg/s when blood pressure increased for 1 h in the control group (P < 0.05), but there was no difference in the observation group. When the objective low MAP maintaining for 60 min the ST segment was decreased significantly in the control group (P < 0.05), but there was no difference in the observation group. The numbers of positive apoptosis cardiocytes in the observation group were (24.67 +/- 2.45) cells/mm2, which were significantly fewer than (37.89 +/- 1.90) cells/mm2 in the control group (P < 0. 05).

CONCLUSIONSTEAS combined with general anesthesia for controlled hypotension can significantly shorten restoration time of MAP, help to improve myocardial ischemia and the cardiac functional recovery and reduce myocardial apoptosis so as to produce myocardial protection.