Li P, Pitsillides K F, Rendig S V, Pan H L, Longhurst J C
Department of Physiology, Shanghai Medical University, China.
Circulation. 1998 Mar 31;97(12):1186-94. doi: 10.1161/01.cir.97.12.1186.
Acupuncture is reported to reduce myocardial ischemia, arrhythmias, and hypertension. To investigate the physiological mechanisms underlying these observations, a model of reflex-induced, reversible myocardial ischemia was developed to test the effects of median nerve stimulation as a surrogate for electroacupuncture.
Chloralose-anesthetized cats were instrumented to measure arterial blood pressure, left ventricular pressure, left ventricular dP/dt, heart rate, left anterior descending (LAD) coronary blood velocity, and regional wall motion. The LAD artery either was partially occluded or a small diagonal branch was ligated. Subsequently, transient reflex activation of the cardiovascular system was evoked by application of bradykinin (typically 1 microg/mL) to the gallbladder, which significantly increased myocardial oxygen demand (double product), left ventricular dP/dt, and coronary blood velocity and caused ischemia-induced regional dysfunction, evidenced by significant (P<.05) reduction in normalized wall thickening (10.7+/-4.2% versus -23.6+/-2.9%; control versus ischemia; n=7). However, when median nerves were stimulated with low frequency (5 Hz) to mimic electroacupuncture, bradykinin-induced change in normalized wall thickening was significantly improved (-23.6+/-2.9% versus 9.8+/-4.9%; ischemia versus median nerve stimulation, P<.05) and remained augmented > or = 1 hour. Results were similar in partial and complete occlusion groups. Significant improvement in wall thickening was associated with unchanged increment of coronary blood velocity and significantly diminished increments of double product and diastolic blood pressure.
These results suggest that stimulation of the median nerve to mimic electroacupuncture diminishes regional myocardial ischemia triggered by a sympathetically mediated increase in cardiac oxygen demand. The mechanism of this effect is related to reduction in cardiac oxygen demand, secondary to a diminished pressor response. These data provide the first documentation of the physiological mechanisms underlying the possible beneficial effect of electroacupuncture in the context of restricted coronary blood flow and augmented myocardial oxygen demand.
据报道，针灸可减轻心肌缺血、心律失常和高血压。为了研究这些观察结果背后的生理机制，建立了一种反射性诱导的可逆性心肌缺血模型，以测试正中神经刺激作为电针替代方法的效果。
用氯醛糖麻醉猫，监测动脉血压、左心室压力、左心室dp/dt、心率、左前降支（LAD）冠状动脉血流速度和局部室壁运动。LAD动脉要么部分闭塞，要么结扎一小对角支。随后，通过向胆囊内注入缓激肽（通常为1μg/mL）诱发心血管系统的短暂反射激活，这显著增加了心肌需氧量（双乘积）、左心室dp/dt和冠状动脉血流速度，并导致缺血性局部功能障碍，表现为标准化室壁增厚显著降低（对照组为10.7±4.2%，缺血组为-23.6±2.9%；P<0.05；n=7）。然而，当以低频（5Hz）刺激正中神经以模拟电针时，缓激肽诱导的标准化室壁增厚变化得到显著改善（缺血组为-23.6±2.9%，正中神经刺激组为9.8±4.9%；P<0.05），且在≥1小时内持续增强。部分闭塞组和完全闭塞组的结果相似。室壁增厚的显著改善与冠状动脉血流速度的增量不变以及双乘积和舒张压的增量显著减小有关。
这些结果表明，刺激正中神经以模拟电针可减轻因交感神经介导的心脏需氧量增加而引发的局部心肌缺血。这种效应的机制与压力反应减弱继发的心脏需氧量减少有关。这些数据首次记录了在冠状动脉血流受限和心肌需氧量增加的情况下，电针可能产生有益作用的生理机制。
