The findings of this study are at odds with studies that show acupuncture at PC6 causes parasympathetic enhancement, not sympathetic enhancement. So not exactly sure what to make of this one. Only the abstract is available unfortunately, since I would be interested to see exactly how they measured the HRV. Also, using healthy volunteers may make the findings harder to interpret.
Europace. 2013 Jan;15(1):127-34. doi: 10.1093/europace/eus220.
Electroacupuncture improves orthostatic tolerance in healthy individuals via improving cardiac function and activating the sympathetic system.
Sun J, Sang H, Yang C, Dong H, et al…
Department of Anesthesiology, Xijing Hospital, Fourth Military Medical University, Xi’an, Shaanxi, China.
Orthostatic intolerance (OI) is a common clinical problem; however, effective and applicable clinical prevention/treatment is limited. The aim of this study was to investigate whether electroacupuncture (EA) is a novel effective treatment in attenuating OI in healthy individuals.
METHODS AND RESULTS:
This study used a randomized, controlled, crossover design using two protocols. Orthostatic intolerance was induced with a combination of head-up tilt (HUT) and lower body negative pressure (LBNP). Twenty healthy individuals in Protocol 1 and 10 healthy individuals in Protocol 2 received no EA, EA at PC-6 acupuncture points (acupoint), and EA at a non-acupoint in a random order with an interim of 1 week. Electroacupuncture was administered prior to HUT/LBNP in Protocol 1 and simultaneously during HUT/LBNP in Protocol 2. Electroacupuncture at PC-6 administered either before or during HUT/LBNP postponed the occurrence of pre-syncopal symptoms, improved haemodynamic responses to HUT/LBNP (including increased diastolic blood pressure, stroke volume, and total peripheral resistance and a decreased heart rate), blunted decreases of maximum velocity and velocity time integral of blood flow in the middle cerebral artery, and increased plasma noradrenalin and adrenalin concentrations. In addition, heart rate variability analysis revealed that EA at PC-6 either before or during HUT/LBNP decreased high-frequency ranges of R-R interval while increasing low-frequency ranges of R-R interval, which indicates an elevated heart sympathetic tone.
Electroacupuncture at PC-6 is effective in improving orthostatic tolerance. Cardiac function improvement and sympathetic activation are responsible for the improved orthostatic tolerance after EA. EA represents a novel intervention against OI.