Electracupuncture Could Ameliorate Orthostatic Intolerance After Weightlessness by Improving Cardiovascular Function

Spaceflight is associated with cardiovascular deregulation. However, the influence of microgravity on the cardiovascular system and the underlying mechanisms and countermeasures remain largely unknown. Our previous studies have demonstrated that electroacupuncture (EA) is effective at improving orthostatic tolerance (OT). The purpose of this study was to determine if EA treatment can attenuate cardiovascular deconditioning induced by a 4-day -6° head-down bed rest (HDBR). Fourteen healthy male subjects were randomly allocated into a control group (Con, n=6, 4 days HDBR without countermeasure) and an EA treatment group (EA, n=8, 4 days HDBR with EA at Neiguan [PC-6] for 30 min daily for 4 consecutive days during HDBR). OT was estimated with a combination of +75°/20 min head-up tilt and lower body negative pressure test before and after HDBR. Plasma hormones and heart rate variability were assessed before and after HDBR. Cardiac systolic functions and cerebral blood flow were measured before, during, and after HDBR. The data showed that EA treatment applied daily for 30 min during a 4-day HDBR prevented OT and cardiac systolic function from decrease, prevented autonomic dysfunction (a decrease in the activity of the parasympathetic nervous system), and increased the concentrations of plasma angiotensin II (Ang II) and aldosterone (Ald). These results indicate that 30 min of daily EA treatment at PC-6 is highly effective in partially maintaining OT and cardiac systolic function. Activation of the peripheral sympathetic nervous system and increased plasma hormones is largely responsible for maintaining OT after a 4-day HDBR. Therefore, EA treatment appears to be an effective countermeasure against cardiovascular deconditioning induced by HDBR.