Variations in energy metabolism along the pericardium meridian and its relationship with visceral function adjustments during electroacupuncture

BACKGROUND: Electroacupuncture (EA) is a traditional Chinese medicine treatment guided by meridian theory. As it gradually gains more worldwide acceptance, a clarification of its mechanisms is extremely urgent. We observed variations in transcutaneous oxygen pressure/carbon dioxide pressure ((tcp)O(2)/(tcp)CO(2)) and microcirculation blood perfusion units (BPU) along the pericardium meridian, and cardiac function during EA at Neiguan (PC6) to explore variations in energy metabolism and its relationship with visceral function adjustments during EA. METHODS: Twenty-two healthy volunteers participated in this study. Three channel laser Doppler flowmetry and (tcp)O(2)/(tcp)CO(2) detection systems were used to detect (tcp)O(2)/(tcp)CO(2) and microcirculation BPU along the pericardium meridian. A hemodynamic monitor was used to detect cardiac function. RESULTS: In the normal state, the microcirculatory BPU along the pericardium meridian were significantly higher than that of their bilateral corresponding control points (p < 0.05). During EA at PC6, the values of the microcirculatory BPU along the pericardium meridian did not vary, and few increased. In the normal state, the values of (tcp)O(2) along the pericardium meridian were significantly higher than those of their bilateral corresponding control points (p < 0.05). In addition, the values of (tcp)CO(2) along the pericardium meridian were lower than those of their bilateral corresponding control points. In comparison with the normal state, EA could decrease (tcp)O(2) along the meridian significantly (p < 0.05) and increase (tcp)CO(2). During EA at PC6 in healthy volunteers treated by artificial acute mild hypoxia, cardiac output and cardiac index (p < 0.05) decreased and systemic vascular resistance increased significantly (p < 0.05). CONCLUSIONS: In the normal state, the values of microcirculatory BPU and (tcp)O(2) along the pericardium meridian were both higher than those of their bilateral corresponding control points. Energy metabolism was vigorous along the meridian. During EA, the decrease in oxygen partial pressure along the pericardium meridian might be a result of strengthened energy metabolism of associated tissue and increased oxygen consumption. The variations in energy metabolism along the pericardium meridian during the course of EA had a close relationship with visceral function adjustments. TRIAL REGISTRATION: Chinese Clinical Trial Registry ChiCTRTRC13003193.