title: Electroacupuncture most effectively elicits depressor and bradycardic responses at 1 Hz in humans.
abstract: OBJECTIVE
  Acupuncture stimulation is known to act on the autonomic nervous system and elicits depressor and bradycardic effects. However, previous studies on humans did not conduct quantitative analyses on optimal acupuncture conditions such as the stimulation frequency and duration to achieve maximum depressor and bradycardic effects. The aim of the present study was to investigate the effects of varying stimulation frequencies of electroacupuncture on time-dependent changes in blood pressure and heart rate in humans.
  
  
  METHODS
  Twelve healthy volunteers participated in the study. An acupuncture needle was inserted at the Ximen acupoint (PC4 according to WHO nomenclature), located at the anterior aspect of the forearm. An electrical stimulation was delivered through the acupuncture needle at an intensity of 1 V, pulse width of 5 ms, and stimulation frequencies of 0.5, 1, 5, and 10 Hz in a random order. The duration of electroacupuncture was 6 min, during which blood pressure and heart rate responses were monitored.
  
  
  RESULTS
  Group-averaged data indicated that 1-Hz electroacupuncture decreased blood pressure and heart rate. Blood pressure was significantly decreased from the prestimulation baseline value of 86.6 ± 2.9 to 81.4 ± 2.3 mmHg during 4-6 min of 1-Hz electroacupuncture (mean ± SE, P < 0.01). Heart rate was also significantly decreased (from 66.2 ± 2.0 to 62.7 ± 1.7 beats/min, P < 0.01).
  
  
  CONCLUSIONS
  These results provide fundamental evidence that bradycardiac and depressor responses are effectively produced by electrical acupuncture in humans.
authors.affiliation: Graduate School of Health Sciences, Morinomiya University of Medical Sciences, 1-26-16 Nankokita, Suminoe, Osaka, Osaka, 559-8611, Japan. nakahara@morinomiya-u.ac.jp.
authors.forename: Hidehiro
authors.initials: H
authors.lastname: Nakahara
authors.affiliation: Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, 5-7-1 Fujishirodai, Suita, Osaka, 565-8565, Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Kawada
authors.affiliation: Graduate School of Health Sciences, Morinomiya University of Medical Sciences, 1-26-16 Nankokita, Suminoe, Osaka, Osaka, 559-8611, Japan.
authors.forename: Shin-ya
authors.initials: SY
authors.lastname: Ueda
authors.affiliation: Graduate School of Health Sciences, Morinomiya University of Medical Sciences, 1-26-16 Nankokita, Suminoe, Osaka, Osaka, 559-8611, Japan.
authors.forename: Eriko
authors.initials: E
authors.lastname: Kawai
authors.affiliation: Division of Cardiology, Department of Medicine, Faculty of Medicine, Kinki University, 377-2 Ohno-higashi, Sayama, Osaka, 589-8511, Japan.
authors.forename: Hiromi
authors.initials: H
authors.lastname: Yamamoto
authors.affiliation: Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, 5-7-1 Fujishirodai, Suita, Osaka, 565-8565, Japan.
authors.forename: Masaru
authors.initials: M
authors.lastname: Sugimachi
authors.affiliation: Graduate School of Health Sciences, Morinomiya University of Medical Sciences, 1-26-16 Nankokita, Suminoe, Osaka, Osaka, 559-8611, Japan.
authors.forename: Tadayoshi
authors.initials: T
authors.lastname: Miyamoto
mesh_terms: D001341:Autonomic Nervous System / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology*; D001919:Bradycardia / Q000503:physiopathology; D015671:Electroacupuncture / Q000379:methods*; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D055815:Young Adult
keywords: Blood pressure; Electroacupuncture; Heart rate; Stimulation frequencies