Acute effects of ephedra on autonomic nervous modulation in healthy young adults.
The aim of this study was to assess the acute effects of ephedra on autonomic nervous modulation by means of heart rate variability (HRV) analysis, using a randomized, double-blind, placebo-controlled, crossover design. On three separate days, 20 healthy subjects took capsules containing either 1 or 2 g of ephedra dry extract or a placebo, and the sequential percentage changes in HRV measures were compared. After the subjects took ephedra, the normalized low-frequency component (LF) and the ratio of LF to high-frequency component (HF) increased significantly in a dose-dependent manner, whereas the normalized HF (HF%) decreased significantly. We conclude that ingestion of ephedra tilts the sympathovagal balance dose-dependently toward increased sympathetic activity and impairs parasympathetic activity.
Institute of Traditional Medicine, National Yang-Ming University, Taipei, Taiwan.
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Chen
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Tsai
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Yang
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Kuo
D000328:Adult; D000465:Algorithms; D001341:Autonomic Nervous System / Q000187:drug effects*; D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004562:Electrocardiography / Q000187:drug effects; D029789:Ephedra / Q000009:adverse effects*; D005260:Female; D005583:Fourier Analysis; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D008297:Male; D055815:Young Adult