title: Assessment of autonomic function in humans by heart rate spectral analysis.
abstract: Spectral analysis of spontaneous heart rate fluctuations were assessed by use of autonomic blocking agents and changes in posture. Low-frequency fluctuations (below 0.12 Hz) in the supine position are mediated entirely by the parasympathetic nervous system. On standing, the low-frequency fluctuations increase and are jointly mediated by the sympathetic and parasympathetic nervous systems. High-frequency fluctuations, at the respiratory frequency, are decreased by standing and are mediated solely by the parasympathetic system. Heart rate spectral analysis is a powerful noninvasive tool for quantifying autonomic nervous system activity.
mesh_terms: D000328:Adult; D001285:Atropine / Q000494:pharmacology; D001340:Autonomic Nerve Block; D001341:Autonomic Nervous System / Q000502:physiology*; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D011187:Posture; D011433:Propranolol / Q000494:pharmacology; D013057:Spectrum Analysis / Q000379:methods
chemical_list: D001285:Atropine; D011433:Propranolol