Assessment of parasympathetic control of heart rate by a noninvasive method.
The degree of parasympathetic control of heart rate was assessed by the abolition of respiratory sinus arrhythmia with atropine. Peak-to-peak variations in heart periods (VHP) before atropine injection correlated significantly (r = 0.90, P less than 0.001) with parasympathetic control, indicating that VHP alone may be used as a noninvasive indicator of the parasympathetic control of heart rate. Pharmacologic blockade of beta-adrenergic supply in a separate group of normal volunteers did not alter the relationship between VHP and parasympathetic control, indicating that the condition of the experiment (complete rest in a quiet atmosphere) allows the use of VHP alone without pharmacologic interventions to characterize the vagal control of heart rate in humans.
D000818:Animals; D001285:Atropine; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D006321:Heart / Q000294:innervation*; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D010275:Parasympathetic Nervous System / Q000187:drug effects / Q000502:physiology*; D011433:Propranolol
D001285:Atropine; D011433:Propranolol