title: Relation between actual heart rate and autonomic effects of beta blockade in healthy men.
abstract: This study evaluated the effect of beta blockade on cardiac autonomic control and its dependence on heart rate change. The relations between RR interval duration, heart rate variability (HRV), and baroreflex sensitivity (BRS) were studied in 111 healthy men and in 21 male volunteers before and after a 100-mg oral dose of metoprolol. HRV and BRS correlated significantly with mean RR (r = 0.39, r = 0.57). Metoprolol administration increased both mean RR (from 996 to 1,176 ms, p <0.001), BRS from 24 to 36 ms/mm Hg (p = 0.003), and the SD of RR from 61 to 74 ms (p = 0.05). However, metoprolol-induced changes of HRV and BRS became insignificant (p = 0.69 and 0.48) after they were normalized to the same cycle length, suggesting that the improvement of cardiac autonomic control after beta blockade could be explained by a change of heart rate.
authors.affiliation: Third Department of Internal Medicine, First School of Medicine, Charles University, Prague, Czech Republic. vmeleno2@jhmi.edu <vmeleno2@jhmi.edu>
authors.forename: Vojtech
authors.initials: V
authors.lastname: Melenovsky
authors.forename: Jan
authors.initials: J
authors.lastname: Simek
authors.forename: Michal
authors.initials: M
authors.lastname: Sperl
authors.forename: Jan
authors.initials: J
authors.lastname: Malik
authors.forename: Dan
authors.initials: D
authors.lastname: Wichterle
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000328:Adult; D001341:Autonomic Nervous System / Q000187:drug effects / Q000502:physiology; D017704:Baroreflex; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D008297:Male
chemical_list: D000319:Adrenergic beta-Antagonists