title: Acute β-adrenergic blockade increases aortic wave reflection in young men and women: differing mechanisms between sexes.
abstract: Acute β-adrenergic blockade increases aortic wave reflection; however, the mechanisms remain unclear. Evidence suggests that β-adrenergic receptor sensitivity in the peripheral vasculature differs between sexes. Therefore, the goal of this study was to examine whether β-adrenergic blockade alters aortic wave reflection to a similar extent in young men and women. In 31 subjects (16 men and 15 women; 26±1 years) noninvasive aortic pressure waveforms were synthesized from high-fidelity radial pressure waveforms via applanation tonometry before and during systemic β-blockade (0.25 mg/kg bolus, followed by 0.004 mg/kg per minute of continuous infusion of propranolol). β-Blockade increased aortic augmentation index and wave reflection amplitude (aortic augmented pressure) in both sexes (P<0.01). Although the increase in augmentation index was not significantly different between sexes (7.5±1.1% versus 4.6±1.5%; P=0.07), the increase in aortic augmented pressure was greater in women compared with men (2.8±0.5 versus 1.4±0.5 mm Hg; P<0.05). Aortic augmentation index adjusted for a heart rate of 75 bp increased in women (4.1±1.1%; P<0.05) after β-blockade, whereas it was unchanged in men (0.6±1.3%; P=0.33). Moreover, the change in aortic augmentation index was inversely associated with the change in heart rate only in men (r=-0.54; P<0.05). Our data suggest that aortic wave reflection is increased to a greater extent in women after systemic β-blockade, and enhanced aortic wave reflection appears to be mediated by a reduced heart rate in men, whereas the mechanism is unclear in women.
authors: Department of Anesthesiology, Mayo Clinic, 200 First St SW, Rochester, MN 55905, USA. casey.darren@mayo.edu
authors: Darren P
authors: DP
authors: Casey
authors: Timothy B
authors: TB
authors: Curry
authors: Michael J
authors: MJ
authors: Joyner
authors: Nisha
authors: N
authors: Charkoudian
authors: Emma C
authors: EC
authors: Hart
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage*; D000328:Adult; D001011:Aorta / Q000502:physiology*; D001794:Blood Pressure / Q000187:drug effects* / Q000502:physiology; D001916:Brachial Artery / Q000502:physiology; D005260:Female; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D006801:Humans; D008297:Male; D008365:Manometry; D011433:Propranolol / Q000008:administration & dosage*; D011673:Pulsatile Flow / Q000187:drug effects* / Q000502:physiology; D012727:Sex Characteristics
chemical_list: D000319:Adrenergic beta-Antagonists; D011433:Propranolol