Blood Vessels Acute -Adrenergic Blockade Increases Aortic Wave Reflection in Young Men and Women Differing Mechanisms Between Sexes

Acute -adrenergic blockade increases aortic wave reflection; however, the mechanisms remain unclear. Evidence suggests that -adrenergic receptor sensitivity in the peripheral vasculature differs between sexes. Therefore, the goal of this study was to examine whether -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 -blockade (0.25 mg/kg bolus, followed by 0.004 mg/kg per minute of continuous infusion of propranolol). -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 -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 -blockade, and enhanced aortic wave reflection appears to be mediated by a reduced heart rate in men, whereas the mechanism is unclear in women. (Hypertension. 2012;59:145-150.)