The selective alpha-adrenergic receptor agonist dexmedetomidine (DEX) does not affect aortic pressure augmentation

Abstract

Background Despite a similar reduction in peripheral blood pressure (BP), antihypertensive drugs have variable effects on central blood pressure and its augmentation by the reflected pulse wave, a measure of arterial stiffness. Infusion of norepinephrine (NE) increases arterial stiffness. Centrally acting alpha2-AR agonists decrease NE concentrations and blood pressure, but their effects on aortic pressure augmentation are not known. Methods In a single-blind, placebo-controlled study, 36 healthy subjects received sequential infusions of placebo and DEX (0.1, 0.15 and 0.15 mcg/kg). Brachial artery blood pressure, heart rate, and NE plasma concentrations were measured at baseline and after every infusion. Radial artery waveforms were recorded by applanation tonometry (Sphygmocor) and the central aortic waveform and augmentation index - the proportional increase in systolic pressure due to the reflected wave - calculated. Results DEX reduced brachial and central systolic (−15.0±6.2 (SD) and −12.6±5.8 mmHg) and diastolic BP (−9.9±6.5 and −10.1±6.6 mmHg), respectively (p<0.001). NE levels decreased (−103±68 pg/mL, p<0.001) but augmentation index did not change (placebo 3.4±10.3% vs DEX 3.0±10.1%, P=0.8). Conclusion DEX reduced NE concentrations and central and peripheral blood pressure but did not alter aortic pressure augmentation. Pharmacological reduction of endogenous baseline NE concentrations did not alter arterial stiffness and pulse wave reflection. Clinical Pharmacology & Therapeutics (2005) 77, P11–P11; doi: 10.1016/j.clpt.2004.11.046