Objectiveβ-blockers (BBs) with different pharmacological properties may have heterogeneous effects on sympathetic nervous activity (SNA) and central aortic pressure (CAP), which are independent cardiovascular factors for hypertension. Hence, we analyzed the effects of bisoprolol and atenolol on SNA and CAP in hypertensive patients.MethodsThis was a prospective, randomized, controlled study in 109 never-treated hypertensive subjects randomized to bisoprolol (5 mg) or atenolol (50 mg) for 4–8 weeks. SNA, baroreflex sensitivity (BRS) and heart rate (HR) variability (HRV) were measured using power spectral analysis using a Finometer. CAP and related parameters were determined using the SphygmoCor device (pulse wave analysis).ResultsBoth drugs were similarly effective in reducing brachial BP. However, central systolic BP (−14±10 mm Hg vs −6±9 mm Hg; P<0.001) and aortic pulse pressure (−3±10 mm Hg vs +3±8 mm Hg; P<0.001) decreased more significantly with bisoprolol than with atenolol. The augmentation index at a HR of 75 bpm (AIxatHR75) was significantly decreased (29%±11% to 25%±12%; P = 0.026) in the bisoprolol group only. Furthermore, the change in BRS in the bisoprolol group (3.99±4.19 ms/mmHg) was higher than in the atenolol group (2.66±3.78 ms/mmHg), although not statistically significant (P>0.05). BRS was stable when RHR was controlled (RHR≤65 bpm), and the two treatments had similar effects on the low frequency/high frequency (HF) ratio and on HF.ConclusionBBs seem to have different effects on arterial distensibility and compliance in hypertensive subjects. Compared with atenolol, bisoprolol may have a better effect on CAP.Trial RegistrationClinicalTrials.gov NCT01762436
On the basis of a two-fluid, cold-plasma, linear stability calculation
with linear friction between electrons and ions, the growth rate of
Alfvén waves is derived
from the dispersion relation for a uniformly magnetized plasma, in which
the
plasma resistivity and a uniform electric current carried by an electron
beam
are both considered. The growth rate is directly proportional to the plasma
resistivity, the electric current density and the value of the parameter
ωxpe/Ωe
(where ωxpe and Ωe
are the
electron plasma and cyclotron frequency respectively).
Moreover, the growth of Alfvén waves is mainly excited in a direction
nearly
parallel to the ambient magnetic field. The critical value of the velocity
of the
electron fluid is just equal to the Alfvén velocity. The results
of this paper are compared with those for the linear tearing mode.
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