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Effect of 4 weeks of amlodipine therapy on muscle
sympathetic nerve activity
12th Annual ASH Meeting
Am J Hypertens
(Apr) 10:24A 1997
This study was designed to determine the effects short-term amlodipine
therapy on muscle sympathetic nerve activity (MSNA). Previously , using
venous NE levels in other studies gave opposite results. Thus,
Messerli et
al, observed an increase in plasma norepinephrine levels and heart
rate with
long-term dihydropyridine treatment in 1252 hypertensive patients.
The methods used in the present study were the recording of MSNA by
microneurography of the left peroneal nerve. A small group of 10 subjects
(5 whites and 5 African Americans) were studied once before treatment,
after 4 weeks of amlodipine 5 mg/day, and (as stated in the presentation),
after 3 months of treatment.
Findings showed that systolic, diastolic, and mean BP were reduced
significantly by the calcium blocker, while the heart rate was not changed
during treatment. On the other hand, evaluation of MSNA by
microneurography indicated the SNS was in fact activated (from 35 4.8 to
49 3.7 bursts/min, p < 0.05. Thus, HR was a poor guideline of SNA. The
study confirms other observations of NE increase in many cases.
Comment: The potential long-term adverse effects of calcium blockers
remain a source of intense controversy. Activation of the SNS while the
BP is reduced may be related to possibly unfavorable long-term outcomes
and allegedly increased mortality. Of interest, the authors have observed
also that ACE inhibitors improve the SNS activation found in the SHR animal
model. This area of research seems worthy of additional effort.
(Armando Lindner, M.D., University of Washington, Seattle)
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12th Annual ASH Meeting
H: Pathophysiology :
Sympathetic nervous system