Clinical Research
Clinical Research Papers
Adrenergic ß - Blockade with Intrinsic Sympathomimetric Activity May Attenuate Improvement in
Vascular Compliance During Exercise
CP Liu, TJ Brinton*, ED Walls*, SL Lin,
SS Chio, HT Chiang. Veterans General Hospital-Kaohsiung, Taiwan,
ROC and Pulse Metric, Inc., San Diego, CA, USA.
Intrinsic
sympathomimetric activity (ISA) may balance the negative
inotropic and chronotropic effects of ß
-blocker therapy theoretically. However, the effect of adrenergic
ß -blockade with ISA on vascular
compliance C is still not thoroughly known. We measured mean
arterial pressure (MAP), HR, maximum left ventricle dP/dt (dP/dtLVmax),
and C utilizing cuff sphygmomanometer waveform analysis in 28
hypertensive patients who received either propranol (group A, n =
16) or acebutolol (group B, n = 12). C was assessed during rest
and submaximal exercise. Results mean ±
SD (*p<0.05)
| |
Wk |
MAP |
HR |
dP/dtLVmax |
C (ml/mmHg) |
| |
|
(mmHg) |
(bpm) |
(mmHg/sec) |
Resting |
Exercise % |
| A |
0 |
116.9±
11 |
74.4±
13 |
1369±
221 |
0.087±
0.026 |
-12.6±
8% |
| |
8 |
103.1±
12* |
61.1±
7* |
1189±
251* |
0.092±
0.023 |
+8.7±
12% |
| B |
0 |
126.9±
12 |
75.4±
13 |
1399±
171 |
0.084±
0.013 |
-8.3±
9% |
| |
8 |
111.8±
11* |
64.9±
7* |
1205±
226* |
0.088±
0.025 |
+3.4±
8% |
Following 8 weeks therapy, the improvement in blood pressure
and C was similar in both groups. However, the reduction in HR in
group B was less than group A. Although the response of C to
exercise in both groups was not different, the net increase in C
after therapy is significantly larger in group A than in group B
(21.3± 7.6% vs. 11.7± 8.9%, p<0.05). These results suggest
that acebutolol, a ß -blocker with
ISA, may attenuate propranolol induced improvement in vascular
compliance during exercise in hypertensive patients.
Key Words: Intrinsic Sympathomimetic Activity, Vascular
Compliance
|
