Differential effects of beta-adrenoreceptor antagonists on central and peripheral blood pressure at rest and during exercise

Abstract

Background: Differential effects of beta-adrenoreceptor antagonists (beta-ARB) on central and peripheral blood pressure may relate to change in heart rate and/or vasodilator tone and thus be exaggerated during exercise.

Aims: To examine acute effects of selective and nonselective beta-ARB on central and peripheral blood pressure, cardiac output and peripheral vascular resistance during exercise.

Methods: Healthy volunteers (n= 20, 18 men, 19-54 years) received propranolol 80 mg, bisoprolol 20 mg, and placebo 1 h before bicycle ergometry (50, 75 and 100 W each for 3 min) in a randomized, cross-over study. Cardiac output was determined by pulmonary uptake of soluble and inert gas tracers (InnoCor, Innovision). Central systolic blood pressure (SBP) was determined from the late systolic shoulder of the digital artery pressure waveform (Finometer, Finopres).

Results: At rest, both beta-ARB reduced brachial but not central SBP (compared with placebo). During exercise, beta-ARB reduced brachial SBP (reductions of 19.9 +/- 4.3 mmHg and 23.2 +/- 2.7 mmHg for propranolol and bisoprolol, respectively, at 100 W, each P < 0.0001) but not central SBP. The difference between peripheral and central SBP was reduced, relative to that during placebo, by 21.5 mmHg (95% confidence interval 8.8, 34.1) and 26.4 mmHg (18.1, 34.8) for propranolol and bisoprolol, respectively, at 100 W (each P < 0.01). There was no significant effect of beta-ARB on diastolic blood pressure or peripheral vascular resistance.

Conclusions: Despite reducing brachial blood pressure, acute beta-adrenoreceptor blockade in man at rest and during exercise does not reduce central blood pressure.

Figure 1

Cardiac output (CO), heart rate (HR), brachial blood pressure (BP, systolic, mean and diastolic), central systolic blood pressure (cSBP), stroke volume (SV) and systemic vascular resistance (SVR) at rest, during exercise and during recovery after placebo (•, solid line), propranolol (▪, dotted line) and bisoprolol (▴, dashed line). *Propranolol and bisoprolol significantly different from placebo, P < 0.05. **Propranolol and bisoprolol significantly different from placebo, P < 0.01

Figure 2

Relationship between the difference between brachial and central systolic blood pressure (bSBP–cSBP) and heart rate during rest and exercise for the three treatment groups (○: placebo; ▪: propranolol; ▴: bispoprolol). The solid line is the regression line for placebo (R= 0.46, P < 0.001) and the dotted line that for the combined β-blocker groups (R= 0.12, P= NS)