Effects of acute beta-adrenergic receptor blockade on age-associated changes in cardiovascular performance during dynamic exercise.

• DOI: 10.1161/01.cir.90.5.2333
• Publication Date: 2012-06-12T00:34:42Z
• Authors: J L Fleg; S Schulman; F O'Connor; L C Becker; G Gerstenblith; J F Clulow; D G Renlund; E G Lakatta
• Keywords: Cardiac index

The cardiovascular response to beta-adrenergic stimulation is markedly blunted with advancing age, and this blunting may underlie some of the prominent age-associated changes in hemodynamic profile during dynamic exercise. To examine hypothesis, we administered nonselective receptor blocker propranolol (0.15 mg/kg IV) 25 healthy normotensive men ages 28 72 years from Baltimore Longitudinal Study Aging (BLSA) immediately before maximal upright cycle ergometry 99mTc gated cardiac blood pool scintigraphy. Their responses exercise were compared those 70 age-matched unmedicated male BLSA control subjects. work rate achieved was similar propranolol-treated (158 +/- 32 W) subjects (148 declined similarly age both groups. Hemodynamics at seated rest not age-related either group; however, had lower heart rates (HR), systolic pressure (SBP), ejection fraction, index than but higher end-diastolic volume (EDVI) end-systolic (ESVI) by covariance analysis. At effort, several striking age-drug interactions evident: Propranolol caused a greater reduction HR increases EDVI stroke (SVI) younger older men. Hence, rate, less group (0.46 versus 1.09 beats per minute year, P < .05 analysis); SVI decreased (0.27 0.48 mL/m2 respectively) after 0.47 0.16 year subjects, respectively, each or = left ventricular contractility index, SBP/ESVI, exhaustion reduced extent Thus, acute blockade reverses dilation end diastole systole observed blunts decline myocardial contractility. These data suggest that declines vigorous are manifestations responsivity which partially offset exercise-induced dilation.