Publication:

Effect of 'autonomic blockade' on cardiac beta-adrenergic chronotropic responsiveness in healthy young, healthy elderly and endurance-trained elderly subjects (1994)

Author(s): G. A. Ford;O. F. James

  • : Effect of 'autonomic blockade' on cardiac beta-adrenergic chronotropic responsiveness in healthy young, healthy elderly and endurance-trained elderly subjects

Abstract: 1. Cardiac chronotropic responses to isoprenaline are reduced with ageing in man. It is unclear whether this is due to reduced cardiac beta-adrenergic sensitivity or to age-associated differences in reflex cardiovascular responses to the vasodilatory effects of isoprenaline. Age-associated changes in physical activity are also reported to influence beta-adrenergic sensitivity. 2. The aim of the present study was to determine the contribution of alterations in reflex changes in para-sympathetic and sympathetic influences and physical fitness to the age-associated reduction in cardiac chronotropic responses to beta-adrenergic agonists. 3. The effect of 'autonomic blockade' with atropine (40 micrograms/kg intravenously) and clonidine (4 micrograms/kg intravenously) on blood pressure, heart rate and chronotropic responses to intravenous bolus isoprenaline doses was determined in eight healthy young (mean age 21 years), nine healthy elderly (72 years) and 10 endurance-trained elderly (69 years) subjects. 4. Elderly subjects had a reduced increase in heart rate after atropine (young, 49 +/- 9 beats/min; elderly, 36 +/- 5 beats/min; endurance-trained elderly, 34 +/- 12 beats/min; P < 0.01) and did not demonstrate the transient increase in systolic blood pressure after clonidine observed in young subjects (young, 11 +/- 10 mmHg; elderly, -12 +/- 16 mmHg; endurance-trained elderly, -18 +/- 11 mmHg; P < 0.01). 5. Cardiac chronotropic sensitivity to isoprenaline after 'autonomic blockade' increased in the young but decreased in the elderly subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Notes: 0143-5221 Journal Article

  • Short Title: Effect of 'autonomic blockade' on cardiac beta-adrenergic chronotropic responsiveness in healthy young, healthy elderly and endurance-trained elderly subjects
  • Date: Sep
  • Journal: Clin Sci (Lond)
  • Volume: 87
  • Issue: 3
  • Pages: 297-302
  • Publication type: Article
  • Bibliographic status: Published

Keywords: Adult Age Factors Aged Aged, 80 and over Atropine/*pharmacology Autonomic Nervous System/*drug effects Blood Pressure/drug effects Clonidine/*pharmacology Comparative Study Heart/drug effects Heart Rate/drug effects Hemodynamic Processes/*drug effects Human Isoproterenol/*diagnostic use Male Physical Endurance/*physiology Stimulation, Chemical Support, Non-U.S. Gov't

Staff

Professor Gary Ford
Jacobson Chair of Clinical Pharmacology