Key result
Theophylline attenuates age-related isoproterenol resistance, lowering the required dose by ~57% in elderly subjects.
Why the study?
The mechanism by which aging decreases the cardiac chronotropic response to beta-adrenoceptor stimulation in humans is unknown.
Does theophylline improve the chronotropic response to isoproterenol in healthy elderly subjects?
Population
Sixteen healthy elderly (67.1 +/- 1.3 yrs) and sixteen healthy young (26.1 +/- 0.6 yrs) subjects
Comparison
Baseline vs after 30-min theophylline (6.5 mg/kg) infusion
Design
Interventional study with adenosine receptor antagonist theophylline
Authors
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Theophylline may enhance chronotropic responsiveness in healthy elderly; extends mechanistic evidence for adenosine but leaves clinical utility open.
Does theophylline improve the chronotropic response to isoproterenol in healthy elderly subjects?
Absolute Event Rate: 0.43% vs 0.82%
p-value: p=<.05
Endogenous adenosine contributes to the age-related decline in cardiac chronotropic response to beta-adrenergic stimulation.
Suteparuk et al. (1995) studied Healthy aging (n=32). Theophylline vs. Young subjects was evaluated on Dose ratio of isoproterenol required to increase heart rate by 25 bpm (I25 after/before theophylline) (p=<.05). Theophylline administration attenuated age-related resistance to isoproterenol, with a greater reduction in required isoproterenol dose in elderly versus young subjects (dose ratio 0.43 vs 0.82; p<0.05).
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