Enhanced inotropic response to dobutamine in strength-trained subjects with left ventricular hypertrophy.
To determine whether strength-trained individuals with physiological concentric left ventricular (LV) hypertrophy exhibit enhanced inotropic responses to catecholamines, we studied 11 bodybuilders, aged 33.0 +/- 2 (SE) yr old, and 10 sedentary healthy subjects, aged 31.3 +/- 2.4 yr old, at baseline and during infusion of incremental doses of dobutamine after atropine. The bodybuilders had larger LV mass, posterior wall and septal wall thicknesses, and wall thickness-to-radius ratio, assessed with two-dimensional echocardiography, than did the sedentary subjects. There was a significant correlation between LV mass and lean body mass irrespective of training status. Baseline LV fractional shortening was similar in the two groups. There was a greater inotropic response to dobutamine in the strength-trained individuals, as evidenced by a steeper slope of the fractional shortening-end-systolic wall stress relationship with a higher y-axis intercept and by a shallower end-systolic wall stress-end systolic diameter relationship without changes in end-diastolic diameter. The heart rate response to dobutamine was attenuated in the strength-trained athletes. There was a significant correlation (r = 0.604, P < 0.05) between the inotropic sensitivity to dobutamine and LV mass normalized for lean body mass in the bodybuilders. The data suggest that concentric LV physiological hypertrophy in the resistance-trained individuals is associated with enhanced inotropic but not chronotropic responses to catecholamines.
Suman
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OE
Section of Applied Physiology, Division of Geriatrics and Gerontology, and Claude D. Pepper Older Americans Independence Center, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Hasten
D
D
Turner
M J
MJ
Rinder
M R
MR
Spina
R J
RJ
Ehsani
A A
AA
D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D001285:Atropine / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D001835:Body Weight; D002319:Cardiovascular System / Q000187:drug effects / Q000503:physiopathology; D004280:Dobutamine / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006352:Heart Ventricles / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D017379:Hypertrophy, Left Ventricular / Q000503:physiopathology*; D008297:Male; D018727:Muscarinic Antagonists / Q000494:pharmacology; D009200:Myocardial Contraction / Q000187:drug effects*; D010101:Oxygen Consumption / Q000187:drug effects; D010807:Physical Endurance / Q000502:physiology*; D011976:Receptors, Muscarinic / Q000187:drug effects
D000318:Adrenergic beta-Agonists; D018727:Muscarinic Antagonists; D011976:Receptors, Muscarinic; D004280:Dobutamine; D001285:Atropine