Exercise training improves left ventricular contractile response to beta-adrenergic agonist.
To determine whether endurance exercise training can improve left ventricular function in response to beta-adrenergic stimulation, young healthy sedentary subjects (10 women and 6 men) were studied before and after 12 wk of endurance exercise training. Training consisted of 3 days/wk of interval training (running and cycling) and 3 days/wk of continuous running for 40 min. The training resulted in an increase in maximal O2 uptake from 41.0 +/- 2 to 49.3 +/- 2 ml.kg-1.min-1 (P less than 0.01). Left ventricular function was evaluated by two-dimensional echocardiography under basal conditions and during beta-adrenergic stimulation induced by isoproterenol infusion. Fractional shortening (FS) under basal conditions was unchanged after training (36 +/- 1 vs. 36 +/- 2%). During the highest dose of isoproterenol, FS was 52 +/- 1% before and 56 +/- 1% after training (P less than 0.05). At comparable changes in end-systolic wall stress (sigma es), the increase in FS induced by isoproterenol was significantly larger after training (13 +/- 1 vs. 17 +/- 2%, P less than 0.01). Furthermore there was a greater decrease in end-systolic dimension at similar changes in sigma es in the trained state during isoproterenol infusion (-4.6 +/- 0.1 mm before vs. -7.0 +/- 0.1 mm after training, P less than 0.01). There were no concurrent changes in end-diastolic dimension between the trained and untrained states during isoproterenol infusion, suggesting no significant changes in preload at comparable levels of sigma es.(ABSTRACT TRUNCATED AT 250 WORDS)
Spina
R J
RJ
Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110.
Ogawa
T
T
Coggan
A R
AR
Holloszy
J O
JO
Ehsani
A A
AA
D000328:Adult; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D005260:Female; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D006801:Humans; D007545:Isoproterenol / Q000494:pharmacology*; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects* / Q000502:physiology; D010101:Oxygen Consumption / Q000502:physiology; D010806:Physical Education and Training; D010807:Physical Endurance / Q000502:physiology; D016277:Ventricular Function, Left / Q000187:drug effects / Q000502:physiology
D007545:Isoproterenol