Role of beta-adrenergic mechanisms in exercise training-induced metabolic changes in respiratory and locomotor muscle.
To test the hypothesis that beta-adrenergic stimulation is required for the normal increase in oxidative capacity of respiratory and locomotor skeletal muscle in response to exercise training, we examined the effects of beta-blockade on muscle oxidative capacity in trained and sedentary rats. Thirty-four female adult Sprague-Dawley rats were randomly divided into four experimental groups: 1) trained+propranolol (TP); 2) trained + sham injection (TS); 3) sedentary + propranolol (SP); and 4) sedentary + sham injection (SS). Training increased (p < 0.05) citrate synthase (CS) activity in the plantaris (+29%) and costal diaphragm (+12%) of TS animals compared to SS animals. In contrast, training did not (p > 0.05) increase costal diaphragm CS activity in TP animals compared to the SS group. Further, although training increased (p < 0.05) plantaris CS activity in the TP group (+18%) compared to the SP group, the training-induced increase in muscle CS activity was 11% lower (p < 0.05) than observed in TS animals. Collectively, these results suggest that beta-adrenergic mechanisms may play a role in the normal training-induced increase in oxidative capacity in both respiratory and locomotor skeletal muscles.
Powers
S K
SK
Department of Exercise and Sport Sciences, University of Florida, Gainesville, USA.
Wade
M
M
Criswell
D
D
Herb
R A
RA
Dodd
S
S
Hussain
R
R
Martin
D
D
D000222:Adaptation, Physiological / Q000502:physiology*; D000818:Animals; D005260:Female; D018485:Muscle Fibers, Skeletal / Q000502:physiology; D018482:Muscle, Skeletal / Q000737:chemistry / Q000502:physiology*; D009218:Myosins / Q000032:analysis; D010805:Physical Conditioning, Animal / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011943:Receptors, Adrenergic, beta / Q000502:physiology*; D012132:Respiratory Muscles / Q000737:chemistry / Q000502:physiology*
D011943:Receptors, Adrenergic, beta; D009218:Myosins