Effect of contractile activity on rat skeletal muscle beta-adrenoceptor properties.
The effect of fiber type and endurance exercise training on skeletal muscle beta-adrenoceptor properties were assessed using a direct radioligand binding technique. Six separate muscles, composed of a variety of different fiber types, were examined in treadmill trained and sedentary rats. In trained animals, sarcolemmal preparations from heart and slow twitch soleus muscle exhibited a significantly greater receptor concentration than membranes from white fast twitch glycolytic fibers of the vastus lateralis. No significant changes were observed between trained and sedentary rat muscle beta-adrenoceptor density (beta max, fmole/mg protein) or affinity (Kd, nM) within each muscle type, despite significantly increased myocardial/body weight ratios and skeletal muscle enzyme adaptations associated with the exercise program. These results suggest that muscle beta-adrenoceptor properties may be influenced in part by the motor nerve innervation to that muscle, and are further discussed with respect to a possible relationship between exercise intensity and receptor regulation.
D000818:Animals; D001835:Body Weight; D006321:Heart / Q000033:anatomy & histology; D008297:Male; D009119:Muscle Contraction; D009132:Muscles / Q000502:physiology*; D009206:Myocardium / Q000378:metabolism; D009929:Organ Size; D010101:Oxygen Consumption; D010807:Physical Endurance; D005082:Physical Exertion; D051381:Rats; D011919:Rats, Inbred Strains; D011943:Receptors, Adrenergic, beta / Q000502:physiology*; D012508:Sarcolemma / Q000378:metabolism
D011943:Receptors, Adrenergic, beta