title: Adaptations of the beta-adrenoceptor-adenylyl cyclase system in rat skeletal muscle to endurance physical training.
abstract: beta-Adrenergic mechanisms may be important in the adaptation of skeletal muscle to endurance training. beta-Adrenergic signal transduction was examined in the gastrocnemius muscle of rats submitted to a progressive, 12-week treadmill running program and compared with sedentary controls. beta-Adrenoceptor density was significantly lower in exercised rats than in controls. The affinity constant for [125I]-(-) iodocyanopindolol binding was not different among the various groups. Adenosine cyclic monophosphate formation was significantly decreased in trained animals when isoproterenol plus guanosine triphosphate or forskolin plus Mn2+ were used to stimulate adenylyl cyclase. Immunoblot analyses revealed that the amount of the alpha-subunit of stimulatory guanine nucleotide-binding protein (Gs,alpha), both the small and the large isoforms, also decreased with physical exercise. Thus, the present report shows that endurance training results in alterations in beta-adrenergic receptor density, adenylyl cyclase activity and Gs protein level in rat gastrocnemius muscle.
authors.affiliation: Departamento de Bioquímica y Biología Molecular I, Fac. C.C. Químicas, Universidad Complutense, E-28040 Madrid, Spain.
authors.forename: J L
authors.initials: JL
authors.lastname: Nieto
authors.forename: I
authors.initials: I
authors.lastname: Diaz-Laviada
authors.forename: J M
authors.initials: JM
authors.lastname: Malpartida
authors.forename: I
authors.initials: I
authors.lastname: Galve-Roperh
authors.forename: A
authors.initials: A
authors.lastname: Haro
mesh_terms: D000222:Adaptation, Physiological; D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D019204:GTP-Binding Proteins / Q000378:metabolism; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000502:physiology*; D010805:Physical Conditioning, Animal; D010807:Physical Endurance; D051381:Rats; D017208:Rats, Wistar; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*
chemical_list: D011943:Receptors, Adrenergic, beta; D019204:GTP-Binding Proteins; D000262:Adenylyl Cyclases