title: Responses of beta-adrenoceptor in rat soleus to phosphorus compound levels and/or unloading.
abstract: Responses of beta-adrenoceptor (beta-AR) in rat soleus to gravitational unloading and/or changes in the levels of phosphorus compounds by feeding either creatine or its analogue beta-guanidinopropionic acid (beta-GPA) were studied. A decrease in the density of beta-AR (about -35%) was induced by 10 days of hindlimb suspension, but the affinity of the receptor was unaffected. Suspension unloading tended to increase the levels of adenosine triphosphate and phosphocreatine and decrease inorganic phosphate. Even without unloading, the beta-AR density decreased after an oral creatine supplementation (about -20%), which also tended to elevate the high-energy phosphate levels in muscle. However, an elevation of beta-AR density was induced (about +36%) after chronic depletion of high-energy phosphates by feeding beta-GPA (about +125%). Data suggest that the density of beta-AR in muscle is elevated if the high-energy phosphate contents are chronically decreased and vice versa. However, it may not be directly related to the degree of muscle contractile activity.
authors.affiliation: Department of Physiology and Biomechanics, National Institute of Fitness and Sports, Kagoshima, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Ohira
authors.forename: K
authors.initials: K
authors.lastname: Saito
authors.forename: T
authors.initials: T
authors.lastname: Wakatsuki
authors.forename: W
authors.initials: W
authors.lastname: Yasui
authors.forename: T
authors.initials: T
authors.lastname: Suetsugu
authors.forename: K
authors.initials: K
authors.lastname: Nakamura
authors.forename: H
authors.initials: H
authors.lastname: Tanaka
authors.forename: T
authors.initials: T
authors.lastname: Asakura
mesh_terms: D000818:Animals; D003404:Creatinine / Q000378:metabolism; D006146:Guanidines / Q000378:metabolism / Q000493:pharmacokinetics / Q000494:pharmacology*; D007457:Iodine Radioisotopes; D020120:Iodocyanopindolol; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D009132:Muscles / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D010710:Phosphates / Q000378:metabolism; D010758:Phosphorus; D010869:Pindolol / Q000031:analogs & derivatives / Q000378:metabolism; D011422:Propionates / Q000378:metabolism / Q000493:pharmacokinetics / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000378:metabolism*; D012016:Reference Values; D014018:Tissue Distribution
chemical_list: D006146:Guanidines; D007457:Iodine Radioisotopes; D010710:Phosphates; D011422:Propionates; D011943:Receptors, Adrenergic, beta; D010758:Phosphorus; D020120:Iodocyanopindolol; D003404:Creatinine; D010869:Pindolol; C005775:guanidinopropionic acid