title: Coordinated fast-to-slow transitions of myosin and SERCA isoforms in chronically stimulated muscles of euthyroid and hyperthyroid rabbits.
abstract: Changes in the patterns of myosin heavy chain (MHC) isoforms, isomyosins, and Ca(2+)-ATPase (SERCA) isoforms were studied in long-term (72 d) stimulated fast-twitch extensor digitorum longus (EDL) and tibialis anterior (TA) muscles of euthyroid and hyperthyroid rabbits. The chronic low-frequency stimulation-induced fast-to-slow transitions in MHC isoforms, isomyosins and SERCA isoforms were pronounced in muscles from euthyroid rabbits, but less pronounced in muscles from hyperthyroid rabbits. Thus, hyperthyroidism counteracted to same extent the stimulation-induced fast-to-slow transition. Analyses of all parameters were performed on the same individual muscles, providing information on the co-ordinated expression of SERCA and myosin isoforms. A high correlation (r = 0.97) was detected between relative concentrations of slow SERCA2a and slow MHCI isoforms. This correlation persisted under all experimental conditions, suggesting a co-ordinated expression of slow myosin and Ca(2+)-ATPase isoforms. Conversely, fast SERCA1a was correlated to fast myosin isoforms as a whole.
authors.affiliation: Fakultät für Biologie, Universität Konstanz, Germany.
authors.forename: N
authors.initials: N
authors.lastname: Hämäläinen
authors.forename: D
authors.initials: D
authors.lastname: Pette
mesh_terms: D000818:Animals; D000252:Calcium-Transporting ATPases / Q000302:isolation & purification / Q000378:metabolism*; D004558:Electric Stimulation; D004591:Electrophoresis, Polyacrylamide Gel; D006980:Hyperthyroidism / Q000503:physiopathology*; D007527:Isoenzymes / Q000302:isolation & purification / Q000378:metabolism; D018656:Muscle Fibers, Fast-Twitch / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology* / Q000503:physiopathology; D018995:Myosin Heavy Chains / Q000378:metabolism; D009218:Myosins / Q000302:isolation & purification / Q000378:metabolism*; D011817:Rabbits; D012016:Reference Values; D012044:Regression Analysis; D013961:Thyroid Gland / Q000502:physiology* / Q000503:physiopathology; D014638:Vanadates / Q000494:pharmacology
chemical_list: D007527:Isoenzymes; D014638:Vanadates; D018995:Myosin Heavy Chains; D009218:Myosins; D000252:Calcium-Transporting ATPases