title: Influence of hyperthyroidism on the superprecipitation response and Ca2+-sensitivity of natural actomyosin in cardiac and skeletal muscle.
abstract: In cardiac natural actomyosin prepared from hyperthyroid rabbits, the time of onset of the superprecipitation response was shortened by 58% and the rate of response was increased 4-fold compared with euthyroid animals. However, Ca2+-sensitivity of cardiac natural actomyosin prepared from either euthyroid or hyperthyroid rabbits was not changed over the range of 10(-7) to 6.6 . 10(-5) M free Ca2+ concentrations. Skeletal natural actomyosin prepared from either euthyroid or hyperthyroid rabbits showed a far higher Ca2+-sensitivity than cardiac natural actomyosin, but there was no difference in either time of onset or rate of superprecipitation response.
mesh_terms: D000205:Actomyosin / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D011232:Chemical Precipitation; D006321:Heart / Q000187:drug effects*; D006980:Hyperthyroidism / Q000139:chemically induced / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D009132:Muscles / Q000187:drug effects*; D011817:Rabbits
chemical_list: D000255:Adenosine Triphosphate; D000205:Actomyosin; D002118:Calcium