Temperature-dependence of tension development by glycerinated muscle fibers of rabbit psoas in Mg-ITP solution.
The isometric tension of single fibers isolated from glycerinated rabbit psoas muscle was measured at various temperatures using Mg-ITP as a substrate. The tension developed in Mg-ITP decreased linearly as the temperature was reduced from 24 degrees C to 4 degrees C. Myosin formed the myosin--product complex predominantly via ATP hydrolysis at the burst site during Mg-ATP hydrolysis, irrespective of temperature, and the tension developed in Mg-ATP decreased linearly as the temperature decreased (Yoshida and Tawada (1976) J. Biochem. 80, 861). During Mg-ITP hydrolysis, myosin forms the myosin*-product complex predominantly at the burst site above 20 degrees C, while myosin forms the myosin*-substrate complex below 8 degrees C (Hozumi (1976) Eur. J. Biochem. 63, 241). However, the temperature dependence of tension development in Mg-ITP is linear, as with Mg-ATP, as mentioned above. This temperature dependence is not compatible with some muscle models which assume the formation of the myosin*-product complex by cross-bridges prior to combination with actin during contraction.
D000818:Animals; D005990:Glycerol; D007292:Inosine Nucleotides / Q000494:pharmacology*; D007293:Inosine Triphosphate / Q000494:pharmacology*; D008274:Magnesium / Q000494:pharmacology*; D009119:Muscle Contraction / Q000187:drug effects*; D009132:Muscles / Q000378:metabolism / Q000502:physiology; D015879:Myosin Subfragments / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism; D011817:Rabbits; D013696:Temperature
D007292:Inosine Nucleotides; D015879:Myosin Subfragments; D010710:Phosphates; D007293:Inosine Triphosphate; D008274:Magnesium; D005990:Glycerol