title: Relationship between initial chemical reactions and oxidative recovery metabolism for single isometric contractions of frog sartorius at 0 degrees C.
abstract: 1. Measurements of intitial chemical changes and recovery oxygen consumption (deltaO2) were made in unpoisoned aerobic frog sartorius muscles at 0 degrees C to provide independent measures of the chemical energy used for isometric tetani of various durations. 2. DeltaO2 was measured polarographically and increased in a curvilinear fashion with stimulus duration. For stimulations longer than 4 sec deltaO2 was a linear function of the tension-time integral. 3. Measurements of the changes in the content of phosphorylcreatine, 'free' creatine and inorganic phosphate were made in muscles rapidly frozen during a tetanus. The average of these quantities, delta approximately P, was used to measure the initial 'high energy' phosphate utilization. No break-down of 'high-energy' phosphate compounds was detected up to 200 sec after relaxation of tension. Changes in the content of ATP were not observed except for a small decrease (-0-25+/-0-1 mumole/g) in muscles tetanized for 1 sec. 4. Delta approximately P also increase curvilinearly with tetanus duration and, for tetanic durations greater than 4 sec, was a linear function of the tension-time integral. 5. Both deltaO2 and delta approximately P were quantitatively related by a constant scaling factor of about 4-3 (delta approximately P/deltaO2) throughout the range of tetanic durations studied. The constancy of this ratio.provides evidence against the hypothesis that a significant 'missing reaction' provides energy during any one portion of the tetanus. Several hypothesis may account for the numerical value of the ration delta approximately P/deltaO2.
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000332:Aerobiosis; D000818:Animals; D003401:Creatine / Q000378:metabolism; D004734:Energy Metabolism; D066298:In Vitro Techniques; D007700:Kinetics; D009119:Muscle Contraction; D009132:Muscles / Q000378:metabolism*; D010101:Oxygen Consumption; D010710:Phosphates / Q000378:metabolism; D011048:Polarography; D011894:Rana pipiens
chemical_list: D010710:Phosphates; D000255:Adenosine Triphosphate; D003401:Creatine