title: Functions of selected biochemical systems from the exercised-trained dog heart.
abstract: Mitochondria and sarcoplasmic reticulum (SR) fractions were isolated from exercised-trained (E-T) and sedentary control dog hearts. Measurements of mitochondrial respiratory functions indicated no changes in energy-producing (ATP synthesis) capacity in mitochondria from E-T compared to control dog hearts. However, the ability of isolated mitochondria from E-T hearts to retain accumulated calcium was markedly decreased compared to controls. Inhibition of mitochondrial rates of calcium uptake with the inhibitor, ruthenium red, revealed fewer binding and/or transport sites in mitochondrial membranes from exercised-trained heart preparations. ATP-dependent binding (- oxalate) and uptake (+ oxalate) of calcium by SR preparations from E-T hearts were unchanged compared to controls. In contrast, significant differences in the rates of release of bound calcium were found in SR isolated from E-T hearts. Total myocardial protein, nucleic acids, and connective tissue levels were unchanged in E-T hearts compared to controls. The results suggest subtle changes are occurring in the energy-utilizing mechanism(s) involving calcium transport of the myocardial cell during exercise training. These changes may be related to alterations in the performance of the exercised-trained heart.
mesh_terms: D000818:Animals; D001665:Binding Sites; D001693:Biological Transport, Active / Q000187:drug effects; D002118:Calcium / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D004285:Dogs; D006909:Hydroxyproline / Q000378:metabolism; D008931:Mitochondria, Muscle / Q000378:metabolism*; D009124:Muscle Proteins / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism* / Q000648:ultrastructure; D010085:Oxidative Phosphorylation; D010101:Oxygen Consumption; D010805:Physical Conditioning, Animal; D012313:RNA / Q000378:metabolism; D012430:Ruthenium Red / Q000494:pharmacology; D012519:Sarcoplasmic Reticulum / Q000378:metabolism
chemical_list: D009124:Muscle Proteins; D012430:Ruthenium Red; D012313:RNA; D004247:DNA; D006909:Hydroxyproline; D002118:Calcium