Calcium regulation in heart cells. The interaction of mitochondrial and sarcoplasmic reticulum with troponin-bound calcium.
A study has been carried out of the interaction of dog heart mitochondria and sarcoplasmic reticulum with Ca2+ bound to troponin or to its Ca2+-binding component (troponin-C). Both organelles are able to release more than 80% of the Ca2+ bound to the two proteins. However, sarcoplasmic reticulum is only able to do so in the presence of oxalate, whereas mitochondria are active also in the absence of permeant Ca-complexing anions. On the other hand, calcium uptake in heart mitochondria is severely inhibited by Mg2+. The results are discussed with reference to the problem of the control of Ca2+ in heart sarcoplasm.
D000818:Animals; D001665:Binding Sites; D001693:Biological Transport, Active; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D004285:Dogs; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D008861:Microsomes / Q000187:drug effects / Q000378:metabolism; D008931:Mitochondria, Muscle / Q000187:drug effects / Q000378:metabolism*; D009124:Muscle Proteins / Q000378:metabolism*; D009206:Myocardium; D010070:Oxalates / Q000494:pharmacology; D011485:Protein Binding; D012519:Sarcoplasmic Reticulum / Q000378:metabolism*; D014336:Troponin / Q000378:metabolism*
D009124:Muscle Proteins; D010070:Oxalates; D014336:Troponin; D008274:Magnesium; D002118:Calcium