Calcium kinetics and energetics in myocardium. Simulation study.
We carried out a simulation study to obtain insight into the relation between calcium (Ca2+) transients and energy for handling Ca2+ in excitation-contraction (EC) coupling. The simulation incorporated basic Ca2+ kinetics among total released Ca2+ from sarcoplasmic reticulum (SR), myoplasmic free Ca2+ ion concentration, and troponin (Tn)-Ca complex concentration ([TnCa]). The total Ca2+ released from the SR was arbitrarily set as an impulse and three rate constants were used for Ca2+ binding to Tn, Ca2+ dissociation from Tn, and Ca2+ uptake by SR. The results showed that the peak Ca2+ transient varies widely as a reciprocal of the Ca2+ sensitivity of the contractile machinery, despite constant total released Ca2+ and hence, a constant energy for Ca2+ handling. This result suggests a disproportate relationship between the magnitude of Ca2+ transients and the energy for Ca2+ handling when the Ca2+ sensitivity of contractile machinery changes.
Suga
H
H
Department of Cardiovascular Dynamics, National Cardiovascular Center Research Institute, Osaka, Japan.
Goto
Y
Y
Futaki
S
S
Kawaguchi
O
O
Yaku
H
H
Hata
K
K
Takasago
T
T
D002118:Calcium / Q000378:metabolism*; D004734:Energy Metabolism; D007700:Kinetics; D008955:Models, Cardiovascular; D009200:Myocardial Contraction; D009206:Myocardium / Q000378:metabolism*; D010101:Oxygen Consumption; D012519:Sarcoplasmic Reticulum / Q000378:metabolism; D014336:Troponin / Q000378:metabolism
D014336:Troponin; D002118:Calcium