Total Ca2+ handling for E-C coupling in the whole heart: an integrative analysis.
We assessed total Ca2+ handling (transport, flux) in excitation-contraction (E-C) coupling in a beating left ventricle (LV). We developed a new integrative analysis method that utilizes the internal Ca2+ recirculation fraction (RF), O2 consumption (V(O2)) for Ca2+ handling, and O2 cost of Emax (contractility index) of the LV. We obtained the RF from the beat constant of the exponential decay component of the postextrasystolic potentiation, and the O2 cost of Emax from V(O2) measured at different Emax. Our equation calculated the unknown total Ca2+ handling, futile Ca2+ cycling, and Ca2+ reactivity of Emax from the RF and Ca2+ handling V(O2). The calculated total Ca2+ handling fell between 30 and 110 micromol/kg, depending on Emax and pathological conditions. Our method also allowed an assessment of futile Ca2+ cycling and Ca2+ reactivity of Emax in a beating LV. These data are not available using conventional methods. Our method can be used to better understand the pathophysiology of total Ca2+ handling in a beating heart.
Araki
J
J
Department of Physiology II, Okayama University Medical School, Japan.
Mohri
S
S
Iribe
G
G
Shimizu
J
J
Suga
H
H
D000818:Animals; D001696:Biomechanical Phenomena; D001794:Blood Pressure / Q000502:physiology; D002118:Calcium / Q000378:metabolism / Q000502:physiology*; D015220:Calcium Channels / Q000502:physiology; D004285:Dogs; D006321:Heart / Q000502:physiology*; D066298:In Vitro Techniques; D009200:Myocardial Contraction / Q000502:physiology*; D009206:Myocardium / Q000378:metabolism; D010101:Oxygen Consumption / Q000502:physiology; D013318:Stroke Volume / Q000502:physiology; D016276:Ventricular Function / Q000502:physiology
D015220:Calcium Channels; D002118:Calcium