TY - JOUR
T1 - Energy for Myocardial Ca2+ handling per beat increases with heart rate in excised cross-circulated canine heart
AU - Kiyooka, Takahiko
AU - Oshima, Yu
AU - Fujinaka, Waso
AU - Iribe, Gentaro
AU - Mohri, Satoshi
AU - Shimizu, Juichiro
PY - 2014/4
Y1 - 2014/4
N2 - Objective: Although tachycardia is well known to increase cardiac oxygen consumption (Vo2) per min, the relationship between Vo2 for excitation-contraction (E-C) coupling per beat and heart rate change over its full working range still remains controversial. Methods: To elucidate this relationship, we varied heart rate over a reasonably wide range (60-180 beat/min) and studied the relationship between left ventricular (LV) Emax (load-independent contractility index), PVA (pressure-volume area)-independent Vo2, and basal metabolic Vo2 in nine excised, cross-circulated canine hearts. Results: PVA-independent Vo2 per min significantly increased linearly with increasing heart rate while Emax remained unchanged. Basal metabolic Vo2per min was measured under KCl arrest. E-C coupling Vo2 per min obtained by subtracting the constant basal metabolic Vo2 from the PVA-independent Vo2 also significantly increased linearly with increasing heart rate. However, PVA-independent Vo2 per beat significantly decreased with increasing heart rate. In contrast, E-C coupling Vo2 per beat, as well as that normalized to Emax, slightly but significantly increased with increasing heart rate. Conclusion; The E-C coupling energy for myocardial Ca2+ handling increases with heart rate despite constant contractility in the left ventricle of the excised cross-circulated canine heart.
AB - Objective: Although tachycardia is well known to increase cardiac oxygen consumption (Vo2) per min, the relationship between Vo2 for excitation-contraction (E-C) coupling per beat and heart rate change over its full working range still remains controversial. Methods: To elucidate this relationship, we varied heart rate over a reasonably wide range (60-180 beat/min) and studied the relationship between left ventricular (LV) Emax (load-independent contractility index), PVA (pressure-volume area)-independent Vo2, and basal metabolic Vo2 in nine excised, cross-circulated canine hearts. Results: PVA-independent Vo2 per min significantly increased linearly with increasing heart rate while Emax remained unchanged. Basal metabolic Vo2per min was measured under KCl arrest. E-C coupling Vo2 per min obtained by subtracting the constant basal metabolic Vo2 from the PVA-independent Vo2 also significantly increased linearly with increasing heart rate. However, PVA-independent Vo2 per beat significantly decreased with increasing heart rate. In contrast, E-C coupling Vo2 per beat, as well as that normalized to Emax, slightly but significantly increased with increasing heart rate. Conclusion; The E-C coupling energy for myocardial Ca2+ handling increases with heart rate despite constant contractility in the left ventricle of the excised cross-circulated canine heart.
KW - End-systolic pressure-volume relation
KW - Excitation-contraction coupling
KW - Myocardial oxygen consumption
KW - Ventricular energetics
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M3 - Article
C2 - 24733598
AN - SCOPUS:84898823343
VL - 39
SP - 51
EP - 58
JO - Tokai Journal of Experimental and Clinical Medicine
JF - Tokai Journal of Experimental and Clinical Medicine
SN - 0385-0005
IS - 1
ER -