Load independence of temperature-dependent Ca2+ recirculation fraction in canine heart

The Japanese Journal of Physiology
J MizunoHiroyuki Suga


Intramyocardial Ca(2+) recirculation fraction (RF) critically determines the economy of excitation-contraction coupling. RF is obtainable from the exponential decay of the postextrasystolic potentiation of left ventricular (LV) contractility. We have shown that RF remains unchanged despite increasing LV volume (LVV) at normothermia, but decreases with increasing temperature at a constant LVV. However, it remains unknown whether the temperature-dependent RF was not due to the simultaneously changed peak LV pressure (LVP) at a constant LVV. We hypothesized that this temperature-dependent RF would be independent of the simultaneous change in LVP. We used nine excised, cross-circulated canine hearts and allowed their LVs to contract isovolumically. During stable regular beats at 500 msec intervals, we inserted an extrasystolic beat at 360 msec interval followed by the postextrasystolic beats (PESs) at 500 msec intervals. We equalized the temperature-dependent peak LVPs of the regular beats at 36 degrees C and 38 degrees C to the peak LVP level of the stable regular beat at 33 degrees C by adjusting LVV. We fitted the same equation: nEmax = a.exp[-(i - 1)/tau(e)] + b.exp[-(i - 1)/tau(s)]cos[pi(i - 1)] + 1, used before to the normali...Continue Reading


Apr 1, 1990·Physiological Reviews·Hiroyuki Suga
Mar 21, 1985·Journal of Theoretical Biology·D AdlerG A Klassen
Aug 1, 1982·Acta Physiologica Scandinavica·B Wohlfart
Jan 1, 1982·Pharmacology & Therapeutics·B Wohlfart, M I Noble
Jan 1, 1994·Heart and Vessels·J ArakiHiroyuki Suga
Jan 1, 1995·The Japanese Journal of Physiology·Juichiro ShimizuHiroyuki Suga
Dec 9, 1998·The American Journal of Physiology·Juichiro ShimizuHiroyuki Suga
Jul 17, 1999·The American Journal of Physiology·Takeshi MikaneHiroyuki Suga
Oct 30, 1999·Heart and Vessels·J MizunoHiroyuki Suga
Apr 25, 2000·American Journal of Physiology. Heart and Circulatory Physiology·S LeeHiroyuki Suga
Jul 19, 2000·American Journal of Physiology. Heart and Circulatory Physiology·Juichiro ShimizuHiroyuki Suga
Nov 22, 2000·American Journal of Physiology. Heart and Circulatory Physiology·A SaekiHiroyuki Suga
Dec 20, 2000·The Japanese Journal of Physiology·M MaesakoHiroyuki Suga
Jan 15, 2002·American Journal of Physiology. Heart and Circulatory Physiology·J MizunoHiroyuki Suga
Feb 16, 2002·The Japanese Journal of Physiology·J MizunoHiroyuki Suga
Jun 22, 2002·Cellular Physiology and Biochemistry : International Journal of Experimental Cellular Physiology, Biochemistry, and Pharmacology·Leanne GrobanThomas E Nelson
Apr 16, 2003·Journal of Biomechanics·Hiroyuki Suga
Aug 2, 2003·American Journal of Physiology. Regulatory, Integrative and Comparative Physiology·Yi SyuuHiroyuki Suga

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