scholarly journals Ryanodine Decreases Internal Ca2+ Recirculation Fraction of the Canine Heart as Studied by Postextrasystolic Transient Alternans.

1997 ◽  
Vol 47 (6) ◽  
pp. 521-530 ◽  
Author(s):  
Yoshiki HATA ◽  
Juichiro SHIMIZU ◽  
Shingo HOSOGI ◽  
Hiromi MATSUBARA ◽  
Junichi ARAKI ◽  
...  
Keyword(s):  
Canine Heart ◽  
Recirculation Fraction

Energy-wasteful total Ca2+ handling underlies increased O2 cost of contractility in canine stunned heart

2000 ◽  
Vol 278 (5) ◽  
pp. H1464-H1472 ◽  
Author(s):  
Shinyu Lee ◽  
Junichi Araki ◽  
Takeshi Imaoka ◽  
Masaki Maesako ◽  
Gentaro Iribe ◽  
...  
Keyword(s):  
Exponential Decay ◽  
Myocardial Stunning ◽  
Left Ventricular ◽  
Canine Heart ◽  
Ventricular Contractility ◽  
Left Ventricular Contractility ◽  
Postextrasystolic Potentiation ◽  
Decay Component ◽  
Recirculation Fraction ◽  
Integrative Method

Postischemic myocardial stunning halved left ventricular contractility [end-systolic maximum elastance ( E max)] and doubled the O2 cost of E max in excised cross-circulated canine heart. We hypothesized that this increased O2 cost derived from energy-wasteful myocardial Ca2+ handling consisting of a decreased internal Ca2+ recirculation, some futile Ca2+ cycling, and a depressed Ca2+ reactivity of E max. We first calculated the internal Ca2+ recirculation fraction (RF) from the exponential decay component of postextrasystolic potentiation. Stunning significantly accelerated the decay and decreased RF from 0.63 to 0.43 on average. We then combined the decreased RF with the halved E maxand its doubled O2 cost and analyzed total Ca2+handling using our recently developed integrative method. We found a decreased total Ca2+ transport and a considerable shift of the relation between futile Ca2+ cycling and Ca2+ reactivity in an energy-wasteful direction in the stunned heart. These changes in total Ca2+ handling reasonably account for the doubled O2 cost of E max in stunning, supporting the hypothesis.

A new integrative method to quantify total Ca2+ handling and futile Ca2+ cycling in failing hearts

1998 ◽  
Vol 275 (6) ◽  
pp. H2325-H2333 ◽  
Author(s):  
Juichiro Shimizu ◽  
Junichi Araki ◽  
Ju Mizuno ◽  
Shinyu Lee ◽  
Yi Syuu ◽  
...  
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Left Ventricle ◽  
Present Method ◽  
Direct Application ◽  
Cardiac Contraction ◽  
Canine Heart ◽  
Contraction Coupling ◽  
Before And After ◽  
Recirculation Fraction ◽  
Integrative Method

Ca2+ handling in excitation-contraction coupling requires considerable O2 consumption (Vo 2) in cardiac contraction. We have developed an integrative method to quantify total Ca2+ handling in normal hearts. However, its direct application to failing hearts, where futile Ca2+ cycling via the Ca2+-leaky sarcoplasmic reticulum (SR) required an increased Ca2+handling Vo 2, was not legitimate. To quantify total Ca2+ handling even in such failing hearts, we combined futile Ca2+ cycling with Ca2+ handling Vo 2 and the internal Ca2+ recirculation fraction via the SR. We applied this method to the canine heart mechanoenergetics before and after intracoronary ryanodine at nanomolar concentrations. We found that total Ca2+ handling per beat was halved after the ryanodine treatment from ∼60 μmol/kg left ventricle before ryanodine. We also found that futile Ca2+ cycling via the SR increased to >1 cycle/beat after ryanodine from presumably zero before ryanodine. These results support the applicability of the present method to the failing hearts with futile Ca2+ cycling via the SR.

Postextrasystolic contractile decay always contains exponential and alternans components in canine heart

2000 ◽  
Vol 279 (1) ◽  
pp. H225-H233 ◽  
Author(s):  
Juichiro Shimizu ◽  
Junichi Araki ◽  
Gentaro Iribe ◽  
Takeshi Imaoka ◽  
Satoshi Mohri ◽  
...  
Keyword(s):  
Heart Rate ◽  
Left Ventricle ◽  
Experimental Evidence ◽  
Canine Heart ◽  
Determination Method ◽  
Decay Constants ◽  
Decay Component ◽  
Alternative Method ◽  
Coupling Interval ◽  
Recirculation Fraction

In isolated, blood-perfused canine hearts, postextrasystolic potentiation (PESP) decays monotonically after a noncompensatory pause following a spontaneous extrasystole (ES). The monotonic PESP decay yields myocardial internal Ca2+ recirculation fraction (RF). We have found that after a compensatory pause (CP), PESP decays in alternans, consisting of an exponential and a sinusoidal decay component. We have proposed that this exponential component also yields RF. In the present study, we examined the reliability of this alternative method by widely changing the ES coupling interval (ESI), CP, and heart rate in the canine excised, cross-circulated left ventricle. We found that all PESP decays consisted of the sum of an exponential and a sinusoidal decay component of variable magnitudes whether a CP existed or not. Their decay constants as well as the calculated RF were independent of the ESI and CP. This confirmed the utility of our alternative RF determination method regardless of the ESI, CP, and heart rate. Direct experimental evidence of Ca2+ dynamics supportive of this alternative method, however, remains to be obtained.

scholarly journals Load Independence of Temperature-Dependent Ca2+ Recirculation Fraction in Canine Heart

2004 ◽  
Vol 54 (4) ◽  
pp. 319-329 ◽  
Author(s):  
J. Mizuno ◽  
S. Mohri ◽  
J. Shimizu ◽  
S. Suzuki ◽  
T. Mikane ◽  
...  
Keyword(s):  
Canine Heart ◽  
Temperature Dependent ◽  
Recirculation Fraction

No evidence of direct cardiac action of leucine-enkephalin in canine heart-lung preparation.

1984 ◽  
Vol 34 (2) ◽  
pp. 351-355 ◽  
Author(s):  
Shozo KOYAMA ◽  
Nobuyuki TERADA ◽  
Yumiko SHIOJIMA ◽  
Toru TAKEUCHI
Keyword(s):  
Canine Heart ◽  
Leucine Enkephalin ◽  
Cardiac Action ◽  
Lung Preparation

Biological Response to Bard Clamshell Septal Occluders in the Canine Heart

Circulation ◽  
1996 ◽  
Vol 93 (7) ◽  
pp. 1459-1463 ◽  
Author(s):  
Micheal A. Kuhn ◽  
Larry A. Latson ◽  
John P. Cheatham ◽  
Bruce McManus ◽  
James M. Anderson ◽  
...  
Keyword(s):  
Biological Response ◽  
Canine Heart

Low-Flow Ischemia Leads to Translocation of Canine Heart GLUT-4 and GLUT-1 Glucose Transporters to the Sarcolemma In Vivo

Circulation ◽  
1997 ◽  
Vol 95 (2) ◽  
pp. 415-422 ◽  
Author(s):  
Lawrence H. Young ◽  
Yin Renfu ◽  
Raymond Russell ◽  
Xiaoyue Hu ◽  
Michael Caplan ◽  
...  
Keyword(s):  
Glucose Transporters ◽  
Low Flow ◽  
Canine Heart ◽  
Glut 1 ◽  
Glut 4

Characteristics of the β-Adrenergic Receptor Complex in the Epicardial Border Zone of the 5-Day Infarcted Canine Heart

Circulation ◽  
1995 ◽  
Vol 91 (11) ◽  
pp. 2824-2833 ◽  
Author(s):  
Susan F. Steinberg ◽  
HongLu Zhang ◽  
Elena Pak ◽  
Geraldine Pagnotta ◽  
Penelope A. Boyden
Keyword(s):  
Adrenergic Receptor ◽  
Border Zone ◽  
Canine Heart ◽  
Receptor Complex

Vesnarinone Limits Infarct Size via Adenosine-Dependent Mechanisms in the Canine Heart

Circulation ◽  
1997 ◽  
Vol 95 (8) ◽  
pp. 2108-2114 ◽  
Author(s):  
Masafumi Kitakaze ◽  
Tetsuo Minamino ◽  
Hiroharu Funaya ◽  
Koichi Node ◽  
Yoshiro Shinozaki ◽  
...  
Keyword(s):  
Infarct Size ◽  
Canine Heart
Sign in / Sign up

Export Citation Format

Share Document