Document Detail

Effects of thapsigargin and KCl on the O2 use of the excised blood-perfused rat heart.
MedLine Citation:
PMID:  9799665     Owner:  NLM     Status:  MEDLINE    
We have already reported a curvilinear end-systolic pressure-volume relation and a linear oxygen consumption per beat (Vo2)-systolic pressure-volume area (PVA) relation of the left ventricle in the rat blood-perfused whole heart preparation. Recently, we have proposed that a PVA at an appropriate left-ventricular end-diastolic volume (0.15 ml/g), such as PVA0.15 and the Vo2 intercept (minimally loaded Vo2) of the Vo2-PVA relation, can be good indexes for assessing rat left-ventricular mechanoenergetics. The minimally-loaded Vo2 would mainly consist of Vo2 for Ca 2+ handling in the excitation-contraction (E-C) coupling and basal metabolism. However, the fraction of the Vo2 by the sarcoplasmic reticulum (SR) Ca2+-ATPase in the total Ca2+ handling Vo2 has not yet been examined. To study this for the first time, we investigated the effects of thapsigargin and KCl on left-ventricular mechanoenergetics. Blockade of the SR Ca2+ pump by thapsigargin (2.5 micromol/l) decreased PVA 0. 15 by 65% and decreased the Vo2 intercept by 40% without a change in the slope of the Vo2-PVA relation. We measured the basal metabolic Vo2 by intracoronary KCl and found a 75% decrease in the Vo2 intercept. We conclude that the minimally-loaded Vo2 mainly consists of Vo2 for Ca2+ handling in the E-C coupling (at least 40% is consumed by the SR Ca2+ ATPase) and basal metabolism (25%).
Y Hata; T Sakamoto; S Hosogi; T Ohe; H Suga; M Takaki
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of molecular and cellular cardiology     Volume:  30     ISSN:  0022-2828     ISO Abbreviation:  J. Mol. Cell. Cardiol.     Publication Date:  1998 Oct 
Date Detail:
Created Date:  1998-12-16     Completed Date:  1998-12-16     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0262322     Medline TA:  J Mol Cell Cardiol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  2137-43     Citation Subset:  IM    
Copyright Information:
Copyright 1998 Academic Press
Department of Physiology II, Okayama University Medical School, 2-5-1 Shikata-cho, Okayama 700-8558, Japan.
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MeSH Terms
Calcium / metabolism
Heart / drug effects*
Myocardial Contraction
Myocardium / metabolism*
Oxygen Consumption / drug effects*
Potassium Chloride / pharmacology*
Rats, Wistar
Thapsigargin / pharmacology*
Reg. No./Substance:
67526-95-8/Thapsigargin; 7440-70-2/Calcium; 7447-40-7/Potassium Chloride

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