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Updated: Jun 22, 2026

Assessment of Sarcoplasmic Reticulum Calcium Reserve and Intracellular Diastolic Calcium Removal in Isolated Ventricular Cardiomyocytes
Published on: September 18, 2017
Myocardial stunning is associated with impaired calcium uptake by sarcoplasmic reticulum
Sanjay Kumar1, Roger J C Hall, Ali R Mani
1National Heart & Lung Institute, Imperial College, London, UK. S.Kumar3@rbht.nhs.uk
Abstract:
Myocardial stunning (temporary post-ischaemic contractile dysfunction) may be caused by oxidative stress and/or impaired myocyte calcium homeostasis. Regional myocardial stunning was induced in open-chest pigs (segment shortening reduced to 68.3+/-4.7% of baseline) by repetitive brief circumflex coronary occlusion (I/R). Reduced glutathione was depleted in stunned myocardium (1.34+/-0.06 vs. 1.77+/-0.11 nmol/mg, p=0.02 vs. remote myocardium) indicating regional oxidant stress, but no regional differences were observed in protein-bound 3-nitrotyrosine or S-nitrosothiol content. Repetitive I/R did not affect myocardial quantities of the sarcolemmal sodium-calcium exchanger, L-type channel, SR calcium ATPase and phospholamban, or the kinetics of ligand binding to L-type channels and SR calcium release channels. However, initial rates of oxalate-supported (45)Ca uptake by SR were impaired in stunned myocardium (41.3+/-13.5 vs. 73.0+/-15.6 nmol/min/mg protein, p=0.03). The ability of SR calcium ATPase to sequester cytosolic calcium is impaired in stunned myocardium. This is a potential mechanism underlying contractile dysfunction.
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