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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: OBJECTIVE, METHODS, RESULTS. Meshes: Analysis of Variance, Biomarkers, Blotting, Western, Calcium-Binding Proteins, Calcium-Transporting ATPases, Case-Control Studies, Coronary Artery Bypass, Echocardiography, Doppler, Female, Humans, Male, Myocardial Infarction, Myocardial Stunning, Predictive Value of Tests, Probability, Prognosis, Reference Values, Sampling Studies, Sarcoplasmic Reticulum Calcium-Transporting ATPases, Sensitivity and Specificity, Severity of Illness Index, Survival Analysis, Tissue Culture Techniques.
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Do suppressed phospholamban levels differentiate irreversibly dysfunctional from hibernating myocardium in humans? Context: We studied whether dysfunction of human hibernating (HIB) and irreversibly dysfunctional myocardium (IRDM) are associated with altered levels of the sarcoplasmatic reticulum calcium handling proteins Ca2+-ATPase (SERCA2a) and its inhibitor phospholamban (PLB). In 12 patients myocardial biopsies were taken during bypass surgery and analysed for contents of these proteins. We classified regions as control, HIB, or IRDM based on echocardiographic studies before and 6 months after surgery. SERCA2a content (mean+/-SEM) was similar to control in HIB and IRDM (2.6 +/- 1.7, 3.8 +/- 2.0, and 3.4 +/- 1.9 units/g non-collagen protein (NCP), p = 0.40). PLB content was similar to control in HIB (2.6 +/- 0.4 and 3.5 +/- 0.5 units/microg NCP) but reduced in IRDM (0.9 +/- 0.2 units/microg NCP, p < 0.05). SERCA2a:PLB ratio, an indicator of SERCA2a activity, did not differ between control and HIB (1.2 +/- 0.3 and 1.4 +/- 0.4 units/microg NCP) but was increased in IRDM (5.1 +/- 1.7 units/microg NCP, p < 0.05).
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Inappropriate SERCA2a activity due to suppressed PLB levels may represent a maladaptive mechanism in chronic ischemic myocardium being causally linked to irreversibility of left ventricular dysfunction. Final Decision: yes