Glycogen Phosphorylase BB Research Articles

Glycogen Phosphorylase-BB and Corrected QT Interval in Early Prediction of Cardiotoxicity in Patients with Acute Aluminum Phosphide Poisoning

Abstract Background Aluminum phosphide (ALP) is a highly toxic pesticide that cause multi-organ affection. Cardiovascular affection accounts for high mortality. So, early prediction of myocardial injury and arrhythmias are important in the management. Aim This study aimed at investigating the role of Glycogen phosphorylase BB (GPBB) and corrected QT interval (QTc) in early prediction of ALP induced cardiotoxicity. Methods and Results The current study was a prospective study carried at Poison Control Center of Ain Shams University on thirty ALP intoxicated adults and thirty age and sex matched healthy controls. Patients were subjected to history taking, clinical examination, grading of severity according to Poison Severity Score (PSS) and on admission investigations including electrocardiogram (ECG) and GPBB. Outcome was also recorded. The results revealed that GPBB was higher in intoxicated patients than controls and there was significant difference among outcome groups. GPBB also was able to detect cardiotoxicity and predict mortality. QTc interval was longer in intoxicated patients than healthy controls and was able to predict occurrence of arrhythmias. Conclusion It was concluded that GPBB is a promising biomarker to predict myocardial injury following aluminum phosphide intoxication and on admission corrected QT interval is simple bed side tool to predict arrhythmias. Recommendations The present study recommended the use of GPBB and corrected QT interval as useful markers for prediction of ALP cardiotoxicity.

Electroacupuncture ameliorates cardiac dysfunction in myocardial ischemia model rats: a potential role of the hypothalamic-pituitary-adrenal axis.

To verify the hypothesis that electroacupuncture inhibits the hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis regulating the expression of glial fibrillary acidic protein (GFAP) in the hippocampus of acute myocardial ischemia (AMI) rats. Sixty-six healthy male Sprague-Dawley rats were randomly divided into five groups: Sham, AMI (Model), electroacupuncture at Shenmen (HT7)-Tongli (HT5) segment (EA), non-acupoint electroacupuncture (Control), and Model + corticosterone (Model + CORT). AMI was induced occlusion of the left anterior descending coronary artery, followed by 3 d of electroacupuncture at Shenmen (HT7)-Tongli (HT5) segment. In the Control group, electroacupuncture was applied at points lying 5 and 10 mm from the base of the tail. The AMI + CORT group was injected with CORT (20 mg/kg) in saline. Hemorheology, electrocardiography (ECG), hematoxylin and eosin staining, and expression of glycogen phosphorylase BB (GPBB) and heart-type fatty acid-binding protein (H-FABP) were used to assess cardiac function. The effects of adrenocorticotropic hormone (ACTH) and CORT were evaluated by enzyme-linked immunosorbent assay. Protein expression in the Sham and Model groups were screened by tandem mass tag-based quantitative proteomics analysis. Protein expression was evaluated by Western blotting (vimentin and GFAP) and immunofluorescence staining (GFAP). Compared with the Sham group, the hemorheology indicators, heart rate, ECG-ST segment elevation, and GPBB and H-FABP levels were higher in Model rats. The EA group showed reductions in these indicators compared with the Model group. Similarly, in Model rats, the expression of ACTH and CORT were significantly increased compared with the Sham group. The EA group also showed reduced expression of ACTH and CORT. Importantly, proteomics analysis showed that vimentin was differentially expressed in Model rats. Compared with the Sham group, vimentin and GFAP expression in the hippocampus was increased in the Model group but decreased in the AMI + EA group. Additionally, intraperitoneal injection of CORT aggravated the expression of GPBB, H-FABP and GFAP. Our results suggested that electroacupuncture may protect against cardiac injury induced by AMI through regulation of HPA axis hyperactivity, and that hippocampal GFAP may play an important role in the regulation.

Diagnostic accuracy of glycogen phosphorylase BB for myocardial infarction: A systematic review and meta-analysis.

PurposeWe tried to investigate the diagnostic accuracy of glycogen phosphorylase BB as a cardiac marker for myocardial infarction.MethodsWe searched through different electronic databases (PubMed, Google‐scholar, Embase, and Cochrane Library) to locate relevant articles. Studies, with sufficient data to reconstruct a 2 × 2 contingency table, met our inclusion criteria were included. Three reviewers independently screened the articles. Discrepancies were resolved by other reviewers. Unpublished data were requested from the authors of the study via email. Subsequently, data extraction was done using a standardized form and quality assessment of studies using the QUADAS‐2 tool. Meta‐analysis was done using a bivariate model using R software.ResultsFourteen studies were selected for the final evaluation, which yielded the summary points: pooled sensitivity 87.77% (77.52%–93.72%, I2 = 86%), pooled specificity 88.45% (75.59%–94.99%, I2 = 88%), pooled DOR 49.37(14.53–167.72, I2 = 89%), and AUC of SROC was 0.923. The lambda value of the HSROC curve was 3.670. The Fagan plot showed that GPBB increases the pretest probability of myocardial infarction from 46% to 81% when positive, and it lowers the same probability to 12% when negative.ConclusionWith these results, we can conclude that GPBB has modest accuracy in screening myocardial infarction, but the limitations of the study warrant further high‐quality studies to confirm its usefulness in predicting myocardial infarction (MI).

Evaluation of Glycogen Phosphorylase BB (GPBB) Level in Serum as Marker in Diagnosis of Acute Ischemic Stroke

Objective: We aimed to investigate whether Serum levels of glycogen phosphorylase BB (GPBB) isoformcould be used as a potential diagnostic biomarker in Acute Ischemic Stroke (AIS) patients or not.Materials and methods : glycogen phosphorylase BB were prospectively evaluated in 40 patients agedbetween 40 to 70 y who were admitted within 24 h of the onset of AIS. The control group included 40healthy volunteers of similar age without any disease.Results: There is a significant elevation in the level of GPBB in ischemic stroke group and compared withcontrol group. For Control, the observations of GPBB had an Min = 4.91 For Stroke, the observations ofGPBB had an Min = 15.32There was a significant positive correlation between stoke and Glycogen phosphorylase (rpb = 0.7473,p< .001). The correlation coefficient between Stroke and Glycogen phosphorylase was 0.7473 indicatinga large effect size. This indicates that moving from the Not having to having Stroke is associated withan increase in Glycogen phosphorylase. Therefore, Stroke tends to be associated with higher values ofGlycogen phosphorylaseConclusions: 1-This study shows there is significant elevation in enzyme level of glycogen phosphorylaseBB (GPBB) in ischemic stroke group and compared with control group.

Serum glycogen phosphorylase BB (GPBB) level and Prolidase activity as markers in diagnosis of ischemic stroke

Serum glycogen phosphorylase BB (GPBB) level and Prolidase activity as markers in diagnosis of ischemic stroke

Role of Glycogen Phosphorylase in Prediction of Cardiotoxicity Associated with Acute Carbon Monoxide Poisoning

Introduction: Carbon monoxide (CO) poisoning is a leading cause of death from intoxication. The heart is extremely susceptible to CO-induced hypoxia due to its high oxygen demand. Cardiovascular involvement in CO poisoning could be clinically occult and undiagnosed due to lack of overt symptoms or specific electrocardiogram (ECG) changes. There is an emerging need for early and specific markers for myocardial hypoxia. One potential candidate is the glycogen phosphorylase BB isoenzyme (GPBB). Aim of the study: The study was planned to assess the role of glycogen phosphorylase in early prediction of myocardial toxicity due to CO poisoning. Methods: This prospective study included 2 groups; Control group and Patient group. Control group included 15 non-smokers healthy adults aged between 20 and 35 years old selected from patients’companions presented to Zagazig University Hospitals. Patient group included 30 adults aged 20-35 years old with history of CO exposure within 6 hrs. They were sub- divided into mild & moderate CO poisoning groups according to COHB% & clinical manifestations. The study was performed during the period between January 2015 to April 2016. All the subjects enrolled in the study were subjected to clinical examination, ECG, echocardiogram (Echo), cardiac troponin I (cTn-I) and GPBB assessment. Results: There was a significant increase in heart rate between patient and control groups. Also, a significant increase in GPBB was found between patient and control groups and this was associated with a significant decrease of ejection fraction evaluated by Echo in moderate CO poisoning group when compared with control group. No significant differences were found as regard serum cTn-1 level or ECG findings between patient and control groups. Conclusion: GPBB can be used as an early predictor of CO-induced myocardial ischemia which in turn may modify management plan to avoid later sequelae affecting ventricular function.

New biomarker for acute ischaemic stroke: plasma glycogen phosphorylase isoenzyme BB

BackgroundGlycogen phosphorylase is the key enzyme that breaks down glycogen to yield glucose-1-phosphate in order to restore depleted energy stores during cerebral ischaemia. We sought to determine whether plasma levels...

Heart-type fatty acid-binding protein (H-FABP) and highly sensitive troponin T (hsTnT) as markers of myocardial injury and cardiovascular events in elective percutaneous coronary intervention (PCI).

Type 4a myocardial infarction (MI) occurs when myocardial injury is combined with either symptoms suggestive of myocardial ischaemia, new left bundle branch block, angiographic loss of patency of a major artery or imaging suggestive of new loss of myocardium. Myocardial injury is defined as a rise of >5 x 99th upper reference limit (URL) of 14 ng/l (i.e. >70 ng/l) for highly sensitive troponin T (hsTnT) at 6 h if hsTnT was normal at baseline or >20% rise from 0 to 6 h if hsTnT was >14 ng/l at baseline. To assess the prognostic value of biomarkers of myocardial injury following elective percutaneous coronary intervention (PCI). A cohort of 209 patients were included of whom 144 (68.9%) were male, mean age was 68.8 years, 28 (13.4%) were smokers, 31 (14.8%) were diabetic, 199 (95.2%) had hypercholesterolaemia and 138 (66.0%) had hypertension. We evaluated hsTnT, heart-type fatty acid-binding protein (H-FABP), troponin I (TnI), creatine kinase MB type (CKMB), myoglobin, glycogen phosphorylase BB (GPBB) and carbonic anhydrase III (CA III) at 0, 4, 6 and 24 h following elective PCI. Patients were followed up at 1 year to assess for major adverse clinical events (MACE). Myocardial injury was observed in 37 (17.7%) patients. Median hsTnT/H-FABP at 4 h were most predictive. MACE was noted in 6 (2.9%) patients, 3 had type 4a MI post PCI, P = 0.036. Median 4 h hsTnT/H-FABP were most predictive of myocardial injury following PCI. H-FABP and hsTnT were predictive of MACE.

Glycogen Phosphorylase BB: A more Sensitive and Specific Marker than Other Cardiac Markers for Early Diagnosis of Acute Myocardial Infarction.

Cardiac markers are used to evaluate functions of heart. However, there are no satisfactory cardiac biomarkers for the diagnosis of acute myocardial infarction (AMI) within 4h of onset of chest pain. Among novel cardiac markers, glycogen phosphorylase BB (GPBB) is of particular interest as it is increased in the early hours after AMI. The present study was conducted with the objective to find out the sensitivity and specificity of GPBB over other cardiac markers i.e. myoglobin and CKMB in patients of AMI within 4h after the onset of chest pain. The study includes 100 AMI patients and 100 normal healthy individuals as controls. In all the cases and controls, serum GPBB and myoglobin concentrations were measured by ELISA where as CK-MB was measured by diagnostic kit supplied by ERBA. The sensitivity and specificity of glycogen phosphorylase BB (GPBB) were greater than CK-MB and myoglobin in patients of AMI within 4h after the onset of chest pain. Hence, glycogen phosphorylase BB (GPBB) can be used as additional biomarker for the early diagnosis of AMI.

Troponins, heat shock proteins and glycogen phosphorylase BB in umbilical cord blood of complicated pregnancies

Purpose of the study: Heat shock proteins (Hsp) are evolutionary conserved molecules with a chaperone role in cell survival. We hypothesized that cord blood concentrations of molecules reflecting fetal cardiac muscle insult, including Hsp, troponins cTnI and cTnT, and glycol-phosphorylase BB (GP-BB) would be elevated in pregnancies complicated by gestational diabetes (GDM) or preeclampsia (PIH) compared to healthy controls.Materials and methods: Pregnant women admitted for delivery at >28 weeks were divided into four groups: healthy patients delivered vaginally (VAG), healthy patients delivered by c-section (CS), patients with PIH, and patients with GDM. Demographics, clinical characteristics, and cord blood concentrations of Hsp, troponins cTnI and cTnT, and GP-BB were compared between groups. Statistical analyses included t-test, Chi square, and Wilcoxon rank sum as appropriate.Results: cTnI concentrations were significantly higher in the PIH group compared to the GDM and VAG groups and they were higher in the CS group compared to the VAG group. Concentrations of Hsp70 were higher in the GDM group compared to the VAG and CS groups. Concentration of GP-BB was higher in the PIH group compared to the VAG group.Conclusions: GP-BB and cTNI are the most sensitive markers for PIH-related fetal myocyte injury as is Hsp70 in pregnancies complicated by GDM.

Comparative status of glycogen phosphorylase BB, myoglobin, and CK-MB for early diagnosis of acute myocardial infarction

Comparative status of glycogen phosphorylase BB, myoglobin, and CK-MB for early diagnosis of acute myocardial infarction

193: Cord blood Troponins and Glycogen phosphorylase BB in pregnancies complicated by gestational diabetes and preeclampsia

193: Cord blood Troponins and Glycogen phosphorylase BB in pregnancies complicated by gestational diabetes and preeclampsia

Cost-Effectiveness of Introducing Point-of-Care Test for Detection of Level of Glycogen Phosphorylase in Early Diagnostic Algorithm of Acute Coronary Syndrome

BackgroundThe detection of specific biomarkers in the early phase of acute coronary syndrome (ACS) is important for the early diagnosis and appropriate management of patients with ACS. ObjectivesTo estimate the cost-effectiveness of introducing a diagnostic point-of-care (POC) test for determining the levels of glycogen phosphorylase BB isoform (GPBB) in a standard diagnostic algorithm for the early diagnosis of ACS within the health system of the Republic of Serbia. MethodsThe probabilistic decision-tree model was constructed for patients with nontraumatic chest pain comparing the use of standard diagnostic procedure, physical examination, and electrocardiogram monitoring with the use of a diagnostic test for the detection of the levels of specific biomarkers. The perspective of the health care services purchaser (the Republic Institute for Health Insurance, Serbia) was used in the model, and only direct costs were taken into account. The time horizon was set at one treatment episode of ACS, and the discount rate was not included because of the short length of the time horizon. ResultsUsing the GPBB POC test in comparison with not using it in the early diagnosis of ACS results in a significant reduction in the cost per treatment episode (10,034.48 ± 7,283.80 Serbian dinar [RSD]), increase in the number of survivors per 1000 treatment episodes (16 ± 18), decrease in the number of hospitalizations per 1000 treatment episodes (104 ± 44), and decrease in the number of performed coronarographies per 1000 treatment episodes (22 ± 19). The costs per hospitalization avoided (incremental cost-effectiveness ratio) were −145,887.57 ± 5,271.54 RSD, and the costs per coronarography avoided were −137,295.68 ± 4,681.05 RSD. ConclusionsIn the circumstances of limited health resources, reducing hospitalizations and decreasing unnecessary treatments and invasive diagnostic procedures by a GPBB POC test could be an effective way to improve the economic status of other Balkan countries with limited health care budgets.

Altered Maternal Plasma Glycogen Phosphorylase Isoenzyme BB as a Biomarker for Preeclampsia and Small for Gestational Age.

To investigate whether maternal plasma glycogen phosphorylase BB (GPBB) levels were altered in early pregnancy and/or at the time of diagnosis of disease in preeclampsia (term and preterm <37 weeks' gestation) or small for gestational age (SGA). We conducted 6 nested case-control studies within the Screening of Pregnancy Endpoint (SCOPE) Ireland cohort. Blood samples from women with preeclampsia or SGA were analyzed both from the time of disease presentation and at 15 and 20 weeks' gestation. These were compared with control samples obtained from SCOPE women with healthy uncomplicated pregnancies matched for age, ethnicity, parity, body mass index, and gestational age. Glycogen phosphorylase BB levels were measured using the Diacordon GPBB enzyme-linked immunosorbent assay (Diagenics, Germany). Glycogen phosphorylase BB levels were higher in women with preeclampsia compared with controls at the time of disease (term preeclampsia median [interquartile range (IQR)]: 22.2 [15.1-39.8] ng/mL vs 16.9 [10.4-19.1] ng/mL; P = .04; N = 14 and preterm preeclampsia median [IQR]: 23.1 [11.2-30.9] ng/mL vs 17.2 [9.8-19.1] ng/mL; P = .04; N = 11) and at 20 weeks' gestation (median [IQR]: 23.0 [15.6-31.4] ng/mL vs 17.0 [13.4-23.6] ng/mL; N = 39; P = .04). Glycogen phosphorylase BB levels were also significantly higher in women with SGA compared with normal controls at the time of disease detection (median [IQR]: 22.7 [12.6-25.5] ng/mL vs 17.0 [9.8-18.0] ng/mL; N = 23; P = .03) but significantly less than controls at 15 weeks' gestation prior to disease detection (median [IQR]: 16.0 [12.1-23.2] ng/mL vs 22.2 [17.0-28.9] ng/mL; N = 25; P = .02). Glycogen phosphorylase BB alone has modest predictive abilities for the development of preeclampsia or SGA. Further research may examine its use in combination with other markers.

Does dexmedetomidine have a cardiac protective effect during non-cardiac surgery? A randomised controlled trial.

This study was designed to determine the effects of dexmedetomidine on perioperative myocardial injury by observing peripheral circulatory changes in response to tracheal intubation and extubation, myocardial enzyme levels, myocardial ischaemia improvements, cardiovascular adverse events and cytokines in patients with coronary heart disease (CHD) undergoing non-cardiac surgery. This study was a prospective, randomized, double-blind trial. Eighty patients having CHD were scheduled for elective hip-replacement surgery and randomly allocated to receive a loading dose of 1 μg/kg dexmedetomidine followed by a 0.2 μg/kg per h infusion (Dex group; n = 40) or normal saline (control group; n = 40). Systolic blood pressure, diastolic blood pressure, mean arterial pressure, heart rate, rate-pressure product and changes in ST-T segment on the electrocardiogram were recorded every 5 min during surgery. Serum creatine kinase-MB (CK-MB), cardiac troponin I (cTnI), glycogen phosphorylase BB (GP-BB), interleukin (IL)-6 and tumour necrosis factor (TNF)-α protein levels were determined preoperatively, at the end of surgery and 12 and 24 h after surgery. The improvement rate of myocardial ischaemia was higher in the Dex than control group (87.5% vs 32.5%, respectively; P < 0.05). In addition, the Dex group had lower serum CK-MB, IL-6, cTnI and GP-BB concentrations than the control group (P < 0.05). There was no significance difference in TNF-α between the two groups (P > 0.05). Dexmedetomidine can reduce myocardial injury and cytokine levels in patients with CHD undergoing non-cardiac surgery.

Glycogen metabolism protects against metabolic insult to preserve carotid body function during glucose deprivation.

The view that the carotid body (CB) type I cells are direct physiological sensors of hypoglycaemia is challenged by the finding that the basal sensory neuronal outflow from the whole organ is unchanged in response to low glucose. The reason for this difference in viewpoint and how the whole CB maintains its metabolic integrity when exposed to low glucose is unknown. Here we show that, in the intact superfused rat CB, basal sensory neuronal activity was sustained during glucose deprivation for 29.1±1.2min, before irreversible failure following a brief period of excitation. Graded increases in the basal discharge induced by reducing the superfusate PO2 led to proportional decreases in the time to the pre-failure excitation during glucose deprivation which was dependent on a complete run-down in glycolysis and a fall in cellular energy status. A similar ability to withstand prolonged glucose deprivation was observed in isolated type I cells. Electron micrographs and immunofluorescence staining of rat CB sections revealed the presence of glycogen granules and the glycogen conversion enzymes glycogen synthase I and glycogen phosphorylase BB, dispersed throughout the type I cell cytoplasm. Furthermore, pharmacological attenuation of glycogenolysis and functional depletion of glycogen both significantly reduced the time to glycolytic run-down by ∼33 and 65%, respectively. These findings suggest that type I cell glycogen metabolism allows for the continuation of glycolysis and the maintenance of CB sensory neuronal output in periods of restricted glucose delivery and this may act as a key protective mechanism for the organ during hypoglycaemia. The ability, or otherwise, to preserve energetic status may thus account for variation in the reported capacity of the CB to sense physiological glucose concentrations and may even underlie its function during pathological states associated with augmented CB discharge.

Evaluation of Cardiac Markers in Children Undergoing Hematopoietic Stem Cell Transplantation.

Early life-threatening cardiotoxicity and cardiac death have been reported after hematopoietic stem cell transplantation (HSCT). The purpose of the current study was to evaluate cardiac toxicity of conventional chemotherapy followed by HSCT with cardiac markers: heart-type fatty acid binding protein (H-FABP), glycogen phosphorylase BB (GPBB), high sensitive C reactive protein (hsCRP) cardiac troponin I, (cTnI), creatine kinase MB (CK-MB mass) and myoglobin. A total of 20 children who underwent HSCT for malignant and non-malignant diseases were included in this study. Blood samples were collected from all patients in 0th, 7th and 21st day for evaluating these cardiac biomarkers. The patients' echocardiography was assessment before and after one-month of HSCT. Serum 21st H-FABP level was significantly higher when compared with the 0th day H-FABP level (P < 0.05) . 7th day hsCRP level was significantly higher than 0th and 21st day levels (P < 0.05). Interestingly, 7th day GPBB level was significantly lower than 0th and 21st day levels (P < 0.05). Myoglobin, CK-MB mass and cTnI biomarkers remained within the reference range in all patients. This study showed that H-FABP and hsCRP both seem to be promising markers for evaluation of cardiotoxicity in HSCT process and probably superior to GPBB, cTnI, CK-MB mass and myoglobin.

Glycogen phosphorylase BB levels are associated with haemodynamic parameters in cirrhotic patients undergoing transjugular intrahepatic portosystemic shunt insertion.

Transjugular intrahepatic portosystemic shunts (TIPS) have become a widely accepted tool in the treatment of patients with symptomatic portal hypertension. The aim of our study was to assess glycogen phosphorylase BB (GPBB) concentration in relation to echocardiographic and haemodynamic parameters in patients before and after TIPS insertion. The study population consisted of 55 patients (38 men and 17 women, age 55.6±8.9 years, range 37-74 years) with liver cirrhosis treated with transjugular portosystemic shunting. GPBB, echocardiographic, and haemodynamic parameters were measured before TIPS insertion and 24 h after the procedure. GPBB concentrations were assessed using the Cardiac Array for Evidence Investigator protein biochip. Correlation between parameters was assessed using the Spearman's coefficient. Serum post-procedural GPBB concentrations were increased in comparison with baseline (5.58 vs. 2.67 μg/L, P<0.001). GPBB concentration after TIPS significantly correlated with baseline systemic vascular resistence (r=0.330; P=0.017) and cardiac index (r=0.313; P=0.025). GPBB concentration measurement may be a useful tool for monitoring myocardial ischemia during a TIPS procedure.

Biomarkers for the early detection of anthracycline-induced cardiotoxicity: current status

Cardiotoxicity is a well-known and potentially serious complication of anticancer therapy. Anthracycline-based chemotherapy represents the greatest risk. Early detection of cardiotoxicity is crucial for applying preventive and supportive therapeutic strategies. Various methods have been recommended for monitoring of cardiotoxicity. In our conditions, echocardiography and electrocardiography are routinely used. However, this approach shows low sensitivity for the early prediction of cardiomyopathy when the possibilities of appropriate management could still improve the patient's outcome. Recently, biomarkers of cardiac injury have been investigated in the assessment of chemotherapy-induced cardiotoxicity. Cardiospecific biomarkers, such as cardiac troponins, show high diagnostic efficacy in the early subclinical phase of the disease before the clinical onset of cardiomyopathy. Increase in their concentrations correlates with disease severity. As for natriuretic peptides, some studies, including ours, have shown promising results. Definitive evidence of their diagnostic and prognostic role in this context is still lacking and natriuretic peptides have not been routinely used for monitoring of cardiotoxicity in clinical practice. Other perspective biomarkers of cardiotoxicity in oncology are under study, especially heart-type fatty acid-binding protein (H-FABP) and glycogen phosphorylase BB (GPBB). Our studies using GPBB have provided encouraging results. However, the available data are limited and their practical use in this context cannot be recommended until their clinical efficacy is clearly defined. This review covers the current status of biomarkers for the early detection of anthracycline-induced cardiotoxicity. The authors present in brief, their own experience with multiple biomarkers in the detection of cardiotoxicity.

Glycogen phosphorylase isoenzyme BB plasma kinetics is not related to myocardial ischemia induced by exercise stress echo test

Glycogen phosphorylase BB (GPBB) is released from cardiac cells during myocyte damage. Previous studies have shown contradictory results regarding the relation of enzyme release and reversible myocardial ischemia. The aim of this study was to determine the plasma kinetics of GPBB as a response to the exercise stress echocardiographic test (ESET), and to define the relationship between myocardial ischemia and enzyme plasma concentrations. We studied 46 consecutive patients undergoing ESET, with recent coronary angiography. In all patients, a submaximal stress echo test according to Bruce protocol was performed. Concentration of GPBB was measured in peripheral blood that was sampled 5 min before and 10, 30 and 60 min after ESET. There was significant increase of GPBB concentration after the test (p=0.021). Significant increase was detected 30 min (34.9% increase, p=0.021) and 60 min (34.5% increase, p=0.016) after ESET. There was no significant effect of myocardial ischemia on GPBB concentrations (p=0.126), and no significant interaction between sampling intervals and myocardial ischemia, suggesting a similar release profile of GPBB in ischemic and non-ischemic conditions (p=0.558). Patients in whom ESET was terminated later (stages 4 or 5 of standard Bruce protocol; n=13) had higher GPBB concentrations than patients who terminated ESET earlier (stages 1, 2 or 3; n=33) (p=0.049). Baseline GPBB concentration was not correlated to any of the patients' demographic, clinical and hemodynamic characteristics. GPBB plasma concentration increases after ESET, and it is not related to inducible myocardial ischemia. However, it seems that GPBB release during ESET might be related to exercise load/duration.