Diabetic cardiomyopathy: ongoing controversies in 2012

Determining the role of NT-proBNP levels in diabetic patients with heart failure: A study from North India

BACKGROUND

Diabetic patients are at higher risk of cardiovascular morbidity and mortality. NT-proBNP levels measurements are useful for the assessment of risk in heart failure patients in emergency condition and give the faster result. Further, it also offers lower cost and unnecessary hospitalization and follow-up cost. The studies have shown that NT-proBNP levels are a direct predictor of outcome risk in diabetic patients with heart failure. The objective of this research was to study the role of NT-proBNP levels to determine the severity of heart failure in diabetic patients.

MATERIALS AND METHODS

In this study 150 patients diagnosed with symptomatic heart failure admitted to the emergency department of a tertiary care center from January 2021 to January 2022 have been included in Saraswati Institute Of Medical Sciences, Hapur, India. N-terminal pro-B-type natriuretic peptide (NT-Pro-BNP) levels were measured using an automated analyzer ranging between 60 and 3000 pg/ml. According to the European society of cardiology (ESC) guidelines, it has been defined as NT-Pro-BNP level above 125 pg/ml indicates a high possibility of heart failure and NT-Pro-BNP level below 125 pg/ml excludes the high possibility of heart failure. All the patients underwent an echocardiographic study and ejection fraction was calculated and recorded.

RESULTS

In diabetic patients ejection fraction was significantly lower in diabetic patients: 47.15 ± 8.75% vs. 43.24 ± 9.54%, P = 0.002). We have observed statistically significant lower HDL values (40.10 ± vs. 35.94 mg/dL, P = 0.0004), however, significant higher triglycerides values were found (101.43 ± 41.7 mg/dL vs. 151.37 ± 78.85, P = 0.001). No significant difference was observed in LDL level (97.8 ± 31.23 vs. 92.35 ± 314.2, P ≥ 0.05) and total cholesterol level (161.49 ± 41.38 vs. 159.97 ± 41.12, P ≥ 0.05).

CONCLUSION

We concluded that the measurement of NT-proBNP in heart failure and diabetic patients could be an economic marker for the evaluation of morbidity and mortality, facilitating better management and follow-up.

Premature ventricular complex site of origin and ablation outcomes in patients with diabetes mellitus

BACKGROUND

Premature ventricular complexes (PVCs) are frequent in patients with diabetes mellitus (DM). Still, the PVCs characteristics as well as the outcomes after catheter ablation in this population remain unknown. Aim of the study was to describe principal features of PVCs ablated in a wide DM-patients cohort and report postablation clinical outcomes in the follow-up of patients with DM and left ventricular dysfunction.

METHODS

From April 2012 to April 2020 data of 544 patients (315 [58%] men, 55±16 y), consecutive patients submitted for PVC ablation, were prospectively collected. Patients with left ventricle (LV) systolic disfunction (LVEF<50%) were included in a prospective protocol and followed at 6 and 12 months, and annually thereafter. Baseline characteristic as well ablation outcomes were analyzed based on the presence of DM.

RESULTS

Sixty (11%) patients had DM. Patients with DM more frequently had a PVC's site of origin (SOO) in the LV (45 [75%] vs. 229 [48%], P<0.001). The most frequent PVC's SOO in DM patients was the LV outflow tract (OT) (35 [58%] patients: 12 aortic cusps; 12 LV summit; 11 in the myocardium immediately inferior to the valvular plane). Fifty-five (92%) patients with DM had an acute successful ablation, without differences compared with patients without DM (55 [92%] vs. 437 [90%], P=0.9). Twenty-tree (38%) DM-patients had LV dysfunction at the ablation time. In these patients, mean PVC burden decreased from 26±11% at baseline to 4±5% (P<0.001); LVEF increased from 36±8% to 42±11% (P<0.01) and NYHA class improved from 2.2±0.6 to 1.8+0.5 (P<0.01), after a mean follow-up of 37±14 months.

CONCLUSIONS

Patients with DM frequently have PVC with a LV-SOO, being the LVOT the most frequent SOO in this population. Among DM patients with LV dysfunction, ablation persistently and significantly reduce the PVC burden improving functional status. Patients with DM have lower benefit in terms of LV function recovery after ablation compared with non-diabetic patients.

Diabetic cardiomyopathy: Clinical phenotype and practice

Diabetic cardiomyopathy (DCM) is a pathophysiological condition of cardiac structure and function changes in diabetic patients without coronary artery disease, hypertension, and other types of heart diseases. DCM is not uncommon in people with diabetes, which increases the risk of heart failure. However, the treatment is scarce, and the prognosis is poor. Since 1972, one clinical study after another on DCM has been conducted. However, the complex phenotype of DCM still has not been fully revealed. This dilemma hinders the pace of understanding the essence of DCM and makes it difficult to carry out penetrating clinical or basic research. This review summarizes the literature on DCM over the last 40 years and discusses the overall perspective of DCM, phase of progression, potential clinical indicators, diagnostic and screening criteria, and related randomized controlled trials to understand DCM better.

Diabetic Cardiomyopathy as a Clinical Entity: Is It a Myth?

Dilated cardiomyopathy (DCM) is a common form of cardiomyopathy that affects the cardiac muscle. It is a life-threatening condition that causes heart failure as it decreases the myocardial ability to pump sufficient blood throughout the body. Numerous causes trigger DCM without pathophysiology; however, the key concept is a decrease in the systolic function of either the left ventricle or of both the left and right ventricles. Long-term diabetes plays an important role in the pathogenesis of DCM in the form of diabetic cardiomyopathy. Diabetic cardiomyopathy is a non-ischemic form of DCM, which is associated with diabetes. It is unrelated to atherosclerosis and hypertension. The PubMed and Google Scholar databases were used to identify the relevant studies related to diabetes and DCM. We found that diabetes was associated with cardiac muscle injury by activating the renin-angiotensin-aldosterone system, myocardial inflammation, and fibrosis. Based on the available data, we concluded that there is strong evidence to support the interrelation of DCM and diabetes.

Reduced Exercise Capacity in Diabetes Mellitus Is Not Associated with Impaired Deformation or Twist

BACKGROUND

Exercise capacity is frequently reduced in people with diabetes mellitus (DM) and may be due to subclinical cardiac dysfunction. Speckle-tracking echocardiography is now widely available; however, the clinical utility and significance of left ventricular (LV) strain and twist parameters remain uncertain. We hypothesized that LV strain and twist would be reduced in DM subjects during exercise.

METHODS

Adults with type 1 or type 2 DM and age- and sex-matched controls performed cardiopulmonary exercise testing (VO₂ peak) and supine bicycle exercise echocardiography. Detailed echocardiographic assessment of biventricular function was performed at baseline and repeated during incremental exercise to maximal intensity.

RESULTS

Of the 60 participants completing the study protocol, 51 (34 DM, 17 controls; mean age, 42 ± 13 years; 69% male; DM duration, 16 ± 10 years) had sufficient image quality to assess LV deformation and twist mechanics at rest. Of these, 38 (25 DM, 13 controls) were able to be assessed immediately after exercise. Baseline LV systolic and diastolic function using standard echocardiography measurements were similar between groups. Resting LV global longitudinal strain, twist, twist rate and untwist rate, and the corresponding peak exercise and reserve measures did not differ significantly. As compared with the control subjects, exercise capacity was reduced in the DM cohort (VO₂ peak 33 ± 10 vs 41 ± 12 mL/minute/kg; P = .02); however, no correlation was observed between VO₂ peak and LV twist reserve (R = 0.28, P = .09), LV twist rate reserve (R = 0.14, P = .39), or LV untwist rate reserve (R = 0.24, P = .14).

CONCLUSIONS

Despite reduced VO₂ peak, LV twist mechanics at rest and after maximal intensity exercise did not differ significantly in a cohort of asymptomatic DM subjects with normal resting LV systolic and diastolic function compared with age- and sex-matched controls. This would suggest that exercise capacity can be reduced in the absence of subclinical cardiac dysfunction and that noncardiac factors should be considered as alternative explanations.

Exercise capacity in diabetes mellitus is predicted by activity status and cardiac size rather than cardiac function: a case control study

Background

The reasons for reduced exercise capacity in diabetes mellitus (DM) remains incompletely understood, although diastolic dysfunction and diabetic cardiomyopathy are often favored explanations. However, there is a paucity of literature detailing cardiac function and reserve during incremental exercise to evaluate its significance and contribution. We sought to determine associations between comprehensive measures of cardiac function during exercise and maximal oxygen consumption (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}O_{2}$$\end{document}V˙O2peak), with the hypothesis that the reduction in exercise capacity and cardiac function would be associated with co-morbidities and sedentary behavior rather than diabetes itself.

Methods

This case–control study involved 60 subjects [20 with type 1 DM (T1DM), 20 T2DM, and 10 healthy controls age/sex-matched to each diabetes subtype] performing cardiopulmonary exercise testing and bicycle ergometer echocardiography studies. Measures of biventricular function were assessed during incremental exercise to maximal intensity.

Results

T2DM subjects were middle-aged (52 ± 11 years) with a mean T2DM diagnosis of 12 ± 7 years and modest glycemic control (HbA_1c 57 ± 12 mmol/mol). T1DM participants were younger (35 ± 8 years), with a 19 ± 10 year history of T1DM and suboptimal glycemic control (HbA_1c 65 ± 16 mmol/mol). Participants with T2DM were heavier than their controls (body mass index 29.3 ± 3.4 kg/m² vs. 24.7 ± 2.9, P = 0.001), performed less exercise (10 ± 12 vs. 28 ± 30 MET hours/week, P = 0.031) and had lower exercise capacity (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}O_{2}$$\end{document}V˙O2peak = 26 ± 6 vs. 38 ± 8 ml/min/kg, P < 0.0001). These differences were not associated with biventricular systolic or left ventricular (LV) diastolic dysfunction at rest or during exercise. There was no difference in weight, exercise participation or \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}O_{2}$$\end{document}V˙O2peak in T1DM subjects as compared to their controls. After accounting for age, sex and body surface area in a multivariate analysis, significant positive predictors of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}O_{2}$$\end{document}V˙O2peak were cardiac size (LV end-diastolic volume, LVEDV) and estimated MET-hours, while T2DM was a negative predictor. These combined factors accounted for 80% of the variance in \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}O_{2}$$\end{document}V˙O2peak (P < 0.0001).

Conclusions

Exercise capacity is reduced in T2DM subjects relative to matched controls, whereas exercise capacity is preserved in T1DM. There was no evidence of sub-clinical cardiac dysfunction but, rather, there was an association between impaired exercise capacity, small LV volumes and sedentary behavior.

Heart failure and inflammation-related biomarkers as predictors of new-onset diabetes in the general population

BACKGROUND

There is a strong reciprocal relationship between heart failure (HF) and diabetes mellitus (DM). Shared pathophysiological mechanisms might be a possible explanation. Therefore, we hypothesised that biomarkers linked to HF would also predict new-onset type 2 DM in the general population.

METHODS AND RESULTS

We utilized the Prevention of Vascular and Renal End-stage Disease (PREVEND) cohort (mean age 48.9years, 51% female) to study the relationship between HF and DM in 7953 participants free of baseline HF and DM. Multiple HF-related, inflammation-related and renal function-related biomarkers were evaluated regarding their predictive utility in new-onset DM. Incidence of DM in participants who developed HF was 11.8%, versus 5.4% in those who had not developed HF (p<0.001). Incidence of HF in participants who developed DM was 8.5%, versus 3.8% in those who had not developed DM (p<0.001). Classical HF biomarkers, NT-proBNP and hs-TnT were not associated with an increased risk for new-onset DM. However, inflammatory biomarkers hs-CRP [hazard ratio (HR) 1.16, (95% CI 1.05 to 1.29), p=0.005], procalcitonin [HR 1.34, (95% CI 1.07 to 1.69), p=0.012] and PAI-1 [HR 1.55, (95% CI 1.37 to 1.75), p<0.001] remained significantly associated with new-onset DM, even after multivariable adjustment for established predictors of DM.

CONCLUSIONS

Although HF and DM have a strong correlation with each other, systemic biomarkers that predict HF do not have a predictive value in new-onset DM. This suggests that other, indirect, pathophysiological mechanisms related to inflammation may explain their strong relation.

Do age, diabetes and left ventricular function affect the outcomes of ischemic mitral valve repair?

INTRODUCTION

It is well documented that older age, chronic concomitant diseases (such as diabetes mellitus, chronic obstructive lung disease, etc.), and poor left ventricular function can increase the postoperative complication rate and worsen the general outcomes of coronary artery bypass (CABG) and concomitant repair of ischemic mitral regurgitation (MR).

MATERIAL AND METHODS

Retrospective data of 394 patients after CABG and mitral valve (MV) repair (mainly annuloplasty) were analyzed. Patients were grouped according to age, diabetes mellitus (DM), and left ventricular ejection fraction (LVEF). Echocardiography data, the rate of postoperative complications (cardiogenic shock, preoperative myocardial infarction, bleeding from the gastrointestinal tract, cognitive disorders, stroke, sepsis, deep wound infection), and early and late mortality were compared between paired groups.

RESULTS

There were no differences between age groups in reverse positive remodeling of LV. A significantly higher incidence of sepsis and deep wound infection in younger patients was observed. Patients with DM had no change in the pre-postoperative NYHA class and a higher rate of perioperative MI (10.3% vs. 3.1% respectively, p < 0.05) in comparison to patients with no DM. In all LVEF groups, MR was significantly decreased, but reverse positive remodeling of LV was pronounced only in those with "poor" and "moderately lowered" LVEF. Postoperative complications did not differ among these three groups.

CONCLUSIONS

Elderly age, concomitant DM and lowered LVEF do not influence either early or late mortality, including early postoperative outcomes after MV repair for ischemic MR following CABG. Concomitant DM increases the rate of perioperative MI and impairs reverse remodeling of LV.

Profiling of cardiac β-adrenoceptor subtypes in the cardiac left ventricle of rats with metabolic syndrome: Comparison with streptozotocin-induced diabetic rats

Little is known about metabolic syndrome (MetS)-associated cardiomyopathy, especially in relation to the role and contribution of beta-adrenoceptor (β-AR) subtypes. Therefore, we examined the roles of β-AR subtypes in the cardiac function of rats with MetS (MetS group) and compared it with that of rats with streptozotocin (STZ)-induced diabetes (STZ group). Compared with the normal control rats, the protein levels of cardiac β1- and β2-AR in the MetS group were significantly decreased and with no changes in their mRNA levels, whereas the protein levels of β3-AR were similar to those of the controls. However, as shown previously, the protein levels of cardiac β1- and β2-AR in the STZ group were decreased, whereas the β3-AR levels were significantly increased by comparison with the controls. Additionally, the mRNA levels of β2- and β3-AR were increased, but β1-AR mRNA was decreased in the STZ group. Furthermore, left ventricular developed pressure responses to β3-AR agonist BRL37344 were increased in the STZ group but not in the MetS group, whereas for both groups, the responses to noradrenaline were not different from those of the controls. However, the response to stimulation with high concentrations of fenoterol was depressed in the MetS group, compared with the controls, but not in the STZ group. Consequently, our data suggest that the contribution of the β-AR system to cardiac dysfunction in the rats with MetS is not the same as that in the STZ group, although they have similar cardiac dysfunction with similar ultrastructural changes to the myocardium.

Targeting caveolin-3 for the treatment of diabetic cardiomyopathy

Diabetes is a global health problem with more than 550 million people predicted to be diabetic by 2030. A major complication of diabetes is cardiovascular disease, which accounts for over two-thirds of mortality and morbidity in diabetic patients. This increased risk has led to the definition of a diabetic cardiomyopathy phenotype characterised by early left ventricular dysfunction with normal ejection fraction. Here we review the aetiology of diabetic cardiomyopathy and explore the involvement of the protein caveolin-3 (Cav3). Cav3 forms part of a complex mechanism regulating insulin signalling and glucose uptake, processes that are impaired in diabetes. Further, Cav3 is key for stabilisation and trafficking of cardiac ion channels to the plasma membrane and so contributes to the cardiac action potential shape and duration. In addition, Cav3 has direct and indirect interactions with proteins involved in excitation-contraction coupling and so has the potential to influence cardiac contractility. Significantly, both impaired contractility and rhythm disturbances are hallmarks of diabetic cardiomyopathy. We review here how changes to Cav3 expression levels and altered relationships with interacting partners may be contributory factors to several of the pathological features identified in diabetic cardiomyopathy. Finally, the review concludes by considering ways in which levels of Cav3 may be manipulated in order to develop novel therapeutic approaches for treating diabetic cardiomyopathy.

Cardiac structure and function across the glycemic spectrum in elderly men and women free of prevalent heart disease: the Atherosclerosis Risk In the Community study

BACKGROUND

Individuals with diabetes mellitus and pre-diabetes mellitus are at particularly high risk of incident heart failure or death, even after accounting for known confounders. Nevertheless, the extent of impairments in cardiac structure and function in elderly individuals with diabetes mellitus and pre-diabetes mellitus is not well known. We aimed to assess the relationship between echocardiographic measures of cardiac structure and function and dysglycemia.

METHODS AND RESULTS

We assessed measures of cardiac structure and function in 4419 participants without prevalent coronary heart disease or heart failure who attended the Atherosclerosis Risk In the Community (ARIC) visit 5 examination (2011-2013) and underwent transthoracic echocardiography (age, 75±6 years; 61% women, 23% black). Subjects were grouped across the dysglycemia spectrum as normal (39%), pre-diabetes mellitus (31%), or diabetes mellitus (30%) based on medical history, antidiabetic medication use, and glycated hemoglobin levels. Glycemic status was related to measures of cardiac structure and function. Worsening dysglycemia was associated with increased left ventricular mass, worse diastolic function, and subtle reduction in left ventricular systolic function (P≤0.01 for all). For every 1% higher glycated hemoglobin, left ventricular mass was higher by 3.0 g (95% confidence interval, 1.5-4.6 g), E/E' by 0.5 (95% confidence interval, 0.4-0.7), and global longitudinal strain by 0.3% (95% confidence interval, 0.2-0.4) in multivariable analyses.

CONCLUSIONS

In a large contemporary biracial cohort of elderly subjects without prevalent cardiovascular disease or heart failure, dysglycemia was associated with subtle and subclinical alterations of cardiac structure, and left ventricular systolic and diastolic function. It remains unclear whether these are sufficient to explain the heightened risk of heart failure in individuals with diabetes mellitus.

Effect and mechanisms of zinc supplementation in protecting against diabetic cardiomyopathy in a rat model of type 2 diabetes

Diabetic cardiomyopathy is a prominent cause of heart failure in patients with diabetes mellitus. Currently, there is no specific treatment for diabetic cardiomyopathy. This study aimed to investigate the effect and underlying mechanisms of Zinc (Zn) supplementation in the protection against diabetic cardiomyopathy in a rat model of type 2 diabetes mellitus (T2DM). T2DM-like lesions in male Wistar rats were induced by introducing the high-fat diet and by administration of streptozocin (STZ). After STZ induction, animals with fasting plasma glucose level ≥16.7 mM were considered as diabetic, and randomly assigned to the group receiving physiological saline (control) or ZnSO4 for 56 days. On days 0, 7, 28 and 56 of treatment, animals were weighed, and their blood samples were analyzed. On day 56, hemodynamic assessment was performed right before the sacrifice of animals. Cardiac tissue specimens were collected and subjected to pathologic assessment, metallothionein (MT) concentration measurement and Western blot analysis of microtubule-associated protein light chain 3 (LC3), the marker of autophagy, and glucose-regulated protein-78 (GRP78), an oxidative stress marker. High-fat diet feeding followed by STZ administration resulted in weight loss, hyperglycemia, polydipsia, polyphagia, hemodynamic anomalies and a significant increase in the myocardial content of LC3 and GRP78 proteins, but not in MT protein. Zn supplementation effectively attenuated all these aberrations induced by high-fat diet and STZ. These findings suggest that Zn might be a protective factor in diabetic cardiomyopathy, acting in two ways: at least partially, through inhibiting autophagy and by endoplasmic reticulum stress.

[Heart failure. Cardiovascular autonomic neuropathy in patients with diabetes mellitus]

In spite of new therapy options the life expectancy of patients with diabetes mellitus is clearly reduced compared to the average population. In addition to coronary heart disease and diabetic cardiomyopathy, cardiac autonomic neuropathy (CAN) is also a factor in patients with diabetes mellitus. The CAN is an impairment of cardiovascular control. A reduced variability of heart rate up to the point of a fixed heart rate are symptoms of CAN. In addition symptomatic hypotension, a reduced left ventricular ejection fraction, cardiac arrhythmia and sudden cardiac death are also signs of CAN. Prevalence rates of CAN increase with age and are approximately 38 % in patients 40-70 years old with diabetes mellitus type 1 and 44 % in patients with diabetes mellitus type 2. The disease is usually documented using miscellaneous cardiovascular autonomic tests so that therapy can be started as soon as possible.

Hyperglycemia has a greater impact on left ventricle function in South Asians than in Europeans

OBJECTIVE Diabetes is associated with left ventricular (LV) diastolic and systolic dysfunction. South Asians may be at particular risk of developing LV dysfunction owing to a high prevalence of diabetes. We investigated the role of diabetes and hyperglycemia in LV dysfunction in a community-based cohort of older South Asians and white Europeans. RESEARCH DESIGN AND METHODS Conventional and Doppler echocardiography was performed in 999 participants (542 Europeans and 457 South Asians aged 58-86 years) in a population-based study. Anthropometry, fasting bloods, coronary artery calcification scoring, blood pressure, and renal function were measured. RESULTS Diabetes and hyperglycemia across the spectrum of HbA1c had a greater adverse effect on LV function in South Asians than Europeans (N-terminal-probrain natriuretic peptide β ± SE 0.09 ± 0.04, P = 0.01, vs. -0.04 ± 0.05, P = 0.4, P for HbA1c/ethnicity interaction 0.02), diastolic function (E/e' 0.69 ± 0.12, P < 0.0001, vs. 0.09 ± 0.2, P = 0.6, P for interaction 0.005), and systolic function (s' -0.11 ± 0.06, P = 0.04, vs. 0.14 ± 0.09, P = 0.1, P for interaction 0.2). Multivariable adjustment for hypertension, microvascular disease, LV mass, coronary disease, and dyslipidemia only partially accounted for the ethnic differences. Adverse LV function in diabetic South Asians could not be accounted for by poorer glycemic control or longer diabetes duration. CONCLUSIONS Diabetes and hyperglycemia have a greater adverse effect on LV function in South Asians than Europeans, incompletely explained by adverse risk factors. South Asians may require earlier and more aggressive treatment of their cardiometabolic risk factors to reduce risks of LV dysfunction.

Assessment and management of left ventricular hypertrophy in Type 2 diabetes patients with high blood pressure

Diabetes is associated with left ventricular hypertrophy (LVH). This article reviews the assessment and management of LVH in Type 2 diabetic patients and the available evidence on blood-pressure management in these patients in order to reduce LVH. The best treatment of LVH starts with early identification and rapid implementation of adequate treatment, especially in populations at higher risk. Angiotensin II receptor antagonists and angiotensin-converting enzyme inhibitors should be the first-line therapy, because they are proven to be the most effective in reducing LVH in Type 2 diabetic patients. In patients where angiotensin II receptor antagonists and angiotensin-converting enzyme inhibitors are contraindicated or not tolerated, calcium-channel blockers should be the second option.

Depressed calcium-handling proteins due to endoplasmic reticulum stress and apoptosis in the diabetic heart are attenuated by argirein

Diabetic cardiomyopathy (DC) is a unique disease frequently complicated to diabetes mellitus, manifesting endoplasmic reticulum (ER) stress and depressed calcium-handling proteins. We hypothesized that the abnormal FKBP12.6, SERCA2a, and CASQ2 are consequent to ER stress and apoptosis that are likely due to an entity of inflammation. These abnormalities may be attributed to reactive oxygen species genesis from activated NADPH oxidase which could respond to argirein (AR) through its anti-inflammatory activity. Sprague Dawley rats were randomly divided into six groups. Except the normal group, rats were injected with streptozotocin (STZ; 60 mg/kg, i.p.) once. During weeks 5 to 8 following STZ injection, rats were treated (in milligrams per kilogram per day, i.g.) with aminoguanidine (AMG, 100; an inducible nitric oxide synthase and AGEs inhibitor) or three doses of AR (50, 100, and 200). FKBP12.6, SERCA2a, and CASQ2 and ER stress chaperones Bip and PERK and apoptotic molecules were monitored in vivo and in vitro. Impaired cardiac performance and downregulated FKBP12.6, SERCA2a, and CASQ2 were significant in DC in vivo, and abnormal calcium-handling proteins were also found in high-glucose-incubated myocytes in vitro. ER stress manifested by upregulated Bip and PERK was predominant in association with DNA ladder and upregulated Bax and downregulated BCL-2 in vivo and in vitro. AR is effective to attenuate these abnormalities compared to AMG. Diabetic myocardium has inflammatory entity expressed as ER stress contributing to downregulated calcium-handling proteins. AR has potential in managing DC through attenuating depressed calcium-handling proteins, activated ER stress, and apoptosis in the myocardium.