Calcium Handling Proteins Research Articles

Empagliflozin Ameliorates Atrial and Ventricular Remodeling and Arrhythmogenesis in an Overweight Rabbit Model.

Overweight is associated with dysrhythmia and sudden cardiac death, while sodium glucose co-transporter-2 inhibitors (SGLT2-is) have been shown to possess cardioprotective effects in patients with hyperglycemia. The aim of this study was to investigate the impact of overweight on cardiac remodeling and the potential effect of SGLT2-is. Twenty-four rabbits were randomized into 4 groups: controls (Group 1), high-fat diet (HFD) (Group 2), controls treated with empagliflozin (Group 3), and HFD treated with empagliflozin (Group 4). All rabbits underwent electrophysiologic studies and ventricular tachycardia/ventricular fibrillation (VF) inducibility tests (maximal output with shortest 1:1 cycle length pacing). Atrial and ventricular myocardium were harvested for Western blot and Trichrome staining. Among all groups, Group 2 had the longest atrial effective refractory periods (ERPs) in both left and right atria, as well as the longest ventricular ERPs in both left and right ventricles. VF inducibility was highest in Group 2. The degree of fibrosis in both atria and ventricles was most severe in Group 2 and similar to that in Group 4. Enhanced calcium handling protein (CaV 1.2) expressions were noted in Group 2 compared to those in Group 1 and Group 3, respectively, and returned to baseline in Group 4. Overweight causes atrial and ventricular remodeling with prolongation of effective refractoriness, increased vulnerability to VF induction, upregulation of calcium handling proteins, and advanced fibrosis. Empagliflozin attenuates these remodeling effects, leading to decreased cardiac arrhythmogenicity and a reduced risk of sudden cardiac death.

Pnn deficiency alters expressions of calcium handling proteins and impairs nuclear envelope structure in cardiomyocytes

Abstract Pnn is a multi-functional protein playing roles in the regulation of gene transcription, mRNA alternative splicing, as well as cell-cell connection. Previous studies suggested an association between Pnn genetic defects and arrhythmogenic right ventricular cardiomyopathy (ARVC) in human. In this study, we applied an inducible cardiomyocyte-specific Pnn depletion mouse model (Myh6-CreERT2, Pnnflox/flox) to determine the impact of loss of Pnn on cardiac structure and function in mice. Six weeks after inducing Pnn gene disruption, electrocardiographic abnormalities, ventricular dilatation, and reduced left ventricular ejection fraction (LVEF) were observed in mice with loss of Pnn in cardiomyocytes. Histopathological examinations showed that the proliferation of cardiac fibroblasts and expression of α-smooth muscle actin were increased with Pnn depletion, while the cell-cell connection between cardiomyocytes were impaired. In addition to impaired intercalated discs, loss of Pnn also altered the distribution and expression of nuclear envelope proteins and the linker of nucleoskeleton and cytoskeleton (LINC) complex proteins, such as nuclear lamins, Emerin, and SUNs, in cardiomyocytes. Microarray analysis as well as subsequent RT-PCR and Western blots also indicated that loss of Pnn regulated myocardial expressions of genes responsible for calcium handling, such as RYR2, Atp2a2, Slc8a1, and Kcnj3. Furthermore, infiltrations of macrophages and neutrophiles were observed in the myocardium with Pnn depletion, while expression levels of oxidative stress-associated proteins were also significantly regulated by Pnn depletion. In conclusion, Pnn plays an essential role in the maintenance of intercalated disc integrity and nuclear envelope structure of cardiomyocytes, while cardiomyocyte-specific loss of Pnn impairs the calcium handling and leads to arrhythmogenic dilated cardiomyopathy in mice.Cardiac MRI of mice with Pnn depletionMyocardial expression of SUN2 and Emerin

Calcium handling abnormalities increase arrhythmia susceptibility in DMSXL myotonic dystrophy type 1 mice

BackgroundMyotonic dystrophy type 1 (DM1) is a multiorgan disorder with significant cardiac involvement. ECG abnormalities, including arrhythmias, occur in 80 % of DM1 patients and are the second-most common cause of death after respiratory complications; however, the mechanisms underlying the arrhythmogenesis remain unclear. The objective of this study was to investigate the basis of the electrophysiological abnormalities in DM1 using the DMSXL mouse model. MethodsECG parameters were evaluated at baseline and post flecainide challenge. Calcium transient and action potential parameters were evaluated in Langendorff-perfused hearts using fluorescence optical mapping. Calcium transient/sparks were evaluated in ventricular myocytes via confocal microscopy. Protein and mRNA levels for calcium handling proteins were evaluated using western blot and RT-qPCR, respectively. ResultsDMSXL mice showed arrhythmic events on ECG including premature ventricular contractions and sinus block. DMSXL mice showed increased calcium transient time to peak without any change to voltage parameters. Calcium alternans and both sustained and non-sustained ventricular tachyarrhythmias were readily inducible in DMSXL mice. The confocal experiments also showed calcium transient alternans and increased frequency of calcium sparks in DMSXL cardiomyocytes. These calcium abnormalities were correlated with increased RyR2 phosphorylation without changes to the other calcium handling proteins. ConclusionsThe DMSXL mouse model of DM1 exhibited enhanced arrhythmogenicity associated with abnormal intracellular calcium handling due to hyperphosphorylation of RyR2, pointing to RyR2 as a potential new therapeutic target in DM1 treatment.

Therapeutic Potential of Intermittent Hypoxia in Atrial Fibrillation

Intermittent hypoxia (IH) has been extensively studied in recent years, demonstrating adverse and beneficial effects on several physiological systems. However, the precise mechanism underlying its cardiac effects on the heart remains unclear. This study aims to explore the effect of treatment on atrial fibrillation under IH conditions, providing data that can potentially be used in the treatment of heart disease. An atrial fibrillation (AF) model was induced by injecting monocrotaline (MCT, 60 mg/kg) into rats. The study included 32 rats divided into four groups: Control, Control + IH, AF, and AF + IH. We evaluated molecular changes associated with AF using ELISA and Western blot and performed electrophysiological experiments to evaluate AF. Arrhythmia-related calcium and fibrosis markers were investigated. Phosphorylation levels of CaMKII, Phospholamban, and RyR2 all increased in the AF group but decreased in the IH-exposed group. Additionally, fibrosis marker expressions such as SMA, MMP2, MMP9, and TGF-β increased in the AF group but were significantly downregulated with IH treatment. Connexin 43 and AQP4 expression were restored in the IH-treated group. These findings suggest that IH may prevent AF by downregulating the expression of calcium-handling proteins and fibrosis-associated proteins in an AF-induced rat model.

Ubiquitin-specific protease 38 promotes atrial fibrillation in diabetic mice by stabilizing iron regulatory protein 2

BackgroundAtrial fibrillation (AF) is a common cardiovascular disease often observed in diabetes mellitus, and there is currently no satisfactory therapeutic option. Ubiquitin-specific protease 38 (USP38) has been implicated in the degradation of numerous substrate proteins in the myocardium. Herein, we aim to investigate the role of USP38 in AF induced by diabetes. MethodsCardiac-specific transgenic USP38 mice and cardiac-specific knockout USP38 mice were constructed, and streptozotocin was used to establish diabetic mouse model. Functional, electrophysiological, histologic, biochemical studies were performed. ResultsThe expression of USP38 was upregulated in atrial tissues of diabetic mice and HL-1 cells exposed to high glucose. USP38 overexpression increased susceptibility to AF, accompanied by aberrant expression of calcium-handling protein, heightened iron load and oxidation stress in diabetic mice. Conversely, USP38 deficiency reduced vulnerability to AF by hampering ferroptosis. Mechanistically, USP38 bound to iron regulatory protein 2 (IRP2), stabilizing it and remove K48-linked polyubiquitination chains, thereby increasing intracellular iron overload, lipid peroxidation, and ultimately contributing to ferroptosis. In addition, reduced iron overload by deferoxamine treatment alleviated oxidation stress and decreased vulnerability to AF in diabetic mice. ConclusionOverall, our findings reveal the detrimental role of USP38 in diabetes-related AF, manifested by increased level of iron overload and oxidation stress.

Abstract Mo120: Overexpression of Prostaglandin E2 EP3 Receptor Subtype Alters Calcium-Handling Proteins in Mouse Hearts

Prostaglandin E2 (PGE2) is an autacoid that acts through G-protein coupled receptors (EP1-EP4) in various cell types within the heart, including cardiomyocytes in which EP3 and EP4 predominate. We previously reported that mice with cardiomyocyte-specific overexpression of the EP3 receptor (EP3 TG) demonstrate reduced cardiac function and diminished cardiomyocyte contractility in isolated cardiomyocytes. We therefore hypothesized that PGE2 via the EP3 receptor regulates calcium handling proteins to reduce contractility. To test our hypothesis, we performed RNA sequencing (RNA seq) on the left ventricle of fifteen-week-old male EP3 TG mice along with their WT controls. Western blots were used to confirm changes in the expression of calcium-handling proteins such as Sarcoplasmic/endoplasmic reticulum calcium ATPase (SERCA2a), Ryanodine receptor 2 (RYR2), Phospholamban (PLB), Troponins (C, I, T) and voltage-gated calcium channel (CACNB2). For RNA seq, all data is reported as Log2Fold change, adjusted P value, and western blot data is reported as mean ± standard error (SE) of the mean. Additionally, isolated cardiomyocyte contractility was assessed using the IonOptix system, and data is reported as the mean ± SE. RNA seq data shows that SERCA2a and RYR2 expression were significantly downregulated in TG mice (SERCA2a -0.44, p=4.72 x 10 -6 ; RYR2: -0.86, p=4.08 x 10 -5 ) in addition to significant reductions in Troponin I (-0.43, p=0.038) and the Voltage-gated calcium channel (CACNB2: -0.71,p=0.0055). Western blot analyses confirmed the reductions in SERCA2a, RYR2, and CACNB2 although these changes were only significant for CACNB2 (1.0 ± 0.03 for WT vs 0.59 ± 0.04 for TG, p = 0.016). Expression of Troponins did not change in TG mice. Consistent with our previous data, IonOptix analysis shows reduced contractility of myocytes from EP3 TG mice (bl% peak h is 3.47 ± 0.20 for WT vs 1.0 ± 0.14 for TG, p<0.0001) despite a similar increase in the Ca 2+ transients (Ca 2+ peak h for WT= 0.86 ± 0.04 and TG=0.86 ± 0.07) suggesting potential changes in the sensitivity of the myofilament to Ca 2+ . In conclusion, the reduced contractility observed in EP3 TG mice may be due to alterations in calcium handling proteins and/or changes in calcium sensitivity at the level of the myofilament.

Abstract Mo127: Nitrate Supplementation Plus Voluntary Activity in C57Bl/6 Mice Improves Fitness and Impairs Cardiac Calcium Handling In a Sex Specific Fashion

Nitrate supplements are commonly combined with aerobic exercise to potentially improve performance and cardiac function. Whether this combination benefits cardiac function at the organ and cellular levels is unclear. We will determine if nitrates affect fitness or cardiac function in both sexes. C57Bl/6 mice (9-mos) were given 1mM sodium nitrate (drinking water) and/or access to a running wheel for 3 mos. Cardiac function (echocardiography), blood pressure (tail cuff) and fitness (treadmill) were measured. Calcium transients (Fura-2) and contractions (2Hz) were measured in ventricular myocytes and calcium handling proteins were measured by qPCR. In both sexes, nitrates did not change blood pressure or voluntary wheel running although females ran more than males (3.7±0.3km vs 2.2±0.3km, p=0.002). In exercised female mice, nitrates increased fitness from baseline while control did not (top speed at exhaustion: 24.2±1.4 to 28.0±1.5 cm/s, p=0.07 vs 23.3±1.0 to 30.7±2.0 cm/s, p=0.002) but nitrate supplemented males showed no fitness benefit. However, while exercise improved cardiac function and contractility compared to sedentary mice, nitrates plus exercise impaired cardiac function in a sex-specific manner. Nitrate-treated males who exercised had lower E/A ratios (1.8±0.3 vs 1.3±0.1, p=0.01) and worse diastolic function than control exercised males. By contrast, nitrate-treated female mice who exercised had smaller global longitudinal strain (-19.5±1.5 vs -11.8±3.0%, p=0.01) than controls, indicative of worse systolic function. Corresponding changes were seen at the cellular level. Exercised males given nitrates had slower a calcium transient decay than controls (44.8±4 vs 73.8±6 ms, p=0.01), while females given nitrates had slower velocity to peak calcium (0.031±0.004 vs 0.018±0.003 µm/ms, p=0.005) and smaller cellular contractions (2.9±0.5 µm vs 1.4±0.5 µm: p=0.03). Cardiac calcium handling proteins were also modified in females. Exercise plus nitrates caused a decrease in SERCA2a and ryanodine receptor 2 expression (mRNA) compared to the control exercise group. Studies in males are ongoing. Exercise plus nitrates increased fitness levels in only females and reduced cardiac function in a sex specific way when compared to exercise alone. This suggests a potential balance between benefits to fitness and potential cardiac complications that could affect athletes taking nitrate supplementation.

Abstract Tu079: The Calcium Handling Machinery and Electrophysiology is Remodeled in Friedreich’s Ataxia

Background: Friedreich's ataxia (FA) is a progressive neurodegenerative disorder. FA is caused by a deficiency in the frataxin protein due to an expansion of GAA repeats in the first intron of the frataxin gene. Reduced frataxin protein expression is thought to negatively affect mitochondrial function, leading to increased oxidative damage. Although FA is considered a neurodegenerative disorder, it is not completely understood why most patients present with left ventricular systolic dysfunction and die from cardiac events. Objective: The objective of our study is to determine whether abnormal calcium handling is a molecular mechanism of cardiac dysfunction in FA. Methods: We used the frataxin knock-out (KO) mouse model of FA as well as human heart samples from donors with FA and from unaffected donors. The expression of calcium-handling proteins was assessed using proteomics and westernblot. We used echocardiography and telemetric ECG to assess cardiac function in the mice. We also performed in-vivo programmed electrical stimulation (PES) to assess ventricular arrhythmogenesis in the mouse heart. Results: Proteomics and western blot showed that SERCA2, Ryr2, PLN, CASQ2, and CaMKII were downregulated and that the phosphorylation of Ryr2 and PLN (Ser16 and Thr17) were also significantly decreased in left ventricular tissue from humans with FA and from KO mice. The mitochondrial calcium handling proteins VDAC and MCU were upregulated in left ventricular tissue from humans with FA and from KO mice. On telemetric ECG, the RR tended to prolong in the KO animals compared to wild types (p=0.053), and heart rate variability analysis indicated heightened cardiac parasympathetic input. Echocardiography showed that the ejection fraction and fractional shortening were significantly decreased and left ventricular wall thickness and diameter were significantly increased in the KO mice. In PES, ventricular arrhythmogenesis was greater in KO mice compared to wild types. Conclusions: The reduced expression of calcium handling proteins may contribute to cardiac contractile and electrophysiological abnormalities in FA. Keywords: Friedreich's ataxia, SERCA2, Ryr2, PLN, CASQ2, and CaMKII.

Abstract We071: Identifying Preventive and Therapeutic Effects of SGLT2 Inhibitor on Atrial Fibrillation

Background: The frequency and prevalence of atrial fibrillation (AF) and heart failure are expected to increase over time, which are expected to result in enormous medical expenses and socioeconomic losses. Previous studies have confirmed that SGLT2 inhibitor (SGLT2i) reduces cardiovascular mortality and hospitalization rates in heart failure patients. Also, follow-up studies have been reported that the use of SGLT2i reduces atrial fibrillation, and its administration is recommended in clinical practice guidelines. In spite of beneficial effects of SGLT2i on atrial fibrillation, the exact mechanism by which SGLT2i reduces atrial fibrillation has not been revealed. Methods: We performed experiments by creating an AF cell model using Ang II and an AF animal model using Acetylcholin-Calcium chloride. Fibrosis markers and calcium regulatory proteins were confirmed by Western blot, and the occurrence and burden of AF were evaluated by using a 1F catheter in animal models. Results: In our cell studies and animal experiments, the inhibitory effect of SGLT2i administartion on atrial fibrillation was confirmed. First, fibrosis markers tend to reduce in atrial fibrillation models treated with SGLT2i, compared to non-treated atrial fibrillation models. In addition, the phosphorylation of the calcium handling proteins, such as CaMKII, RyR2, and PLB, increased in the AF group, whereas the degree of phosphorylation in SGLT2i treated group decreased to the phosphorylation level in control group. Conclusion: In AF-induced cell and animal models, the effect of SGLT2i was shown to be highly effective against atrial fibrillation. In particular, the results indicate that administration of SGLT2i before inducing atrial fibrillation could bring out the preventive and therapeutic effects through amelioration of fibrosis and reduction of calcium handling proteins phosphorylation.

Short-term aerobic exercise prevents development of glucocorticoid myopathic features in aged skeletal muscle in a sex-dependent manner.

Older adults are vulnerable to glucocorticoid-induced muscle atrophy and weakness, with sex potentially influencing their susceptibility to those effects. Aerobic exercise can reduce glucocorticoid-induced muscle atrophy in young rodents. However, it is unknown whether aerobic exercise can prevent glucocorticoid myopathy in aged muscle. The objectives of this study were to define the extent to which sex influences the development of glucocorticoid myopathy in aged muscle, and to determine the extent to which aerobic exercise training protects against myopathy development. Twenty-four-month-old female (n = 30) and male (n = 33) mice were randomized to either sedentary or aerobic exercise groups. Within their respective groups, mice were randomized to either daily treatment with dexamethasone (DEX) or saline. Upon completing treatments, the contractile properties of the triceps surae complex were assessed in situ. DEX marginally lowered muscle mass and soluble protein content in both sexes, which was attenuated by aerobic exercise only in females. DEX increased sub-tetanic force and rate of force development only in females, which was not influenced by aerobic exercise. Muscle fatigue was higher in both sexes following DEX, but aerobic exercise prevented fatigue induction only in females. The sex-specific differences to muscle function in response to DEX treatment coincided with sex-specific changes to the content of proteins related to calcium handling, mitochondrial quality control, reactive oxygen species production, and glucocorticoid receptor in muscle. These findings define several important sexually dimorphic changes to aged skeletal muscle physiology in response to glucocorticoid treatment and define the capacity of short-term aerobic exercise to protect against those changes. KEY POINTS: There are sexually dimorphic effects of glucocorticoids on aged skeletal muscle physiology. Glucocorticoid-induced changes to aged muscle contractile properties coincide with sex-specific differences in the content of calcium handling proteins. Aerobic exercise prevents glucocorticoid-induced fatigue only in aged females and coincides with differences in the content of mitochondrial quality control proteins and glucocorticoid receptors.

Right Ventricular Function and Oxidative Stress Improve with the Administration of Thyroid Hormones and Grape Juice in a Pulmonary Hypertension Model.

Adverse remodeling of lung vessels elevates pulmonary pressure and provokes pulmonary arterial hypertension (PAH). PAH results in increased right ventricle (RV) afterload, causing ventricular hypertrophy and the onset of heart failure. There is no specific treatment for maladaptive RV remodeling secondary to PAH. This study aims to explore two therapeutic approaches, grape juice (GJ) and thyroid hormones (TH), on PAH-induced oxidative stress and cardiac functional changes. Parameters of echocardiography related to lung vessel resistance (AT/ET ratio), RV contractility (TAPSE), and RV diastolic function (E/A peaks ratio) were evaluated. Also, total ROS, lipid peroxidation, antioxidant enzymes, calcium handling proteins, pro-oxidant and antioxidant protein expression were measured. Values of p<0.05 were considered statistically significant. Both GJ and TH treatments demonstrated reductions in pulmonary resistance (~22%) and improvements in TAPSE (inotropism ~11%) and AT/ET ratio (~26%) (p<0.05). There were no changes amongst groups regarding the E/A peak ratio. Although ROS and TBARS were not statistically significant, GJ and TH treatments decreased xanthine oxidase (~49%) levels and normalized HSP70 and calcium handling protein expression (p<0.05). However, only TH treatment ameliorated diastolic function (~50%) and augmented NRF2 immunocontent (~48%) (p<0.05). To the best of our knowledge, this study stands as a pioneer in showing that TH administered together with GJ promoted functional and biochemical improvements in a PAH model. Moreover, our data suggest that GJ and TH treatments were cardioprotective, combined or not, and exhibited their beneficial effects by modulating oxidative stress and calcium-handling proteins.

Cardiac stereotactic body radiotherapy to treat malignant ventricular arrhythmias directly affects the cardiomyocyte electrophysiology

BackgroundPromising as a treatment option for life-threatening ventricular arrhythmias, cardiac stereotactic body radiotherapy (cSBRT) has demonstrated early antiarrhythmic effects within days of treatment. The mechanisms underlying the immediate and short-term antiarrhythmic effects are poorly understood. ObjectiveWe hypothesize that cSBRT has a direct antiarrhythmic effect on cellular electrophysiology through reprogramming of ion channel and gap junction protein expression. MethodsAfter exposure to 20 Gy of x-rays in a single fraction, neonatal rat ventricular cardiomyocytes were analyzed 24 and 96 hours postradiation to determine changes in conduction velocity, beating frequency, calcium transients, and action potential duration in both monolayers and single cells. In addition, the expression of gap junction proteins, ion channels, and calcium handling proteins was evaluated at protein and messenger RNA levels. ResultsAfter irradiation with 20 Gy, neonatal rat ventricular cardiomyocytes exhibited increased beat rate and conduction velocity 24 and 96 hours after treatment. Messenger RNA and protein levels of ion channels were altered, with the most significant changes observed at the 96-hour mark. Upregulation of Cacna1c (Cav1.2), Kcnd3 (Kv4.3), Kcnh2 (Kv11.1), Kcnq1 (Kv7.1), Kcnk2 (K2P2.1), Kcnj2 (Kir2.1), and Gja1 (Cx43) was noted, along with improved gap junctional coupling. Calcium handling was affected, with increased Ryr2 ryanodin-rezeptor 2 and Slc8a1 Na+/Ca2+ exchanger expression and altered properties 96 hours posttreatment. Fibroblast and myofibroblast levels remained unchanged. ConclusioncSBRT modulates the expression of various ion channels, calcium handling proteins, and gap junction proteins. The described alterations in cellular electrophysiology may be the underlying cause of the immediate antiarrhythmic effects observed after cSBRT.

Cardiac dysfunction in sucrose-fed rats is associated with alterations of phospholamban phosphorylation and TNF-α levels

IntroductionHigh sucrose intake is linked to cardiovascular disease, a major global cause of mortality worldwide. Calcium mishandling and inflammation play crucial roles in cardiac disease pathophysiology. ObjectiveEvaluate if sucrose-induced obesity is related to deterioration of myocardial function due to alterations in the calcium-handling proteins in association with proinflammatory cytokines. MethodsWistar rats were divided into control and sucrose groups. Over eight weeks, Sucrose group received 30% sucrose water. Cardiac function was determined in vivo using echocardiography and in vitro using papillary muscle assay. Western blotting was used to detect calcium handling protein; ELISA assay was used to assess TNF-α and IL-6 levels. ResultsSucrose led to cardiac dysfunction. RYR2, SERCA2, NCX, pPBL Ser16 and L-type calcium channels were unchanged. However, pPBL-Thr17, and TNF-α levels were elevated in the S group. ConclusionSucrose induced cardiac dysfunction and decreased myocardial contractility in association with altered pPBL-Thr17 and elevated cardiac pro-inflammatory TNF-α.

Calcium signaling in endothelial and vascular smooth muscle cells: sex differences and the influence of estrogens and androgens.

Calcium signaling in vascular endothelial cells (ECs) and smooth muscle cells (VSMCs) is essential for the regulation of vascular tone. However, the changes to intracellular Ca2+ concentrations are often influenced by sex differences. Furthermore, a large body of evidence shows that sex hormone imbalance leads to dysregulation of Ca2+ signaling and this is a key factor in the pathogenesis of cardiovascular diseases. In this review, the effects of estrogens and androgens on vascular calcium-handling proteins are discussed, with emphasis on the associated genomic or nongenomic molecular mechanisms. The experimental models from which data were collected were also considered. The review highlights 1) in female ECs, transient receptor potential vanilloid 4 (TRPV4) and mitochondrial Ca2+ uniporter (MCU) enhance Ca2+-dependent nitric oxide (NO) generation. In males, only transient receptor potential canonical 3 (TRPC3) plays a fundamental role in this effect. 2) Female VSMCs have lower cytosolic Ca2+ levels than males due to differences in the activity and expression of stromal interaction molecule 1 (STIM1), calcium release-activated calcium modulator 1 (Orai1), calcium voltage-gated channel subunit-α1C (CaV1.2), Na+-K+-2Cl- symporter (NKCC1), and the Na+/K+-ATPase. 3) When compared with androgens, the influence of estrogens on Ca2+ homeostasis, vascular tone, and incidence of vascular disease is better documented. 4) Many studies use supraphysiological concentrations of sex hormones, which may limit the physiological relevance of outcomes. 5) Sex-dependent differences in Ca2+ signaling mean both sexes ought to be included in experimental design.

Função do Ventrículo Direito e Estresse Oxidativo Melhoram com a Administração de Hormônios da Tireoide e Suco de Uva em um Modelo de Hipertensão Pulmonar

Abstract Background Adverse remodeling of lung vessels elevates pulmonary pressure and provokes pulmonary arterial hypertension (PAH). PAH results in increased right ventricle (RV) afterload, causing ventricular hypertrophy and the onset of heart failure. There is no specific treatment for maladaptive RV remodeling secondary to PAH. Objectives This study aims to explore two therapeutic approaches, grape juice (GJ) and thyroid hormones (TH), on PAH-induced oxidative stress and cardiac functional changes. Methods Parameters of echocardiography related to lung vessel resistance (AT/ET ratio), RV contractility (TAPSE), and RV diastolic function (E/A peaks ratio) were evaluated. Also, total ROS, lipid peroxidation, antioxidant enzymes, calcium handling proteins, pro-oxidant and antioxidant protein expression were measured. Values of p&lt;0.05 were considered statistically significant. Results Both GJ and TH treatments demonstrated reductions in pulmonary resistance (~22%) and improvements in TAPSE (inotropism ~11%) and AT/ET ratio (~26%) (p&lt;0.05). There were no changes amongst groups regarding the E/A peak ratio. Although ROS and TBARS were not statistically significant, GJ and TH treatments decreased xanthine oxidase (~49%) levels and normalized HSP70 and calcium handling protein expression (p&lt;0.05). However, only TH treatment ameliorated diastolic function (~50%) and augmented NRF2 immunocontent (~48%) (p&lt;0.05). Conclusions To the best of our knowledge, this study stands as a pioneer in showing that TH administered together with GJ promoted functional and biochemical improvements in a PAH model. Moreover, our data suggest that GJ and TH treatments were cardioprotective, combined or not, and exhibited their beneficial effects by modulating oxidative stress and calcium-handling proteins.

Ubiquitin-specific protease 38 promotes inflammatory atrial fibrillation induced by pressure overload.

Atrial structural and electrical remodelling is a major reason for the initiation and perpetuation of atrial fibrillation (AF). Ubiquitin-specific protease 38 (USP38) is a deubiquitinating enzyme, but its function in the heart remains unknown. The aim of this study was to investigate the effect of USP38 in pressure overload-induced AF. Cardiac-specific knockout USP38 and cardiac-specific transgenic USP38 mice and their corresponding control mice were used in this study. After 4 weeks with or without aortic banding (AB) surgery, atrial echocardiography, atrial histology, electrophysiological study, and molecular analysis were assessed. Ubiquitin-specific protease 38 knockout mice showed a remarkable improvement in vulnerability to AF, atrial weight and diameter, atrial fibrosis, and calcium-handling protein expression after AB surgery. Conversely, USP38 overexpression further increased susceptibility to AF by exacerbating atrial structural and electrical remodelling. Mechanistically, USP38 interacted with and deubiquitinated nuclear factor-kappa B (NF-κB), and USP38 overexpression increased the level of p-NF-κB in vivo and in vitro, accompanied by the upregulation of NOD-like receptor protein 3 (NLRP3) and inflammatory cytokines, suggesting that USP38 contributes to adverse effects by driving NF-κB/NLRP3-mediated inflammatory responses. Overall, our study indicates that USP38 promotes pressure overload-induced AF through targeting NF-κB/NLRP3-mediated inflammatory responses.

Modification-Specific Proteomic Analysis Reveals Cysteine S-Nitrosylation Mediated the Effect of Preslaughter Transport Stress on Pork Quality Development.

This study aimed to explore the effects of preslaughter transport stress on protein S-nitrosylation levels and S-nitrosylated proteome in post-mortem pork longissimus thoracis (LT) muscle. Pigs (N= 16) were randomly divided into 3 h transport (high-stress group, HS) and 3 h transport followed by 3 h resting treatments (low-stress control group, LS). Results demonstrated that high transport stress levels induced nitric oxide (NO) overproduction by promoting NO synthase (NOS) activity and neuronal NOS (nNOS) expression, which thereby notably increased protein S-nitrosylation levels in post-mortem muscle (p < 0.05). Proteomic analysis indicated that 133 S-nitrosylation-modified cysteines belonging to 85 proteins were significantly differential, of which 101 cysteines of 63 proteins were higher in the HS group (p < 0.05). Differential proteins including cytoskeletal and calcium-handling proteins, glycolytic enzymes, and oxidoreductase were mainly involved in the regulation of muscle contraction and energy metabolism that might together mediate meat quality development. Overall, this study provided direct evidence for changes in S-nitrosylation levels and proteome in post-mortem muscle in response to preslaughter transport stress and revealed the potential impact of S-nitrosylated proteins on meat quality.

Clinical and genetic characteristics of catecholaminergic polymorphic ventricular tachycardia combined with left ventricular non-compaction.

Catecholaminergic polymorphic ventricular tachycardia is an ion channelopathy, caused by mutations in genes coding for calcium-handling proteins. It can coexist with left ventricular non-compaction. We aim to investigate the clinical and genetic characteristics of this co-phenotype. Medical records of 24 patients diagnosed with catecholaminergic polymorphic ventricular tachycardia in two Chinese hospitals between September, 2005, and January, 2020, were retrospectively reviewed. We evaluated their clinical and genetic characteristics, including basic demographic data, electrocardiogram parameters, medications and survival during follow-up, and their gene mutations. We did structural analysis for a novel variant ryanodine receptor 2-E4005V. The patients included 19 with catecholaminergic polymorphic ventricular tachycardia mono-phenotype and 5 catecholaminergic polymorphic ventricular tachycardia-left ventricular non-compaction overlap patients. The median age of onset symptoms was 9.0 (8.0,13.5) years. Most patients (91.7%) had cardiac symptoms, and 50% had a family history of syncope. Overlap patients had lower peak heart rate and threshold heart rate for ventricular tachycardia and ventricular premature beat during the exercise stress test (p < 0.05). Sudden cardiac death risk may be higher in overlap patients during follow-up. Gene sequencing revealed 1 novel ryanodine receptor 2 missense mutation E4005V and 1 mutation previously unreported in catecholaminergic polymorphic ventricular tachycardia, but no left ventricular non-compaction-causing mutations were observed. In-silico analysis showed the novel mutation E4005V broke down the interaction between two charged residues. Catecholaminergic polymorphic ventricular tachycardia overlapping with left ventricular non-compaction may lead to ventricular premature beat/ventricular tachycardia during exercise stress test at lower threshold heart rate than catecholaminergic polymorphic ventricular tachycardia alone; it may also indicate a worse prognosis and requires strict follow-up. ryanodine receptor 2 mutations disrupted interactions between residues and may interfere the function of ryanodine receptor 2.

Cardiovascular phenotype of the duchenne muscular dystrophy carrier female rat

Abstract Background Duchenne muscular dystrophy (DMD) is a lethal, severely progressive muscle-wasting disease. It is an X-linked recessive disease caused by mutations in the DMD gene encoding dystrophin protein and consequently the absence of dystrophin protein synthesis. Besides the skeletal muscle abnormalities, DMD patients are often suffering cardiovascular symptoms include cardiac fibrosis, dilated cardiomyopathy, arrhythmia, and congestive heart failure. Heterozygous female DMD carriers rarely acquire skeletal muscle symptoms, however the cardiac abnormalities are often underrepresented. There are few studies to date characterizing cardiovascular abnormalities in female DMD carriers and the mechanisms underlying the cardiac manifestations are still not fully known. Aims and Methods: Therefore, the aim of this study was to investigate the cardiovascular phenotype of 9 months old female DMD carrier rats and compare with age-matched wildtype rats. Objectives included assessment of cardiac function via transthoracic echocardiography, vascular function using wire myography, cardiac fibrosis and dystrophin via histology, mRNA expression of inflammatory markers via RT-qPCR, measurements of ACE1 and ACE2 activity, as well as expression of dystrophin, SERCA, sarcolipin, BAG3, and Connexin43 (Cx43) using western blotting. The cardiac function, vascular endothelial function, ACE1 and ACE2 activity, and collagen deposition in cardiac tissue were similar between the female DMD carrier and wildtype rats. The echocardiography data revealed thinning of the left-ventricular posterior wall indicating trend towards cardiac atrophy and dysfunction (p&amp;lt;0.05). Wire myography data showed trends of impaired endothelium-independent relaxation and hypercontractility, suggesting the potential vascular abnormalities. Histological analysis showed thickening of intima-media layer in coronary arteries, addition to reduced dystrophin staining, further affirming dystrophin loss impairs smooth muscle cell function (p&amp;lt;0.05, respectively). Protein expression of dystrophin, SERCA2, and BAG3 was decreased in female DMD carrier rats in the myocardium. We also found decreased levels of Cx43 at the intercalated discs, with a concomitant increase in the phosphorylation of Serine368 on Cx43 that very often precedes ubiquitination and degradation of Cx43 channels. In agreement, higher levels of the ubiquitin ligase Nedd4 were observed in hearts of female DMD carrier rats, implicating Cx43 degradation in cardiac dysfunction observed in these animals. Conclusions These findings indicate that female DMD carrier rats do not develop severe cardiac systolic dysfunction nor dilated cardiomyopathy at the age of 9 months unlike male DMD rats as previously described(1). However, the female DMD carrier rats begin to manifest tendencies towards cardiac and vascular dysfunction in association with a changes of calcium handling protein and Cx 43 expression in the heart.

Neural mechanism facilitating PM2.5-related cardiac arrhythmias through cardiovascular autonomic and calcium dysregulation in a rat model

Particulate matter < 2.5 μm (PM2.5) exposure is associated with increased arrhythmia events and cardiovascular mortality, but the detailed mechanism remained elusive. In the current study, we aimed to investigate the autonomic alterations in a rodent model after acute exposure to PM2.5. Twelve male WKY rats were randomized to control and PM2.5 groups. All were treated with 2 exposures of oropharyngeal aerosol inhalations (1 μg PM2.5 per gram of body weight in 100 μL normal saline for the PM2.5 group) separately by 7 days. Polysomnography and electrocardiography were surgically installed 7 days before oropharyngeal inhalation and monitored for 7 days after each inhalation. Physiologic monitors were used to define active waking (AW), quiet sleep (QS), and paradoxical sleep (PS). Autonomic regulations were measured by heart rate variability (HRV). The protein expression of ventricular tissue of the 2 groups was compared at the end of the experiment. In sleep pattern analysis, QS interruption of the PM2.5 group was significantly higher than the control group (0.52 ± 0.13 events/min, 0.35 ± 0.10 events/min, p = 0.002). In HRV analysis, the LF/HF was significantly higher for the PM2.5 group than the control group (1.15 ± 0.16, 0.64± 0.30, p = 0.003), largely driven by LF/HF increase during the QS phase. Ionic channel protein expression from Western blots showed that the PM2.5 group had significantly lower L-type calcium channel and higher SERCA2 and rectifier potassium channel expressions than the control group, respectively. Our results showed that acute PM2.5 exposure leads to interruption of QS, sympathetic activation, and recruitment of compensatory calcium handling proteins. The autonomic and calcium dysregulations developed after PM 2.5 exposure may explain the risk of sleep disturbance and sleep-related arrhythmia.