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Billur D, Olgar Y, Turan B. Intracellular Redistribution of Left Ventricular Connexin 43 Contributes to the Remodeling of Electrical Properties of the Heart in Insulin-resistant Elderly Rats. J Histochem Cytochem 2022; 70:447-462. [PMID: 35608408 DOI: 10.1369/00221554221101661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The correlation between long-QT and connexin 43 (Cx43) status and localization in elderly rats was determined to demonstrate a correlation between insulin resistance (I-R), ischemia-reperfusion, aging, and heart dysfunction. Male Wistar rats are grouped as 24-month-old rats (Aged-group), those with metabolic syndrome (8 months old; MetS-group), or controls (8 months old; Con-group). Both experimental groups have long-QT and low heart rate. Immunohistochemical imaging and quantification showed marked decreases in Cx43 staining of intercalated disc with less localizations in the Aged-group and MetS-group. The lateralization of Cx43 on longitudinal cell membrane was significantly high in the MetS-group than in the Con-group with no significant change in the Aged-group. Its significant cytoplasmic internalization was higher in the Aged-group than in the MetS-group. There were marked decreases in phospho-Cx43 (pCx43) staining of intercalated disc with less localizations in both groups than in the Con-group. Furthermore, lateralization of pCx43 was significantly low in the Aged-group and MetS-group, whereas there were no significant changes in the cytoplasmic internalization of both groups compared with the Con-group. Furthermore, the ratio of pCx43 to Cx43 was significantly small in both groups. We determined increases in RhoA and endothelin-1 in both groups, further supporting decreases in pCx43. Our data indicate the important role of I-R on long-QT in aging heart through alterations in both Cx43 protein level and localizations, leading to an abnormal spreading of ventricular repolarization in I-R heart.
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Affiliation(s)
| | | | - Belma Turan
- Department of Biophysics.,Faculty of Medicine, Ankara University, Ankara, Turkey, and Department of Biophysics, Faculty of Medicine, Lokman Hekim University, Ankara, Turkey
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Olgar Y, Tuncay E, Billur D, Turan B. Bimodal Effects of P2Y 12 Antagonism on Matrix Metalloproteinase-Associated Contractile Dysfunction in İnsulin-Resistant Mammalian Heart. Biol Trace Elem Res 2022; 200:2195-2204. [PMID: 34268701 DOI: 10.1007/s12011-021-02816-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Accepted: 06/29/2021] [Indexed: 10/20/2022]
Abstract
The matrix metalloproteinases (MMPs) contribute to matrix remodeling in diabetes via tissue degradation; however, their contributions can be different depending on the pathology. For instance, MMPs are elevated in acute stress hyperglycemia, whereas they can be degraded in chronic hyperglycemia. Since studies emphasize the possible cardioprotective effect of ticagrelor (Tica) beyond its antiplatelet action, we aimed to examine whether Tica treatment can reverse the depressed heart function of metabolic syndrome (MetS) rats via affecting the expression levels of MMPs. Tica treatment of high-carbohydrate-induced MetS rats could not affect significantly the depressed contractile activity of Langendorff-perfused heart preparations. On the other hand, the Tica treatment provided a significant recovery in the reduced relaxation activity of the aortic preparations from the same animals. Histological examination of the hearts demonstrated marked damages in Mets rats, such as increases in the number of foamy cells and accumulation of collagen fiber and increases in the elastic lamellar irregularity of tunica media, while Tica treatment provided a slight improvement in the structure of left ventricle tissue. We also could not obtain a significant reverse in the high cytosolic labile Zn2+ ([Zn2+]i) with the treatment of cardiomyocytes with Tica. Furthermore, Tica treatment of MetS rats could not significantly reverse the degraded protein levels of MMP-2 and MMP-9 in the heart, as well. Overall, we demonstrated that Tica treatment of MetS rats has no significant benefits on the depressed heart function, although provide a significant beneficial impact on vascular relaxation. This action of Tica may be through its lack of action on both MMP degradation and high [Zn2+]i, which can further precipitate in cleavage of extracellular matrix in the heart.
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Affiliation(s)
- Yusuf Olgar
- Department of Biophysics, Faculty of Medicine, Ankara University, Ankara, Turkey
| | - Erkan Tuncay
- Department of Biophysics, Faculty of Medicine, Ankara University, Ankara, Turkey
| | - Deniz Billur
- Department of Histology and Embryology, Faculty of Medicine, Ankara University, Ankara, Turkey
| | - Belma Turan
- Department of Biophysics, Faculty of Medicine, Ankara University, Ankara, Turkey.
- Department of Biophysics, Faculty of Medicine, Lokman Hekim University, Ankara, Turkey.
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Olgar Y, Durak A, Bitirim CV, Tuncay E, Turan B. Insulin acts as an atypical KCNQ1/KCNE1-current activator and reverses long QT in insulin-resistant aged rats by accelerating the ventricular action potential repolarization through affecting the β 3 -adrenergic receptor signaling pathway. J Cell Physiol 2021; 237:1353-1371. [PMID: 34632595 DOI: 10.1002/jcp.30597] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Revised: 09/22/2021] [Accepted: 09/24/2021] [Indexed: 12/13/2022]
Abstract
Insufficient-heart function is associated with myocardial insulin resistance in the elderly, particularly associated with long-QT, in a dependency on dysfunctional KCNQ1/KCNE1-channels. So, we aimed to examine the contribution of alterations in KCNQ1/KCNE1-current (IKs ) to the aging-related remodeling of the heart as well as the role of insulin treatment on IKs in the aged rats. Prolonged late-phase action potential (AP) repolarization of ventricular cardiomyocytes from insulin-resistant 24-month-old rats was significantly reversed by in vitro treatment of insulin or PKG inhibitor (in vivo, as well) via recovery in depressed IKs . Although the protein level of either KCNQ1 or KCNE1 in cardiomyocytes was not affected with aging, PKG level was significantly increased in those cells. The inhibited IKs in β3 -ARs-stimulated cells could be reversed with a PKG inhibitor, indicating the correlation between PKG-activation and β3 -ARs activation. Furthermore, in vivo treatment of aged rats, characterized by β3 -ARs activation, with either insulin or a PKG inhibitor for 2 weeks provided significant recoveries in IKs , prolonged late phases of APs, prolonged QT-intervals, and low heart rates without no effect on insulin resistance. In vivo insulin treatment provided also significant recovery in increased PKG and decreased PIP2 level, without the insulin effect on the KCNQ1 level in β3 -ARs overexpressed cells. The inhibition of IKs in aged-rat cardiomyocytes seems to be associated with activated β3 -ARs dependent remodeling in the interaction between KCNQ1 and KCNE1. Significant recoveries in ventricular-repolarization of insulin-treated aged cardiomyocytes via recovery in IKs strongly emphasize two important issues: (1) IKs can be a novel target in aging-associated remodeling in the heart and insulin may be a cardioprotective agent in the maintenance of normal heart function during the aging process. (2) This study is one of the first to demonstrate insulin's benefits on long-QT in insulin-resistant aged rats by accelerating the ventricular AP repolarization through reversing the depressed IKs via affecting the β3 -ARs signaling pathway and particularly affecting activated PKG.
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Affiliation(s)
- Yusuf Olgar
- Department of Biophysics, Faculty of Medicine, Ankara University, Ankara, Turkey
| | - Aysegul Durak
- Department of Biophysics, Faculty of Medicine, Ankara University, Ankara, Turkey
| | | | - Erkan Tuncay
- Department of Biophysics, Faculty of Medicine, Ankara University, Ankara, Turkey
| | - Belma Turan
- Department of Biophysics, Faculty of Medicine, Ankara University, Ankara, Turkey.,Department of Biophysics, Faculty of Medicine, Lokman Hekim University, Ankara, Turkey
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4
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Durak A, Akkus E, Canpolat AG, Tuncay E, Corapcioglu D, Turan B. Glucagon-like peptide-1 receptor agonist treatment of high carbohydrate intake-induced metabolic syndrome provides pleiotropic effects on cardiac dysfunction through alleviations in electrical and intracellular Ca 2+ abnormalities and mitochondrial dysfunction. Clin Exp Pharmacol Physiol 2021; 49:46-59. [PMID: 34519087 DOI: 10.1111/1440-1681.13590] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 09/07/2021] [Accepted: 09/10/2021] [Indexed: 02/06/2023]
Abstract
The pleiotropic effects of glucagon-like peptide-1 receptor (GLP-1R) agonists on the heart have been recognised in obese or diabetic patients. However, little is known regarding the molecular mechanisms of these agonists in cardioprotective actions under metabolic disturbances. We evaluated the effects of GLP-1R agonist liraglutide treatment on left ventricular cardiomyocytes from high-carbohydrate induced metabolic syndrome rats (MetS rats), characterised with insulin resistance and cardiac dysfunction with a long-QT. Liraglutide (0.3 mg/kg for 4 weeks) treatment of MetS rats significantly reversed long-QT, through a shortening the prolonged action potential duration and recovering inhibited K+ -currents. We also determined a significant recovery in the leaky sarcoplasmic reticulum (SR) and high cytosolic Ca2+ -level, which are confirmed with a full recovery in activated Na+ /Ca2+ -exchanger currents (INCX ). Moreover, the liraglutide treatment significantly reversed the depolarised mitochondrial membrane potential (MMP), increased production of oxidant markers, and cellular acidification together with the depressed ATP production. Our light microscopy analysis of isolated cardiomyocytes showed marked recoveries in the liraglutide-treated MetS group such as marked reverses in highly dilated T-tubules and SR-mitochondria junctions. Moreover, we determined a significant increase in depressed GLUT4 protein level in liraglutide-treated MetS group, possibly associated with recovery in casein kinase 2α. Overall, the study demonstrated a molecular mechanism of liraglutide-induced cardioprotection in MetS rats, at most, via its pleiotropic effects, such as alleviation in the electrical abnormalities, Ca2+ -homeostasis, and mitochondrial dysfunction in ventricular cardiomyocytes.
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Affiliation(s)
- Aysegul Durak
- Faculty of Medicine, Department of Biophysics, Ankara University, Ankara, Turkey
| | - Erman Akkus
- Faculty of Medicine, Department of Internal Medicine, Ankara University, Ankara, Turkey
| | - Asena Gokcay Canpolat
- Faculty of Medicine, Department of Endocrinology and Metabolism, Ankara University, Ankara, Turkey
| | - Erkan Tuncay
- Faculty of Medicine, Department of Biophysics, Ankara University, Ankara, Turkey
| | - Demet Corapcioglu
- Faculty of Medicine, Department of Endocrinology and Metabolism, Ankara University, Ankara, Turkey
| | - Belma Turan
- Faculty of Medicine, Department of Biophysics, Ankara University, Ankara, Turkey.,Faculty of Medicine, Department of Biophysics, Lokman Hekim University, Ankara, Turkey
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Alyu F, Olgar Y, Degirmenci S, Turan B, Ozturk Y. Interrelated In Vitro Mechanisms of Sibutramine-Induced Cardiotoxicity. Cardiovasc Toxicol 2021; 21:322-335. [PMID: 33389602 DOI: 10.1007/s12012-020-09622-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Accepted: 11/24/2020] [Indexed: 11/26/2022]
Abstract
Consumption of illicit pharmaceutical products containing sibutramine has been reported to cause cardiovascular toxicity problems. This study aimed to demonstrate the toxicity profile of sibutramine, and thereby provide important implications for the development of more effective strategies in both clinical approaches and drug design studies. Action potentials (APs) were determined from freshly isolated ventricular cardiomyocytes with whole-cell configuration of current clamp as online. The maximum amplitude of APs (MAPs), the resting membrane potential (RMP), and AP duration from the repolarization phases were calculated from original records. The voltage-dependent K+-channel currents (IK) were recorded in the presence of external Cd2+ and both inward and outward parts of the current were calculated, while their expression levels were determined with qPCR. The levels of intracellular free Ca2+ and H+ (pHi) as well as reactive oxygen species (ROS) were measured using either a ratiometric micro-spectrofluorometer or confocal microscope. The mechanical activity of isolated hearts was observed with Langendorff-perfusion system. Acute sibutramine applications (10-8-10-5 M) induced significant alterations in both MAPs and RMP as well as the repolarization phases of APs and IK in a concentration-dependent manner. Sibutramine (10 μM) induced Ca2+-release from the sarcoplasmic reticulum under either electrical or caffeine stimulation, whereas it depressed left ventricular developed pressure with a marked decrease in the end-diastolic pressure. pHi inhibition by sibutramine supports the observed negative alterations in contractility. Changes in mRNA levels of different IK subunits are consistent with the acute inhibition of the repolarizing IK, affecting AP parameters, and provoke the cardiotoxicity.
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Affiliation(s)
- Feyza Alyu
- Department of Pharmacology, Faculty of Pharmacy, Anadolu University, Yunus Emre Campus, 26470, Eskisehir, Turkey
| | - Yusuf Olgar
- Department of Biophysics, Faculty of Medicine, Ankara University, 06230, Ankara, Turkey
| | - Sinan Degirmenci
- Department of Biophysics, Faculty of Medicine, Ankara University, 06230, Ankara, Turkey
| | - Belma Turan
- Department of Biophysics, Faculty of Medicine, Ankara University, 06230, Ankara, Turkey
- Department of Biophysics, Faculty of Medicine, Lokman Hekim University, 06230, Ankara, Turkey
| | - Yusuf Ozturk
- Department of Pharmacology, Faculty of Pharmacy, Anadolu University, Yunus Emre Campus, 26470, Eskisehir, Turkey.
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Durak A, Bitirim CV, Turan B. Titin and CK2α are New Intracellular Targets in Acute Insulin Application-Associated Benefits on Electrophysiological Parameters of Left Ventricular Cardiomyocytes From Insulin-Resistant Metabolic Syndrome Rats. Cardiovasc Drugs Ther 2020; 34:487-501. [PMID: 32377826 DOI: 10.1007/s10557-020-06974-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
BACKGROUND Previous studies have demonstrated that a high-carbohydrate intake could induce metabolic syndrome (MetS) in male rats with marked cardiac functional abnormalities. In addition, studies mentioned some benefits of insulin application on these complications, but there are considerable disagreements among their findings. Therefore, we aimed to extend our knowledge on the in-vitro influence of insulin on left ventricular dysfunction and also in the isolated cardiomyocytes from MetS rats. RESULTS At the organ function level, an acute insulin application (100-nM) provided an important beneficial effect on the left ventricular developed pressure in MetS rats. Furthermore, to treat the freshly isolated cardiomyocytes from MetS rats with insulin provided marked recoveries in elevated resting intracellular Ca2+-level, as well as significant prevention of prolonged action potential through an augmentation in depressed K+-channel currents. Insulin also normalized the cellular levels of increased ROS and phosphorylation of PKCα, together with normalizations of apoptotic markers in MetS cardiomyocytes through the insulin-mediated regulation of phospho-Akt. Since not only elevated PKCα-activity but also reductions in phospho-Akt are key modulators of titin-based cardiomyocyte stiffening in hyperglycemia, insulin treatment of the cardiomyocytes prevented the activation of titin via the above pathways. Furthermore, CK2α-activation and NOS-phosphorylation could be prevented with insulin treatment. Mechanistically, we found that impaired insulin signaling and elevated PKCα and CK2α activities, as well as depressed Akt phosphorylation, are key modulators of titin-based cardiomyocyte stiffening in MetS rats. CONCLUSION We propose that restoring normal kinase activities and also increases in phospho-Akt by insulin can contribute marked recoveries in MetS heart function, indicating a promising approach to modulate titin-associated factors in heart dysfunction associated with type-2 diabetes mellitus. Graphical Abstract.
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Affiliation(s)
- Aysegul Durak
- Department of Biophysics, Faculty of Medicine, Ankara University, Ankara, Turkey
| | | | - Belma Turan
- Department of Biophysics, Faculty of Medicine, Ankara University, Ankara, Turkey.
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7
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Erdogan BR, Michel MC, Arioglu-Inan E. Expression and Signaling of β-Adrenoceptor Subtypes in the Diabetic Heart. Cells 2020; 9:cells9122548. [PMID: 33256212 PMCID: PMC7759850 DOI: 10.3390/cells9122548] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 11/20/2020] [Accepted: 11/24/2020] [Indexed: 12/18/2022] Open
Abstract
Diabetes is a chronic, endocrine disorder that effects millions of people worldwide. Cardiovascular complications are the major cause of diabetes-related morbidity and mortality. Cardiac β1- and β2-adrenoceptor (AR) stimulation mediates positive inotropy and chronotropy, whereas β3-AR mediates negative inotropic effect. Changes in β-AR responsiveness are thought to be an important factor that contributes to the diabetic cardiac dysfunction. Diabetes related changes in β-AR expression, signaling, and β-AR mediated cardiac function have been studied by several investigators for many years. In the present review, we have screened PubMed database to obtain relevant articles on this topic. Our search has ended up with wide range of different findings about the effect of diabetes on β-AR mediated changes both in molecular and functional level. Considering these inconsistent findings, the effect of diabetes on cardiac β-AR still remains to be clarified.
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Affiliation(s)
- Betul R. Erdogan
- Department of Pharmacology, Faculty of Pharmacy, Ankara University, 06560 Ankara, Turkey;
- Department of Pharmacology, Faculty of Pharmacy, Izmir Katip Celebi University, 35620 Izmir, Turkey
| | - Martin C. Michel
- Department of Pharmacology, Johannes Gutenberg University, 55131 Mainz, Germany;
| | - Ebru Arioglu-Inan
- Department of Pharmacology, Faculty of Pharmacy, Ankara University, 06560 Ankara, Turkey;
- Correspondence:
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Mitochondria-Targeting Antioxidant Provides Cardioprotection through Regulation of Cytosolic and Mitochondrial Zn 2+ Levels with Re-Distribution of Zn 2+-Transporters in Aged Rat Cardiomyocytes. Int J Mol Sci 2019; 20:ijms20153783. [PMID: 31382470 PMCID: PMC6695787 DOI: 10.3390/ijms20153783] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Revised: 06/12/2019] [Accepted: 06/17/2019] [Indexed: 12/29/2022] Open
Abstract
Aging is an important risk factor for cardiac dysfunction. Heart during aging exhibits a depressed mechanical activity, at least, through mitochondria-originated increases in ROS. Previously, we also have shown a close relationship between increased ROS and cellular intracellular free Zn2+ ([Zn2+]i) in cardiomyocytes under pathological conditions as well as the contribution of some re-expressed levels of Zn2+-transporters for redistribution of [Zn2+]i among suborganelles. Therefore, we first examined the cellular (total) [Zn2+] and then determined the protein expression levels of Zn2+-transporters in freshly isolated ventricular cardiomyocytes from 24-month rat heart compared to those of 6-month rats. The [Zn2+]i in the aged-cardiomyocytes was increased, at most, due to increased ZIP7 and ZnT8 with decreased levels of ZIP8 and ZnT7. To examine redistribution of the cellular [Zn2+]i among suborganelles, such as Sarco/endoplasmic reticulum, S(E)R, and mitochondria ([Zn2+]SER and [Zn2+]Mit), a cell model (with galactose) to mimic the aged-cell in rat ventricular cell line H9c2 was used and demonstrated that there were significant increases in [Zn2+]Mit with decreases in [Zn2+]SER. In addition, the re-distribution of these Zn2+-transporters were markedly changed in mitochondria (increases in ZnT7 and ZnT8 with no changes in ZIP7 and ZIP8) and S(E)R (increase in ZIP7 and decrease in ZnT7 with no changes in both ZIP8 and ZnT8) both of them isolated from freshly isolated ventricular cardiomyocytes from aged-rats. Furthermore, we demonstrated that cellular levels of ROS, both total and mitochondrial lysine acetylation (K-Acetylation), and protein-thiol oxidation were significantly high in aged-cardiomyocytes from 24-month old rats. Using a mitochondrial-targeting antioxidant, MitoTEMPO (1 µM, 5-h incubation), we provided an important data associated with the role of mitochondrial-ROS production in the [Zn2+]i-dyshomeostasis of the ventricular cardiomyocytes from 24-month old rats. Overall, our present data, for the first time, demonstrated that a direct mitochondria-targeting antioxidant treatment can be a new therapeutic strategy during aging in the heart through a well-controlled [Zn2+] distribution among cytosol and suborganelles with altered expression levels of the Zn2+-transporters.
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Okatan EN, Turan B. The contribution of phosphodiesterases to cardiac dysfunction in rats with metabolic syndrome induced by a high-carbohydrate diet. Can J Physiol Pharmacol 2019; 97:1064-1072. [PMID: 31299169 DOI: 10.1139/cjpp-2019-0006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Metabolic syndrome (MetS) is a cluster of risk factors, including insulin resistance among others, underlying the development of diabetes and (or) cardiovascular diseases. Studies show a close relationship between cardiac dysfunction and abnormal cAMP catabolism, which contributes to pathological remodelling. Stimulating the synthesis of cAMP via suppression of phosphodiesterases (PDEs) has positive therapeutic effects. Therefore, we examined the role of PDEs on cardiac dysfunction in high-carbohydrate diet-induced MetS rats. We first demonstrated significantly high expression levels of PDE3 and PDE4, the most highly expressed subtypes, together with depressed cAMP levels in heart tissue from MetS rats. Second, we demonstrated the activity of these PDEs by using either their basal or PDE inhibitor-induced intracellular levels of cAMP and Ca2+, the transient intracellular Ca2+ changes under electrical stimulation, isometric contractions in papillary muscle strips and some key signalling proteins (such as RyR2, PLN, PP1A, and PKA) are responsible for the Ca2+ homeostasis in isolated cardiomyocytes from MetS rats. The clear recovery in decreased basal cAMP levels, increased protein expression levels of PDE3 and PDE4, and positive responses in the altered Ca2+ homeostasis to PDE inhibitors as seen in our study can provide important insights about the roles of activated PDEs in depressed contractile activity in hearts from MetS rats.
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Affiliation(s)
- Esma N Okatan
- Department of Biophysics, Ankara University, Faculty of Medicine, 06100 Ankara, Turkey.,Department of Biophysics, Ankara University, Faculty of Medicine, 06100 Ankara, Turkey
| | - Belma Turan
- Department of Biophysics, Ankara University, Faculty of Medicine, 06100 Ankara, Turkey.,Department of Biophysics, Ankara University, Faculty of Medicine, 06100 Ankara, Turkey
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Tuncay E, Olgar Y, Durak A, Degirmenci S, Bitirim CV, Turan B. β 3 -adrenergic receptor activation plays an important role in the depressed myocardial contractility via both elevated levels of cellular free Zn 2+ and reactive nitrogen species. J Cell Physiol 2019; 234:13370-13386. [PMID: 30613975 DOI: 10.1002/jcp.28015] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Accepted: 12/11/2018] [Indexed: 12/27/2022]
Abstract
Role of β3 -AR dysregulation, as either cardio-conserving or cardio-disrupting mediator, remains unknown yet. Therefore, we examined the molecular mechanism of β3 -AR activation in depressed myocardial contractility using a specific agonist CL316243 or using β3 -AR overexpressed cardiomyocytes. Since it has been previously shown a possible correlation between increased cellular free Zn2+ ([Zn2+ ]i ) and depressed cardiac contractility, we first demonstrated a relation between β3 -AR activation and increased [Zn2+ ]i , parallel to the significant depolarization in mitochondrial membrane potential in rat ventricular cardiomyocytes. Furthermore, the increased [Zn2+ ]i induced a significant increase in messenger RNA (mRNA) level of β3 -AR in cardiomyocytes. Either β3 -AR activation or its overexpression could increase cellular reactive oxygen species (ROS) and reactive nitrogen species (RNS) levels, in line with significant changes in nitric oxide (NO)-pathway, including increases in the ratios of pNOS3/NOS3 and pGSK-3β/GSK-3β, and PKG expression level in cardiomyocytes. Although β3 -AR activation induced depression in both Na+ - and Ca2+ -currents, the prolonged action potential (AP) seems to be associated with a marked depression in K+ -currents. The β3 -AR activation caused a negative inotropic effect on the mechanical activity of the heart, through affecting the cellular Ca2+ -handling, including its effect on Ca2+ -leakage from sarcoplasmic reticulum (SR). Our cellular level data with β3 -AR agonism were supported with the data on high [Zn2+ ]i and β3 -AR protein-level in metabolic syndrome (MetS)-rat heart. Overall, our present data can emphasize the important deleterious effect of β3 -AR activation in cardiac remodeling under pathological condition, at least, through a cross-link between β3 -AR activation, NO-signaling, and [Zn2+ ]i pathways. Moreover, it is interesting to note that the recovery in ER-stress markers with β3 -AR agonism in hyperglycemic cardiomyocytes is favored. Therefore, how long and to which level the β3 -AR agonism would be friend or become foe remains to be mystery, yet.
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Affiliation(s)
- Erkan Tuncay
- Department of Biophysics, Ankara University Faculty of Medicine, Ankara, Turkey
| | - Yusuf Olgar
- Department of Biophysics, Ankara University Faculty of Medicine, Ankara, Turkey
| | - Aysegul Durak
- Department of Biophysics, Ankara University Faculty of Medicine, Ankara, Turkey
| | - Sinan Degirmenci
- Department of Biophysics, Ankara University Faculty of Medicine, Ankara, Turkey
| | | | - Belma Turan
- Department of Biophysics, Ankara University Faculty of Medicine, Ankara, Turkey
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11
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Durak A, Olgar Y, Degirmenci S, Akkus E, Tuncay E, Turan B. A SGLT2 inhibitor dapagliflozin suppresses prolonged ventricular-repolarization through augmentation of mitochondrial function in insulin-resistant metabolic syndrome rats. Cardiovasc Diabetol 2018; 17:144. [PMID: 30447687 PMCID: PMC6240275 DOI: 10.1186/s12933-018-0790-0] [Citation(s) in RCA: 93] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 11/14/2018] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Metabolic syndrome (MetS) is a prevalent risk factor for cardiac dysfunction. Although SGLT2-inhibitors have important cardioprotective effects in hyperglycemia, their underlying mechanisms are complex and not completely understood. Therefore, we examined mechanisms of a SGLT2-inhibitor dapagliflozin (DAPA)-related cardioprotection in overweight insulin-resistant MetS-rats comparison with insulin (INSU), behind its glucose-lowering effect. METHODS A 28-week high-carbohydrate diet-induced MetS-rats received DAPA (5 mg/kg), INSU (0.15 mg/kg) or vehicle for 2 weeks. To validate MetS-induction, we monitored all animals weekly by measuring body weight, blood glucose and HOMO-IR index, electrocardiograms, heart rate, systolic and diastolic pressures. RESULTS DAPA-treatment of MetS-rats significantly augmented the increased blood pressure, prolonged Q-R interval, and low heart rate with depressed left ventricular function and relaxation of the aorta. Prolonged-action potentials were preserved with DAPA-treatment, more prominently than INSU-treatment, at most, through the augmentation in depressed voltage-gated K+-channel currents. DAPA, more prominently than INSU-treatment, preserved the depolarized mitochondrial membrane potential, and altered mitochondrial protein levels such as Mfn-1, Mfn-2, and Fis-1 as well as provided significant augmentation in cytosolic Ca2+-homeostasis. Furthermore, DAPA also induced significant augmentation in voltage-gated Na+-currents and intracellular pH, and the cellular levels of increased oxidative stress, protein-thiol oxidation and ADP/ATP ratio in cardiomyocytes from MetS rats. Moreover, DAPA-treatment normalized the increases in the mRNA level of SGLT2 in MetS-rat heart. CONCLUSIONS Overall, our data provided a new insight into DAPA-associated cardioprotection in MetS rats, including suppression of prolonged ventricular-repolarization through augmentation of mitochondrial function and oxidative stress followed by improvement of fusion-fission proteins, out of its glucose-lowering effect.
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Affiliation(s)
- Aysegul Durak
- Departments of Biophysics, Faculty of Medicine, Ankara University, Ankara, Turkey
| | - Yusuf Olgar
- Departments of Biophysics, Faculty of Medicine, Ankara University, Ankara, Turkey
| | - Sinan Degirmenci
- Departments of Biophysics, Faculty of Medicine, Ankara University, Ankara, Turkey
| | - Erman Akkus
- Internal Medicine, Faculty of Medicine, Ankara University, Ankara, Turkey
| | - Erkan Tuncay
- Departments of Biophysics, Faculty of Medicine, Ankara University, Ankara, Turkey
| | - Belma Turan
- Departments of Biophysics, Faculty of Medicine, Ankara University, Ankara, Turkey.
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12
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Olgar Y, Turan B. A sodium-glucose cotransporter 2 (SGLT2) inhibitor dapagliflozin comparison with insulin shows important effects on Zn 2+-transporters in cardiomyocytes from insulin-resistant metabolic syndrome rats through inhibition of oxidative stress 1. Can J Physiol Pharmacol 2018; 97:528-535. [PMID: 30444646 DOI: 10.1139/cjpp-2018-0466] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Sodium-glucose cotransporter 2 (SGLT2) inhibitors showed significant effects in patients with diabetes or metabolic syndrome (MetS) with high cardiovascular risk. Although the increased intracellular Zn2+ level ([Zn2+]i), oxidative stress, and altered cardiac matrix metalloproteinases (MMPs) in diabetic cardiomyopathy can intersect with different signaling pathways, the exact mechanisms are not known yet. Since either MMPs or SGLT2 have important roles in cardiac-fibrosis under hyperglycemia, we aimed to examine the role of SGLT2 inhibitor dapagliflozin (DAP) on cardiac Zn2+-transporters responsible for [Zn2+]i-regulation, comparison to insulin (INS), together with MMP levels and systemic oxidative stress status in MetS-rats. High-carbohydrated diet-induced MetS-rats received DAP or INS for 2 weeks. DAP but not INS in MetS-rats significantly decreased high blood-glucose levels, while both treatments exerted benefits on increased total oxidative status and decreased total antioxidant status in MetS-rat plasma as well as in heart tissue. Protein levels of Zn2+-transporters, responsible for Zn2+-influx into cytosol, ZIP7 and ZIP14 were increased with significant decrease in ZIP8 of MetS-rat cardiomyoctes, while Zn2+-transporters, responsible for cytosolic Zn2+-efflux, ZnT7 was decreased with no change in ZnT8. Both treatments induced significant beneficial effects on altered ZIP14, ZIP8, and ZnT7 levels. Furthermore, both treatments exerted benefits on depressed gelatin-zymography and protein expression levels of MMP-2 and MMP-9 in MetS-rat ventricular cardiomyocytes. The direct effect of DAP on heart was also confirmed with measurements of left ventricular developed pressure. Overall, we showed that DAP has important antioxidant-like cardio-protective effects in MetS-rats, similar to INS-effect, affecting Zn2+-regulation via Zn2+-transporters, MMPs, and oxidative stress. Therefore one can suggest that SGLT2 inhibitors can be new therapeutic agents for cardio-protection not only in hyperglycemia but also in failing heart.
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Affiliation(s)
- Yusuf Olgar
- Departments of Biophysics and Internal Medicine, Faculty of Medicine, Ankara University, Ankara, Turkey.,Departments of Biophysics and Internal Medicine, Faculty of Medicine, Ankara University, Ankara, Turkey
| | - Belma Turan
- Departments of Biophysics and Internal Medicine, Faculty of Medicine, Ankara University, Ankara, Turkey.,Departments of Biophysics and Internal Medicine, Faculty of Medicine, Ankara University, Ankara, Turkey
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13
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Aging related functional and structural changes in the heart and aorta: MitoTEMPO improves aged-cardiovascular performance. Exp Gerontol 2018; 110:172-181. [DOI: 10.1016/j.exger.2018.06.012] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Revised: 05/30/2018] [Accepted: 06/11/2018] [Indexed: 12/19/2022]
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14
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Durak A, Olgar Y, Tuncay E, Karaomerlioglu I, Kayki Mutlu G, Arioglu Inan E, Altan VM, Turan B. Onset of decreased heart work is correlated with increased heart rate and shortened QT interval in high-carbohydrate fed overweight rats. Can J Physiol Pharmacol 2017; 95:1335-1342. [DOI: 10.1139/cjpp-2017-0054] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Mechanical activity of the heart is adversely affected in metabolic syndrome (MetS) characterized by increased body mass and marked insulin resistance. Herein, we examined the effects of high carbohydrate intake on cardiac function abnormalities by evaluating in situ heart work, heart rate, and electrocardiograms (ECGs) in rats. MetS was induced in male Wistar rats by adding 32% sucrose to drinking water for 22–24 weeks and was confirmed by insulin resistance, increased body weight, increased blood glucose and serum insulin, and increased systolic and diastolic blood pressures in addition to significant loss of left ventricular integrity and increased connective tissue around myofibrils. Analysis of in situ ECG recordings showed a markedly shortened QT interval and decreased QRS amplitude with increased heart rate. We also observed increased oxidative stress and decreased antioxidant defense characterized by decreases in serum total thiol level and attenuated paraoxonase and arylesterase activities. Our data indicate that increased heart rate and a shortened QT interval concomitant with higher left ventricular developed pressure in response to β-adrenoreceptor stimulation as a result of less cyclic AMP release could be regarded as a natural compensation mechanism in overweight rats with MetS. In addition to the persistent insulin resistance and obesity associated with MetS, one should consider the decreased heart work, increased heart rate, and shortened QT interval associated with high carbohydrate intake, which may have more deleterious effects on the mammalian heart.
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Affiliation(s)
- Aysegul Durak
- Department of Biophysics, Faculty of Medicine, Ankara University, Ankara, Turkey
| | - Yusuf Olgar
- Department of Biophysics, Faculty of Medicine, Ankara University, Ankara, Turkey
| | - Erkan Tuncay
- Department of Biophysics, Faculty of Medicine, Ankara University, Ankara, Turkey
| | - Irem Karaomerlioglu
- Department of Pharmacology, Faculty of Pharmacy, Ankara University, Ankara, Turkey
| | - Gizem Kayki Mutlu
- Department of Pharmacology, Faculty of Pharmacy, Ankara University, Ankara, Turkey
| | - Ebru Arioglu Inan
- Department of Pharmacology, Faculty of Pharmacy, Ankara University, Ankara, Turkey
| | - Vecdi Melih Altan
- Department of Pharmacology, Faculty of Pharmacy, Ankara University, Ankara, Turkey
| | - Belma Turan
- Department of Biophysics, Faculty of Medicine, Ankara University, Ankara, Turkey
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15
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Thuy TD, Phan NN, Wang CY, Yu HG, Wang SY, Huang PL, Do YY, Lin YC. Novel therapeutic effects of sesamin on diabetes-induced cardiac dysfunction. Mol Med Rep 2017; 15:2949-2956. [PMID: 28358428 PMCID: PMC5428537 DOI: 10.3892/mmr.2017.6420] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Accepted: 10/27/2016] [Indexed: 12/19/2022] Open
Abstract
Diabetes is a risk factor that increases the occurrence and severity of cardiovascular events. Cardiovascular complications are the leading cause of mortality of 75% of patients with diabetes >40 years old. Sesamin, the bioactive compound extracted from Sesamum indicum, is a natural compound that has diverse beneficial effects on hypoglycemia and reducing cholesterol. The aim of this study is to investigate sesamin effects to diabetes-inducing cardiac hypertrophy. In the present study bioinformatics analysis demonstrated cardiac hypertrophy signaling may be the most important pathway for upregulating genes in sesamin-treated groups. To verify the bioinformatics prediction, sesamin was used as the main bioactive compound to attenuate the impact of diabetes induced by streptozotocin (STZ) on cardiac function in a rat model. The results revealed that oral administration of sesamin for 4 weeks (100 and 200 mg/kg body weight) marginally improved blood glucose levels, body weight and significantly ameliorated the effects on heart rate and blood pressure in rats with type 1 diabetes relative to control rats. The QT interval of sesamin was also reduced relative to the control group. The findings indicated that sesamin has potential cardioprotective effects in the STZ-induced diabetes model. This suggested that this can be used as a novel treatment for patients with diabetes with cardiac dysfunction complication.
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Affiliation(s)
- Tran Duong Thuy
- Graduate Institute of Biotechnology, Chinese Culture University, YangMingShan, Taipei 11114, Taiwan, R.O.C
| | - Nam Nhut Phan
- Faculty of Applied Sciences, Ton Duc Thang University, Ho Chi Minh City 70000, Vietnam
| | - Chih-Yang Wang
- Department of Anatomy, University of California San Francisco, San Francisco, CA 94143, USA
| | - Han-Gang Yu
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV 26506, USA
| | - Shu-Yin Wang
- Graduate Institute of Biotechnology, Chinese Culture University, YangMingShan, Taipei 11114, Taiwan, R.O.C
| | - Pung-Ling Huang
- Graduate Institute of Biotechnology, Chinese Culture University, YangMingShan, Taipei 11114, Taiwan, R.O.C
| | - Yi-Yin Do
- Department of Horticulture and Landscape Architecture, National Taiwan University, Taipei 10617, Taiwan, R.O.C
| | - Yen-Chang Lin
- Graduate Institute of Biotechnology, Chinese Culture University, YangMingShan, Taipei 11114, Taiwan, R.O.C
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16
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Okatan EN, Durak AT, Turan B. Electrophysiological basis of metabolic-syndrome-induced cardiac dysfunction. Can J Physiol Pharmacol 2016; 94:1064-1073. [DOI: 10.1139/cjpp-2015-0531] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Myocardial contractility is controlled by intracellular Ca2+ cycling with the contribution of sarcoplasmic reticulum (SR). In this study, we aimed to investigate the role of altered SR function in defective regulation of intracellular Ca2+ levels in rats with metabolic syndrome (MetS) induced by a 16-week high-sucrose drinking-water diet. Electric-field stimulated transient intracellular Ca2+ changes in MetS cardiomyocytes exhibited significantly reduced amplitude (∼30%) and prolonged time courses (2-fold), as well as depressed SR Ca2+ loading (∼55%) with increased basal Ca2+ level. Consistent with these data, altered ryanodine receptor (RyR2) function and SERCA2a activity were found in MetS cardiomyocytes through Ca2+ spark measurements and caffeine application assay in a state in which sodium calcium exchanger was inhibited. Furthermore, tetracaine application assay results and hyperphosphorylated level of RyR2 also support the “leaky RyR2” hypothesis. Moreover, altered phosphorylation levels of phospholamban (PLN) support the depressed SERCA2a-activity thesis and these alterations in the phosphorylation of Ca2+-handling proteins are correlated with altered protein kinase and phosphatase activity in MetS cardiomyocytes. In conclusion, MetS-rat heart exhibits altered Ca2+ signaling largely due to altered SR function via changes in RyR2 and SERCA2a activity. These results point to RyR2 and SERCA2a as potential pharmacological targets for restoring intracellular Ca2+ homeostasis and, thereby, combatting dysfunction in MetS-rat heart.
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Affiliation(s)
- Esma N. Okatan
- Department of Biophysics, Ankara University, Faculty of Medicine, 06100 Ankara, Turkey
- Department of Biophysics, Ankara University, Faculty of Medicine, 06100 Ankara, Turkey
| | - Aysegul Toy Durak
- Department of Biophysics, Ankara University, Faculty of Medicine, 06100 Ankara, Turkey
- Department of Biophysics, Ankara University, Faculty of Medicine, 06100 Ankara, Turkey
| | - Belma Turan
- Department of Biophysics, Ankara University, Faculty of Medicine, 06100 Ankara, Turkey
- Department of Biophysics, Ankara University, Faculty of Medicine, 06100 Ankara, Turkey
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17
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Baczkó I, Jost N, Varró A. Cardioprotection and arrhythmias, Part I. Can J Physiol Pharmacol 2015; 93:v. [PMID: 26444056 DOI: 10.1139/cjpp-2015-0198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- István Baczkó
- a Department of Pharmacology and Pharmacotherapy, University of Szeged, Hungary
| | - Norbert Jost
- b Department of Pharmacology and Pharmacotherapy, University of Szeged, Hungary and MTA-SZTE Research Group of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary
| | - András Varró
- b Department of Pharmacology and Pharmacotherapy, University of Szeged, Hungary and MTA-SZTE Research Group of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary
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