OBJECTIVES: Due to poor treatment adherence and lifestyle-based interventions, chronic hypertension is a dominant risk factor predisposing individuals to heart failure and malignant arrhythmias. We investigated the impact of the postnatal acclimation of hairless SHR to ambient temperature that is, for them, below thermoneutrality, on the electrical coupling protein connexin-43 (Cx43) and pro-fibrotic markers in both heart ventricles of male and female hairless SHR rats compared to the wild SHR. METHODS: Some 6-month-acclimated male and female hairless SHR as well as age- and sex-matched wild SHR were included and compared with the non-hypertensive Wistar strain. The left and right heart ventricles were examined for Cx43 topology, myocardial structure, and the histochemistry of capillaries. The protein levels of Cx43, relevant protein kinases, and extracellular matrix proteins (ECMs) were determined by immunoblotting. MMP-2 activity was assessed via zymography, and susceptibility to malignant arrhythmias was tested ex vivo. RESULTS: Cx43 and its phosphorylated variant pCx43368 were significantly reduced in the left heart ventricles of wild SHR males, while to a lesser extent in the hairless SHR. In contrast, these proteins were not significantly altered in the right heart ventricles of males or in both heart ventricles in females, regardless of the rat strain. Pro-arrhythmic Cx43 topology was detected in the left heart ventricle of wild SHR and to a lesser extent in hairless SHR males. TGFβ protein was significantly increased only in the left ventricle of the wild SHR males. MMP-2 activity was increased in the right ventricle but not in the left ventricles of both males and females, regardless of the rat strain. CONCLUSIONS: The findings indicate that the postnatal acclimation of hairless SHR to ambient temperature hampers the downregulation of Cx43 in the left heart ventricle compared to wild SHR males. The decline of Cx43 was much less pronounced in females and not observed in the right heart ventricles, regardless of the rat strain. It may impact the susceptibility of the heart to malignant arrhythmias.
- Klíčová slova
- arrhythmias, connexin43, females, hairless SHR, left and right heart ventricle, males,
- MeSH
- aklimatizace MeSH
- down regulace MeSH
- hypertenze * metabolismus MeSH
- konexin 43 * metabolismus genetika MeSH
- krysa rodu Rattus MeSH
- potkani inbrední SHR * MeSH
- potkani Wistar MeSH
- srdeční arytmie * metabolismus etiologie MeSH
- srdeční komory * metabolismus MeSH
- teplota * MeSH
- zvířata MeSH
- Check Tag
- krysa rodu Rattus MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- Gja1 protein, rat MeSH Prohlížeč
- konexin 43 * MeSH
A subpopulation of astrocytes on the brain's surface, known as subpial astrocytes, constitutes the "glia limitans superficialis" (GLS), which is an interface between the brain parenchyma and the cerebrospinal fluid (CSF) in the subpial space. Changes in connexin-43 (Cx43) and aquaporin-4 (AQP4) proteins in subpial astrocytes were examined in the medial prefrontal cortex at postoperative day 1, 3, 7, 14, and 21 after sham operation and sciatic nerve compression (SNC). In addition, we tested the altered uptake of TRITC-conjugated 3 kDa dextran by reactive subpial astrocytes. Cellular immunofluorescence (IF) detection and image analysis were used to examine changes in Cx43 and AQP4 protein levels, as well as TRITC-conjugated 3 kDa dextran, in subpial astrocytes. The intensity of Cx43-IF was significantly increased, but AQP4-IF decreased in subpial astrocytes of sham- and SNC-operated rats during all survival periods compared to naïve controls. Similarly, the uptake of 3 kDa dextran in the GLS was reduced following both sham and SNC operations. The results suggest that both sciatic nerve injury and peripheral tissue injury alone can induce changes in subpial astrocytes related to the spread of their reactivity across the cortical surface mediated by increased amounts of gap junctions. At the same time, water transport and solute uptake were impaired in subpial astrocytes.
- Klíčová slova
- aquaporins, astrocytes, fluoro-ruby, gap junction, image analysis, in situ proteomics, nerve injury, reactivity, tissue injury,
- MeSH
- akvaporin 4 * metabolismus MeSH
- astrocyty * metabolismus MeSH
- dextrany * metabolismus MeSH
- konexin 43 * metabolismus MeSH
- krysa rodu Rattus MeSH
- nervus ischiadicus * zranění metabolismus MeSH
- potkani Sprague-Dawley MeSH
- prefrontální mozková kůra * metabolismus MeSH
- zvířata MeSH
- Check Tag
- krysa rodu Rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- akvaporin 4 * MeSH
- Aqp4 protein, rat MeSH Prohlížeč
- dextrany * MeSH
- konexin 43 * MeSH
BACKGROUND: The associations of risk factors with vascular impairment in type 1 diabetes patients seem more complex than that in type 2 diabetes patients. Therefore, we analyzed the associations between traditional and novel cardiovascular risk factors and vascular parameters in individuals with T1D and modifications of these associations according to sex and genetic factors. METHODS: In a cross-sectional study, we analyzed the association of risk factors in T1D individuals younger than 65 years using vascular parameters, such as ankle brachial index (ABI) and toe brachial index (TBI), duplex ultrasound, measuring the presence of plaques in carotid and femoral arteries (Belcaro score) and intima media thickness of carotid arteries (CIMT). We also used photoplethysmography, which measured the interbranch index expressed as the Oliva-Roztocil index (ORI), and analyzed renal parameters, such as urine albumin/creatinine ratio (uACR) and glomerular filtration rate (GFR). We evaluated these associations using multivariate regression analysis, including interactions with sex and the gene for connexin 37 (Cx37) polymorphism (rs1764391). RESULTS: In 235 men and 227 women (mean age 43.6 ± 13.6 years; mean duration of diabetes 22.1 ± 11.3 years), pulse pressure was strongly associated with unfavorable values of most of the vascular parameters under study (ABI, TBI, Belcaro scores, uACR and ORI), whereas plasma lipids, represented by remnant cholesterol (cholesterol - LDL-HDL cholesterol), the atherogenic index of plasma (log (triglycerides/HDL cholesterol) and Lp(a), were associated primarily with renal impairment (uACR, GFR and lipoprotein (a)). Plasma non-HDL cholesterol was not associated with any vascular parameter under study. In contrast to pulse pressure, the associations of lipid factors with kidney and vascular parameters were modified by sex and the Cx37 gene. CONCLUSION: In addition to known information, easily obtainable risk factor, such as pulse pressure, should be considered in individuals with T1D irrespective of sex and genetic background. The associations of plasma lipids with kidney function are complex and associated with sex and genetic factors. The decision of whether pulse pressure, remnant lipoproteins, Lp(a) and other determinants of vascular damage should become treatment targets in T1D should be based on the results of future clinical trials.
- Klíčová slova
- Cardiovascular risk factors, Gene for connexin 37, Sex, Type 1 diabetes mellitus, Vascular parameters,
- MeSH
- diabetes mellitus 1. typu * genetika patofyziologie MeSH
- diabetické angiopatie genetika patofyziologie MeSH
- dospělí MeSH
- fenotyp MeSH
- fotopletysmografie MeSH
- genetická predispozice k nemoci MeSH
- hodnoty glomerulární filtrace MeSH
- intimomediální šíře tepenné stěny MeSH
- lidé středního věku MeSH
- lidé MeSH
- polymorfismus genetický MeSH
- protein alfa 4 mezerového spoje * genetika MeSH
- průřezové studie MeSH
- rizikové faktory kardiovaskulárních chorob MeSH
- sexuální faktory MeSH
- tlakový index kotník-paže MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- gap junction protein alpha 4, human MeSH Prohlížeč
- protein alfa 4 mezerového spoje * MeSH
Throughout the brain, astrocytes form networks mediated by gap junction channels that promote the activity of neuronal ensembles. Although their inputs on neuronal information processing are well established, how molecular gap junction channels shape neuronal network patterns remains unclear. Here, using astroglial connexin-deficient mice, in which astrocytes are disconnected and neuronal bursting patterns are abnormal, we show that astrocyte networks strengthen bursting activity via dynamic regulation of extracellular potassium levels, independently of glutamate homeostasis or metabolic support. Using a facilitation-depression model, we identify neuronal afterhyperpolarization as the key parameter underlying bursting pattern regulation by extracellular potassium in mice with disconnected astrocytes. We confirm this prediction experimentally and reveal that astroglial network control of extracellular potassium sustains neuronal afterhyperpolarization via KCNQ voltage-gated K+ channels. Altogether, these data delineate how astroglial gap junctions mechanistically strengthen neuronal population bursts and point to approaches for controlling aberrant activity in neurological diseases.
- Klíčová slova
- CP: Neuroscience, KCNQ channels, afterhyperpolarization, astrocytes, bursting, connexins, gap junctions, mathematical modeling, networks, potassium,
- MeSH
- akční potenciály fyziologie MeSH
- astrocyty * metabolismus MeSH
- draslík * metabolismus MeSH
- draslíkové kanály KCNQ * metabolismus genetika MeSH
- hipokampus * metabolismus MeSH
- konexiny metabolismus genetika MeSH
- mezerový spoj * metabolismus MeSH
- myši inbrední C57BL MeSH
- myši knockoutované MeSH
- myši MeSH
- nervová síť metabolismus MeSH
- neurony metabolismus MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- myši MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- draslík * MeSH
- draslíkové kanály KCNQ * MeSH
- konexiny MeSH
Heart failure (HF) is life-threatening disease due to electro-mechanical dysfunction associated with hemodynamic overload, while alterations of extracellular matrix (ECM) along with perturbed connexin-43 (Cx43) might be key factors involved. We aimed to explore a dual impact of pressure, and volume overload due to aorto-caval fistula (ACF) on Cx43 and ECM as well as effect of renin-angiotensin blockade. Hypertensive Ren-2 transgenic rats (TGR) and normotensive Hannover Sprague-Dawley rats (HSD) that underwent ACF were treated for 15-weeks with trandolapril or losartan. Blood serum and heart tissue samples of the right (RV) and left ventricles (LV) were used for analyses. ACF-HF increased RV, LV and lung mass in HSD and to lesser extent in TGR, while treatment attenuated it and normalized serum ANP, BNP-45 and TBARS. Cx43 protein and its ser368 variant along with PKCε were lower in TGR vs HSD and suppressed in both rat strains due to ACF but prevented more by trandolapril. Pro-hypertrophic PKCδ, collagen I and hydroxyproline were elevated in TGR and increased due to ACF in both rat strains. While SMAD2/3 and MMP2 levels were lower in TGR vs HSD and reduced due to ACF in both strains. Findings point out the strain-related differences in response to volume overload. Disorders of Cx43 and ECM signalling may contribute not only to HF but also to the formation of arrhythmogenic substrate. There is benefit of treatment with trandolapril and losartan indicating their pleiotropic anti-arrhythmic potential. It may provide novel input to therapy.
- MeSH
- extracelulární matrix MeSH
- hypertenze * MeSH
- konexin 43 genetika MeSH
- krevní tlak MeSH
- krysa rodu Rattus MeSH
- losartan farmakologie MeSH
- píštěle * MeSH
- potkani Sprague-Dawley MeSH
- potkani transgenní MeSH
- renin MeSH
- srdeční selhání * MeSH
- zvířata MeSH
- Check Tag
- krysa rodu Rattus MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- konexin 43 MeSH
- losartan MeSH
- renin MeSH
- trandolapril MeSH Prohlížeč
Melatonin has been reported to cause myocardial electrophysiological changes and prevent ventricular tachycardia or fibrillation (VT/VF) in ischemia and reperfusion. We sought to identify electrophysiological targets responsible for the melatonin antiarrhythmic action and to explore whether melatonin receptor-dependent pathways or its antioxidative properties are essential for these effects. Ischemia was induced in anesthetized rats given a placebo, melatonin, and/or luzindole (MT1/MT2 melatonin receptor blocker), and epicardial mapping with reperfusion VT/VFs assessment was performed. The oxidative stress assessment and Western blotting analysis were performed in the explanted hearts. Transmembrane potentials and ionic currents were recorded in cardiomyocytes with melatonin and/or luzindole application. Melatonin reduced reperfusion VT/VF incidence associated with local activation time in logistic regression analysis. Melatonin prevented ischemia-related conduction slowing and did not change the total connexin43 (Cx43) level or oxidative stress markers, but it increased the content of a phosphorylated Cx43 variant (P-Cx43368). Luzindole abolished the melatonin antiarrhythmic effect, slowed conduction, decreased total Cx43, protein kinase Cε and P-Cx43368 levels, and the IK1 current, and caused resting membrane potential (RMP) depolarization. Neither melatonin nor luzindole modified INa current. Thus, the antiarrhythmic effect of melatonin was mediated by the receptor-dependent enhancement of impulse conduction, which was associated with Cx43 phosphorylation and maintaining the RMP level.
- Klíčová slova
- conduction velocity, connexin-43, melatonin, post-ischemic arrhythmias, potassium current, rat heart, sodium current,
- MeSH
- antiarytmika farmakologie terapeutické užití MeSH
- kardiomyocyty metabolismus MeSH
- konexin 43 * metabolismus MeSH
- krysa rodu Rattus MeSH
- melatonin * farmakologie terapeutické užití MeSH
- melatoninové receptory metabolismus MeSH
- srdeční arytmie farmakoterapie prevence a kontrola MeSH
- zvířata MeSH
- Check Tag
- krysa rodu Rattus MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- antiarytmika MeSH
- konexin 43 * MeSH
- luzindole MeSH Prohlížeč
- melatonin * MeSH
- melatoninové receptory MeSH
Our and other studies suggest that myocardial hypertrophy in response to hypertension and hyperthyroidism increases propensity of the heart to malignant arrhythmias, while these are rare in conditions of hypothyroidism or type-1 diabetes mellitus associated with myocardial atrophy. One of the crucial factors impacting the susceptibility of the heart to life-threatening arrhythmias is gap junction channel protein connexin-43 (Cx43), which ensure cell-to-cell coupling for electrical signal propagation. Therefore, we aimed to explore Cx43 protein abundance and its topology in hypertrophic and hypotrophic cardiac phenotype. Analysis were performed in left ventricular tissue of adult male spontaneously hypertensive rat (SHR), Wistar Kyoto rats treated for 8-weeks with L-thyroxine, methimazol or strepotozotocin to induce hyperthyroid, hypothyroid and type-1 diabetic status as well as non-treated animals. Results showed that comparing to healthy rats there was a decrease of total myocardial Cx43 and its variant phosphorylated at serine368 in SHR and hyperthyroid rats. Besides, enhanced localization of Cx43 was demonstrated on lateral sides of hypertrophied cardiomyocytes. In contrast, total Cx43 protein and its serine368 variant were increased in atrophied left ventricle of hypothyroid and type-1 diabetic rats. It was associated with less pronounced alterations in Cx43 topology. In parallel, the abundance of PKCepsilon, which phosphorylates Cx43 at serine368 that stabilize Cx43 function and distribution was reduced in hypertrophied heart while enhanced in atrophied once. Findings suggest that differences in the abundance of cardiac Cx43, its variant phosphorylated at serine368 and Cx43 topology may explain, in part, distinct propensity of hypertrophied and atrophied heart to malignant arrhythmias.
- MeSH
- atrofie patologie MeSH
- diabetes mellitus 1. typu * metabolismus MeSH
- experimentální diabetes mellitus * metabolismus MeSH
- hypertrofie metabolismus MeSH
- hypertyreóza * komplikace metabolismus MeSH
- hypotyreóza * metabolismus MeSH
- konexin 43 metabolismus MeSH
- konexiny MeSH
- krysa rodu Rattus MeSH
- myokard metabolismus MeSH
- pilotní projekty MeSH
- potkani inbrední SHR MeSH
- potkani inbrední WKY MeSH
- srdeční arytmie patologie MeSH
- zvířata MeSH
- Check Tag
- krysa rodu Rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- konexin 43 MeSH
- konexiny MeSH
The extracellular matrix (ECM) is a highly dynamic structure controlling the proper functioning of heart muscle. ECM remodeling with enhanced collagen deposition due to hemodynamic overload impairs cardiomyocyte adhesion and electrical coupling that contributes to cardiac mechanical dysfunction and arrhythmias. We aimed to explore ECM and connexin-43 (Cx43) signaling pathways in hemodynamically overloaded rat heart as well as the possible implication of angiotensin (1-7) (Ang (1-7)) to prevent/attenuate adverse myocardial remodeling. Male 8-week-old, normotensive Hannover Spraque-Dawley rats (HSD), hypertensive (mRen-2)27 transgenic rats (TGR) and Ang (1-7) transgenic rats (TGR(A1-7)3292) underwent aortocaval fistula (ACF) to produce volume overload. Five weeks later, biometric and heart tissue analyses were performed. Cardiac hypertrophy in response to volume overload was significantly less pronounced in TGR(A1-7)3292 compared to HSD rats. Moreover, a marker of fibrosis hydroxyproline was increased in both ventricles of volume-overloaded TGR while it was reduced in the Ang (1-7) right heart ventricle. The protein level and activity of MMP-2 were reduced in both ventricles of volume-overloaded TGR/TGR(A1-7)3292 compared to HSD. SMAD2/3 protein levels were decreased in the right ventricle of TGR(A1-7)3292 compared to HSD/TGR in response to volume overload. In parallel, Cx43 and pCx43 implicated in electrical coupling were increased in TGR(A1-7)3292 versus HSD/TGR. It can be concluded that Ang (1-7) exhibits cardio-protective and anti-fibrotic potential in conditions of cardiac volume overload.
- Klíčová slova
- angiotensin (1-7), aortocaval fistula, connexin 43, extracellular matrix, heart failure,
- MeSH
- angiotensin II MeSH
- fibróza MeSH
- hypertenze * metabolismus MeSH
- konexin 43 MeSH
- krysa rodu Rattus MeSH
- potkani transgenní MeSH
- srdce MeSH
- srdeční selhání * MeSH
- zvířata MeSH
- Check Tag
- krysa rodu Rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- angiotensin I (1-7) MeSH Prohlížeč
- angiotensin II MeSH
- konexin 43 MeSH
Melatonin treatment was reported to reduce the risk of cardiac arrhythmias, and crucial for this antiarrhythmic action was the effect of melatonin on activation spread. The aim of the present study was evaluation of the mechanisms of this activation enhancement. Experiments were performed in a total of 123 control and melatonin-treated (10 mg/kg, daily, for 7 days) male Wistar rats. In epicardial mapping studies (64 leads, interlead distance 0.5 mm) in the anesthetized animals, activation times (ATs) were determined in each lead as dV/dt minimum during QRS complex under sinus rhythm. Epicardial pacing was performed to measure conduction velocity (CV) across the mapped area. Average left ventricular ATs were shorter in the treated animals as compared to the controls, whereas the minimal epicardial ATs indicating the duration of activation propagation via the ventricular conduction system did not differ between the groups. CV was higher in the treated groups indicating that melatonin affected conduction via contractile myocardium The area of Cx43-derived fluorescence, as well as the expression of Cx43 protein, was similar in ventricles in the control and melatonin-treated groups. Expression of Gja1 gene transcripts encoding Cx43, was increased in the last group. An uncoupling agent octanol modified myocardial conduction properties (time of activation, action potential upstroke velocity, passive electrotonic phase duration) similarly in both groups. On the other hand, the expression of both Scn5a gene transcripts encoding Nav1.5 proteins, as well as peak density of transmembrane sodium current were increased in the ventricular myocytes from the melatonin-treated animals. Thus, a week-long melatonin treatment caused the increase of conduction velocity via enhancement of sodium channel proteins expression and increase of sodium current in the ventricular myocytes.
- Klíčová slova
- conduction velocity, connexins, melatonin, sodium channels, sodium current,
- MeSH
- konexin 43 * genetika MeSH
- krysa rodu Rattus MeSH
- melatonin * farmakologie MeSH
- napěťově řízený sodíkový kanál, typ 5 * genetika MeSH
- potkani Wistar MeSH
- převodní systém srdeční * účinky léků MeSH
- sodík MeSH
- srdce fyziologie MeSH
- upregulace MeSH
- zvířata MeSH
- Check Tag
- krysa rodu Rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- konexin 43 * MeSH
- melatonin * MeSH
- napěťově řízený sodíkový kanál, typ 5 * MeSH
- Scn5a protein, rat MeSH Prohlížeč
- sodík MeSH
The frequencies of adverse outcomes associated with male reproductive health, including infertility and testicular cancer, are increasing. These adverse trends are partially attributed to increased exposure to environmental agents such as endocrine-disrupting chemicals (EDCs). This study addresses effects on EDCs on adjacent prepubertal Sertoli TM4 cells, specifically on 1) testicular gap junctional intercellular communication (GJIC), one of the hallmarks of non-genotoxic carcinogenicity, 2) GJIC building blocks connexins (Cx), and 3) mitogen-activated protein kinases MAPKs. We selected eight representatives of EDCs: organochlorine chemicals such as pesticides dichlorodiphenyltrichloroethane, lindane, methoxychlor, and vinclozolin, industrial chemicals bisphenol A and 2,2',4,4',5,5'-hexachlorobiphenyl, and components of personal care products, triclocarban and triclosan. EDCs rapidly dysregulated GJIC in Sertoli TM4 cells mainly via MAPK p38 and/or Erk1/2 pathways by the intermediate hyper- or de-phosphorylation of Cx43 (Ser368, Ser282) and translocation of Cx43 from the plasma membrane, suggesting disturbed intracellular trafficking of Cx43 protein. Surprisingly, EDCs did not rapidly activate MAPK Erk1/2 or p38; on the contrary, TCC and TCS decreased their activity (phosphorylation). Our results indicate that EDCs might disrupt testicular homeostasis and development via testicular GJIC, junctional and non-junctional functions of Cx43 and MAPK-signaling pathways in Sertoli cells.
- Klíčová slova
- Connexins, Endocrine-disrupting chemicals, Gap junctional intercellular communication, Reproductive toxicity, Sertoli cells, Testicular tumors,
- MeSH
- endokrinní disruptory * metabolismus MeSH
- fosforylace MeSH
- konexin 43 genetika metabolismus MeSH
- lidé MeSH
- mezerový spoj metabolismus MeSH
- mezibuněčná komunikace MeSH
- testikulární nádory * metabolismus MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- endokrinní disruptory * MeSH
- konexin 43 MeSH
