Takotsubo cardiomyopathy and pituitary apoplexy: a case report.

BACKGROUND: Takotsubo cardiomyopathy (TTC) has been widely recognized in recent decades and is triggered by either physical or psychological stressors. CASE PRESENTATION: A 70-year-old woman presented to the Emergency Department due to confusion, hypotension, fever, chills, and cough. She had a one-year history of diabetes insipidus. Pituitary function examination at admission revealed decreased thyroid, sex and adrenal hormones. Pituitary MRI displayed findings suggestive of nonhemorrhagic pituitary apoplexy. Electrocardiogram (ECG) revealed T-wave inversion and extended QT interval. Transthoracic echocardiogram (TTE) showed left ventricular apical dysplasia and ballooning, accompanied by reduced left ventricular ejection fraction. Coronary angiography (CAG) revealed no obvious coronary arterial stenosis. The left ventriculogram demonstrated an octopus clathrate appearance. Most ECG and TTE changes recovered 10 days later. CONCLUSIONS: To the best of our knowledge, this is the first report of newly diagnosed TTC associated with pituitary apoplexy.

Correction to: Cardiac rupture complicating acute myocardial infarction: the clinical features from an observational study and animal experiment.

An amendment to this paper has been published and can be accessed via the original article.

Cardiac rupture complicating acute myocardial infarction: the clinical features from an observational study and animal experiment.

BACKGROUND: Cardiac rupture (CR) is a fatal complication of ST-elevation myocardial infarction (STEMI) with its incidence markedly declined in the recent decades. However, clinical features of CR patients now and the effect of reperfusion therapy to CR remain unclear. We investigated the clinical features of CR in STEMI patients and the effect of reperfusion therapy to CR in mice. METHODS: Two studies were conducted. In clinical study, data of 1456 STEMI patients admitted to the First Hospital, Xi'an Jiaotong University during 2015.12. ~ 2018.12. were analyzed. In experimental study, 83 male C57BL/6 mice were operated to induce MI. Of them, 39 mice were permanent MI (group-1), and remaining mice received reperfusion after 1 h ischemia (21 mice, group-2) or 4 h ischemia (23 mice, group-3). All operated mice were monitored up to day-10. Animals were inspected three times daily for the incidence of death and autopsy was done for all mice found died to determine the cause of death. RESULTS: CR was diagnosed in 40 patients: free-wall rupture in 17, ventricular septal rupture in 20, and combined locations in 3 cases. CR presented in 19 patients at admission and diagnosed in another 21 patients during 1 ~ 14 days post-STEMI, giving an in-hospital incidence of 1.4%. The mortality of CR patients was high during hospitalization accounting for 39% of total in-hospital death. By multivariate logistic regression analysis, older age, peak CK-MB and peak hs-CRP were independent predictors of CR post-STEMI. In mice with non-reperfused MI, 17 animals (43.6%) died of CR that occurred during 3-6 days post-MI. In MI mice received early or delayed reperfusion, all mice survived to the end of experiment except one mouse died of acute heart failure. CONCLUSION: CR remains as a major cause of in-hospital death in STEMI patients. CR patients are characterized of being elderly, having larger infarct and more server inflammation. Experimentally, reperfusion post-MI prevented CR.

Resistin may be an independent predictor of subclinical atherosclerosis formale smokers.

To investigate whether resistin is associated with early atherosclerosis in male smokers. The present study consecutively enrolled 50 male smokers. Their serum resistin contents were detected with enzyme linked immunosorbent assay (ELISA), and subclinical atherosclerosis indices, including carotid inner middle thickness (IMT) and arterial elasticity indices (C1 and C2), were measured. The association between serum resistin levels and IMT, C1 and C2 were respectively evaluated with the Pearson's correlation coefficient method. The results showed that the serum resistin level had a positive association with IMT (r = 0.307, p = .030), but were both inversely associated with C1 (r = -0.440, p = .001) and C2 (r = -0.381, p = .006). These associations remained significant even after adjustment for cardiovascular confounders. In conclusion, serum resistin concentration was independently associated with early atherosclerosis in male smokers.

Ultra-high pressure liquid chromatography-tandem mass spectrometry method for the determination of omarigliptin in rat plasma and its application to a pharmacokinetic study in rats.

Omarigliptin is a novel long-acting dipeptidyl peptidase-4 inhibitor used for the treatment of type 2 diabetes. In this work, a sensitive and selective ultra-high pressure liquid chromatography tandem mass spectrometry method was developed and validated for the determination of omarigliptin in rat plasma. Sample preparation was performed by protein precipitation with acetonitrile. Chromatographic separation of analytes was achieved on an RRHD Eclipse Plus C18 column (2.1 × 50 mm, 1.8 µm), using gradient mobile phase (0.1% formic acid-acetonitrile) at a flow rate of 0.4 mL/min. Detection was performed in multiple reaction monitoring mode, with target fragment ions m/z 399.1 → 152.9 for omarigliptin and m/z 237.1 → 194 for the internal standard. The total run time was 4 min. Retention time of omarigliptin and internal standard was 1.25 and 2.12 min, respectively. Relative standard deviation (%) of the intra- and inter-day precision was below 10.0%, and accuracy was between 97.9% and 105.3%. Calibration curve was established over the range 2-5000 ng/mL with good linearity. The lower limit of quantification and limit of detection of omarigliptin were 2 and 0.25 ng/mL, respectively. Mean recoveries were in the range 87.3-95.1% for omarigliptin. No matrix effect was observed in this method. This novel method has been successfully applied to a pharmacokinetic study of omarigliptin in rats. The absolute bioavailability of omarigliptin was identified as high as 87.31%.

Antioxidant catalase rescues against high fat diet-induced cardiac dysfunction via an IKKß-AMPK-dependent regulation of autophagy.

Autophagy, a conservative degradation process for long-lived and damaged proteins, participates in a variety of biological processes including obesity. However, the precise mechanism of action behind obesity-induced changes in autophagy still remains elusive. This study was designed to examine the role of the antioxidant catalase in high fat diet-induced changes in cardiac geometry and function as well as the underlying mechanism of action involved with a focus on autophagy. Wild-type (WT) and transgenic mice with cardiac overexpression of catalase were fed low or high fat diet for 20 weeks prior to assessment of myocardial geometry and function. High fat diet intake triggered obesity, hyperinsulinemia, and hypertriglyceridemia, the effects of which were unaffected by catalase transgene. Myocardial geometry and function were compromised with fat diet intake as manifested by cardiac hypertrophy, enlarged left ventricular end systolic and diastolic diameters, fractional shortening, cardiomyocyte contractile capacity and intracellular Ca²âº mishandling, the effects of which were ameliorated by catalase. High fat diet intake promoted reactive oxygen species production and suppressed autophagy in the heart, the effects of which were attenuated by catalase. High fat diet intake dampened phosphorylation of inhibitor kappa B kinase ß(IKKß), AMP-activated protein kinase (AMPK) and tuberous sclerosis 2 (TSC2) while promoting phosphorylation of mTOR, the effects of which were ablated by catalase. In vitro study revealed that palmitic acid compromised cardiomyocyte autophagy and contractile function in a manner reminiscent of fat diet intake, the effect of which was significantly alleviated by inhibition of IKKß, activation of AMPK and induction of autophagy. Taken together, our data revealed that the antioxidant catalase counteracts against high fat diet-induced cardiac geometric and functional anomalies possibly via an IKKß-AMPK-dependent restoration of myocardial autophagy. This article is part of a Special Issue entitled: Autophagy and protein quality control in cardiometabolic diseases.

Isoproterenol instigates cardiomyocyte apoptosis and heart failure via AMPK inactivation-mediated endoplasmic reticulum stress.

A prolonged or excessive adrenergic activation leads to myocyte loss and heart dysfunction; however, how it contributes to heart failure remains poorly defined. Here we show that isoproterenol (ISO) induced aberrant endoplasmic reticulum (ER) stress and apoptotic cell death, which was inhibited by activating the AMP-activated protein kinase (AMPK) in vitro and in vivo. Persistent ISO stimulation suppressed the AMPK phosphorylation and function, resulting in enhanced ER stress and the subsequent cell apoptosis in cardiomyocytes in vitro and in vivo. AMPK activation decreased the aberrant ER stress, apoptosis, and brain natriuretic peptide (BNP) release in ISO-treated cardiomyocytes, which was blocked by AMPK inhibitor Compound C. Importantly, increased ER stress and apoptosis were observed in ISO-treated cardiomyocytes isolated from AMPKα2(-/-) mice. Inhibition of ER stress attenuated the apoptosis but failed to reverse AMPK inhibition in ISO-treated cardiomyocytes. Moreover, metformin administration activated AMPK and reduced both ER stress and apoptosis in ISO-induced rat heart failure in vivo. We conclude that ISO, via AMPK inactivation, causes aberrant ER stress, cardiomyocyte injury, BNP release, apoptosis, and hence heart failure in vivo, all of which are inhibited by AMPK activation.

Atorvastatin attenuates bleomycin-induced pulmonary fibrosis via suppressing iNOS expression and the CTGF (CCN2)/ERK signaling pathway.

Pulmonary fibrosis is a progressive and fatal lung disorder with high mortality rate. To date, despite the fact that extensive research trials are ongoing, pulmonary fibrosis continues to have a poor response to available medical therapy. Statins, 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors, known for its broad pharmacological activities, remains a remedy against multiple diseases. The present study investigated the antifibrotic potential of atorvastatin against bleomycin-induced lung fibrosis and to further explore the possible underlying mechanisms. Our results showed that atorvastatin administration significantly ameliorated the bleomycin mediated histological alterations and blocked collagen deposition with parallel reduction in the hydroxyproline level. Atorvastatin reduced malondialdehyde (MDA) level and lung indices. Atorvastatin also markedly decreased the expression of inducible nitric oxide synthase (iNOS) in lung tissues and, thus, prevented nitric oxide (NO) release in response to bleomycin challenge. Furthermore, atorvastatin exhibited target down-regulation of connective tissue growth factor (CTGF (CCN2)) and phosphorylation extracellular regulated protein kinases (p-ERK) expression. Taken together, atorvastatin significantly ameliorated bleomycin-induced pulmonary fibrosis in rats, via the inhibition of iNOS expression and the CTGF (CCN2)/ERK signaling pathway. The present study provides evidence that atorvastatin may be a potential therapeutic reagent for the treatment of lung fibrosis.

[Site-directed mutagenesis and protein expression of SCN5A gene associated with congenital long QT syndrome].

OBJECTIVE: To construct the sodium channel gene SCN5A-delQKP1507-1509 mutation associated with congenital long QT syndrome, and its eukaryotic expression vector, and to examine the expression of mutation protein in human embryonic kidney (HEK) 293 cells. METHODS: Eukaryotic expression vector PEGFP-delQKP-hH1 for SCN5A-delQKP1507-1509 mutation was constructed by rapid site-directed mutagenesis. HEK293 cells were transfected with the wild or mutant vector using lipofectamine, and then subjected to confocal microscopy. The transfected cells were immunostained to visualize intracellular expression of the mutant molecules. RESULTS: Direct sequence and electrophoresis analysis revealed 9 basic group absences at position 1507-1509. The delQKP1507-1509 mutation eukaryotic expression vector was expressed in HEK293 cells. Immunostaining of transfected cells showed the expression of both wild type and mutant molecules on the plasma membrane and there was no difference in the amount of protein, which suggested that the mutant delQKP1507-1509 did not impair normal protein expression in HEK293 cells. CONCLUSIONS: Successful construction of mutant SCN5AdelQKP1507-1509 eukaryotic expression vector and expression of SCN5A protein in HEK293 cells provides a basis for further study on the functional effects of congenital long QT syndrome as a cause of SCN5A mutation.

Mesenchymal stem cells neither fully acquire the electrophysiological properties of mature cardiomyocytes nor promote ventricular arrhythmias in infarcted rats.

Electrophysiological properties of implanted mesenchymal stem cells (MSCs) in infarcted hearts remain unclear, and their proarrhythmic effect is still controversial. The intent of this study was to investigate electrophysiological properties and proarrhythmic effects of MSCs in infarcted hearts. Rats were randomly divided into a myocardial infarction (MI) group, a MI-DMEM group (received DMEM medium injection) and MI-MSCs group (received MSCs injection). Survival analysis showed that the majority of engrafted MSCs died at day 9 after transplantation. Engrafted MSCs expressed cardiac markers (MYH, cTnI, Cx43), cardiac ion channel genes (Kv1.4, Kv4.2 and Kir2.1) and potassium currents (I (to), I (K1) and I (KDR)), but did not express Nav1.5, Cav1.2, Na(+) current and Ca(2+) current during their survival. When induced by Ca(2+), implanted MSCs exhibited no contraction ability after being isolated from the heart. Following 8-week electrocardiography monitoring, the cumulative occurrence of ventricular arrhythmias (VAs) was not different among the three groups. However, the prolonged QRS duration in infarcted rats without VAs was significantly decreased in the MI-MSCs group compared with the other two groups. The inducibility of VAs in the MI-MSCs group was much lower than that in the MI and MI-DMEM groups (41.20 vs. 86.67 % and 92.86 %; P < 0.0125). The ventricular effective refractory period in MI-MSCs group was prolonged in comparison with that in the MI and MI-DMEM groups (56.0 ± 8.8 vs. 47.7 ± 8.8 ms and 45.7 ± 6.2 ms; P < 0.01). These results demonstrate that MSCs do not acquire the electrophysiological properties of mature cardiomyocytes during the survival period in the infarcted hearts. However, they can alleviate the electrical vulnerability and do not promote ventricular arrhythmias.

[Association between paraoxonase concentration and risk of acute coronary syndrome].

OBJECTIVE: To investigate the relationship between paraoxonase (PON) concentration and the risk of acute coronary syndrome (ACS). METHODS: The levels of serum PON were detected by enzyme-linked immunosorbent assay in 229 patients with confirmed ACS and 129 control subjects without CHD. Logistic regression analysis and receiver operating characteristic (ROC) curve analysis were applied to analyze the association between PON and ACS. RESULTS: PON was significantly lower in ACS group than in control group [lgPON: (5.72 ± 0.73) ng/L vs. (5.07 ± 0.57) ng/L, P < 0.05]. Logistic regression analysis showed that the level of PON was an independent risk factor of ACS (regression coefficient was -1.793 in univariate logistic regression, OR = 0.166, 95%CI: 0.088 - 0.316; -0.779 in multivariate logistic regression, OR = 0.459, 95%CI: 0.222 - 0.949). ROC analysis showed that the optimal diagnostic cut-off point of PON for ACS was 180 mg/L (sensitivity: 83.3%, specificity: 71.2%). Multiple stepwise regression analysis revealed that there was no significant correlation between lgPON and Gensini score in ACS patients. CONCLUSION: Lower PON is linked with increased risk of ACS, but does not relate with the severity of coronary stenosis.

Histone deacetylase 3 suppresses the expression of SHP-1 via deacetylation of DNMT1 to promote heart failure.

AIMS: Heart failure (HF) is a progressive disease with recurrent hospitalizations and high mortality. However, the mechanisms underlying HF remain unclear. The present study aimed to explore the regulatory mechanism of histone deacetylase 3 (HDAC3) and DNA methyltransferase 1 (DNMT1)/Src homology domain 2-containing tyrosine phosphatase-1 (SHP-1) axis in HF. METHODS: The HF rat models and hypertrophy cell models were established. The characteristic parameters of the heart were detected by echocardiography. A multichannel physiological signal acquisition system was used to detect the hemodynamic parameters. Real-time quantitative polymerase chain reaction (RT-qPCR) was used to detect the expression of HDAC3, DNMT1, and SHP-1 mRNAs, while Western blot was applied to analyze the expression of proteins. Masson staining was used to analyze the degree of collagen fiber infiltration. TdT-mediated DUTP nick end labeling (TUNEL) staining was performed to analyze the apoptosis of myocardial tissue cells. Co-immunoprecipitation (co-IP) was conducted to study the interaction between HDAC3 and DNMT1. Flow cytometry was used to analyze the apoptosis. KEY FINDINGS: HDAC3 and DNMT1 were highly expressed in HF rat and hypertrophy cell models. HDAC3 modified DNMT1 through deacetylation to inhibit ubiquitination-mediated degradation, which promoted the expression of DNMT1. DNMT1 inhibited SHP-1 expression via methylation in the promoter region. In summary, HDAC3 modified DNMT1 by deacetylation to suppress SHP-1 expression, which in turn led to the development of cardiomyocyte hypertrophy-induced HF. SIGNIFICANCE: This study provided potential therapeutic targets for HF treatment.

The Diagnostic and Prognostic Value of Plasma Galectin 3 in HFrEF Related to the Etiology of Heart Failure.

Aim: The aim of present study is to evaluate the diagnostic and prognostic value of plasma galectin 3 (Gal-3) for HF originating from different causes. Methods: We investigated the plasma levels and expression of Gal-3 in cardiac tissues in two transgenic (TG) strains of mice with cardiomyocyte-restricted overexpression of either ß2- adrenergic receptor (ß2- AR TG) or Mammalian sterile 20-like kinase 1 (Mst1-TG) in the present study. Additionally, 166 patients suffering from heart failure with reduced ejection fraction (HFrEF) in two hospitals within the Shaanxi province were examined in this study. All these patients were treated according to the Chinese HF guidelines of 2014; subsequently, they were followed up for 50 months, and we analyzed the prediction value of baseline Gal-3 to endpoints in these patients. Results: Gal-3 was localized in the cytoplasm and nucleus of cardiomyocytes, often formed aggregates in Mst1-TG mice. Extracellular Gal-3 staining was uncommon in Mst1-TG hearts. However, in ß2-AR TG mice, although Gal-3 was also expressed in myocardial cells, it was more highly expressed in interstitial cells (e.g., fibroblasts and macrophages). Plasma Gal-3 was comparable between nTG and Mst1-TG mice. However, plasma Gal-3 was higher in ß2-AR TG mice than in nTG mice. In the cohort of HFrEF patients, the median plasma Gal-3 concentration was 158.42 pg/mL. All participants were divided into two groups according to Gal-3 levels. Patients with Gal-3 concentrations above the median were older, and had lower plasma hemoglobin, but higher plasma creatinine, tissue inhibitor of metalloproteinases 1 (TIMP-1), left ventricular end systolic diameter (LVESD), left ventricular end-systolic volumes (LVESV) and end-diastolic, as well as left ventricular end-diastolic volumes (LVEDV). Spearman correlation analysis revealed that Gal-3 was positively correlated with TIMP-1 (r = 0.396, P < 0.001), LVESV (r = 0.181, P = 0.020) and LVEDV (r = 0.190, P = 0.015). The 50-month clinical follow-up revealed 43 deaths, 97 unplanned re-hospitalizations, and 111 composite endpoint events. Cox analysis demonstrated that although Gal-3 did not provide any prognostic value in either total-HF subjects or coronary-heart-disease (CHD) patients, it did provide prognostic value in non-CHD patients. Conclusion: Although plasma Gal-3 is associated with TIMP-1 and echocardiographic parameters, the diagnostic and prognostic value of Gal-3 in HFrEF is determined by the etiology of HF.

Role of prostaglandin E and its receptors in the process of ductus arteriosus maturation and functional closure in the rabbit.

1. Patent ductus arteriosus (PDA) is a common congenital heart defect in premature infants. The present study was designed to determine the role of the prostaglandin (PG) E(2) pathway in the process of ductus arteriosus (DA) maturation and functional closure. 2. Changes in PGE(2) pathway-related enzymes and receptors in DA in preterm and term rabbits were examined at both the mRNA and protein levels. In addition, responses of DA rings to Po(2) and PGE(2) were determined. 3. Circulating PGE(2) levels remained high until 2 h after birth. High levels of the EP(4) receptor were found in preterm DA. These tissues were sensitive to PGE(2), which caused vessel dilation, but were insensitive to increased Po(2). In contrast, DA tissues from term rabbits exhibited an immediate contractile response to increased Po(2) and PGE(2) treatment resulted in vasoconstriction, which was associated with increased EP(3) and decreased EP(4) receptor expression in term DA. 4. In conclusion, the preterm PDA is maintained by high levels of PGE(2), which mainly binds to the EP(4) receptor under conditions of hypoxia. In contrast, in the term DA, in which levels of the EP(3) receptor are higher than in preterm DA, exposure to PGE(2) resulted in vasoconstriction under normoxic conditions. These findings suggest that blocking the EP(4) receptor may represent a more selective treatment for the preterm PDA, whereas activating the EP(3) receptor may be more suitable for the treatment of the term PDA.

[Linkage analysis and gene mapping of one Chinese family with benign familial infantile convulsions].

OBJECTIVE: The present study performed linkage analysis and gene mapping to find the possible chromosome locus harboring in one family with benign familial infantile convulsions (BFIC) and investigate the possible molecular pathogenesis of BFIC. METHODS: A four-generation family with BFIC was investigated. The family was genotyped using eight hypervariable microsatellite markers covering four loci: D19S245 and D19S250 for the 19q12-13.1 region, D16S3131 and D16S3133 for the 16p12-q12 region, D2S156 and D2S286 for the 2q24 region, and D20S480 and D20S481 for the 20q13.3 region. Polymorphism fragments were amplified using polymerase chain reaction (PCR) method. PCR products for the markers were subjected to electrophoresis on 8% denatured polyacrylamide gel and silver staining for length judgment of amplification fragment. Linkage analysis was performed by use of MLINK in the LINKAGE computer package. Two-point LOD scores were calculated to estimate the linkage relationship. RESULTS: The two-point LOD scores were less than -2.0 for the genetic markers at chromosomes 19q12-13.1, 16p12-q12 and 2q24 at the recombination rate between 0.000 and 0.01. The two-point LOD scores for D20S481 at the 20q13.3 region were 0.3 and 0.25 at the recombination rate of 0.000 and 0.01, respectively. CONCLUSIONS: There is no evidence that this family with BFIC is linked to one of the following loci: 19q12-13.1, 16p12-q12 and 2q24, but a possible linkage with 20q13.3 region cannot be excluded.

Downregulation of Kir6.1/SUR2B channels in the obese rat aorta.

OBJECTIVE: This study was designed to evaluate the contribution of adenosine triphosphate-dependent potassium channels to the increase in blood pressure observed in obese rats. METHODS: The experiment was performed in male Sprague-Dawley rats. Glibenclamide-sensitive currents were measured in vascular smooth muscle cells by patch-clamp. Expressions of Kir6.1 and SUR2B were examined by reverse transcription polymerase chain reaction and western blot techniques, respectively. RESULTS: In the aortic vascular smooth muscle cells, pinacidil induced glibenclamide-sensitive currents. The current from obese rats was significantly lower (-10.55 +/- 1.63 pA/pF) compared with that from the control rats (-20.18 +/- 2.79 pA/pF). Expressions of Kir6.1 and SUR2B were downregulated in vascular smooth muscle cells of aortas from the obese rats. CONCLUSION: These findings suggest that the adenosine triphosphate-dependent potassium channel is downregulated in smooth muscle cells from the aortas of obese rats, which may contribute to the increase in blood pressure in these rats.

[Association of variants in the vascular endothelial growth factor receptor 2 gene and the risk of hemorrhagic stroke].

OBJECTIVE: To assess whether variants in the vascular endothelial growth actor receptor 2 (VEGFR-2) gene confer susceptibility to stroke risk. METHODS: Association between gene variant rs2305948 (Val297Ile) and the risk of stroke was investigated in a multi-center case-control study, which comprised of 1849 patients with stroke (812 cerebral atherothrombosis, 530 lacunar infarction, and 507 intracerebral hemorrhage) and 1798 controls, and then replicated in the second independent stroke study (327 cases and 327 controls). The effect of Val297Ile on the binding ability of VEGFR-2 to VEGF was determined by a radioligand binding assay. RESULTS: The frequencies of carriers with variant 297Ile were significantly higher in patients with hemorrhagic stroke than in controls [297Val/Ile: 155(30.6%) versus 351 (19.5%), 297Ile/Ile: 18 (3.2%) versus 16 (1.0%); P < 0.01]. The variant 297Ile was significantly associated with increased risk of hemorrhagic stroke (odds ratio 2.25, 95% confidence interval 1.70-2.96; P < 0.01), and replication in the second stroke study obtained similar results. The substitution of Val to Ile at the amino acid residue 297 led to an increased equilibrium dissolved constant between VEGF and its receptor VEGFR-2 [297Val (87 +/- 9) pmol/L versus 297Ile (195 +/- 36) pmol/L, P < 0.01]. CONCLUSIONS: The VEGFR-2 gene variants may serve as novel genetic markers for the risk of hemorrhagic stroke.

[Study of inducing differentiation of bone marrow mesenchymal stem cells of rat into cardiac myocytes in vitro].

OBJECTIVE: To investigate the role of cardiac myocytes in the differentiation of bone marrow mesenchymal stem cells (MSCs) to cardiac myocytes and the biological properties in the course. METHODS: The bone marrow of the extremities of the rats was flushed, and bone marrow MSCs were obtained by method of density gradient centrifugation. They were cultured. The second passage of cultured MSCs were labelled with bromodeoxyuridine (BrdU). The cardiac myocytes were obtained from the apex of rat heart with trypsin digestion method, and they were cocultured with labeled MSCs. The developmental changes of bone marrow MSCs were observed under light microscope with immunohistochemical staining for BrdU and alpha-sarcomeric actin on the 3rd day, and electron microscopic examination on the 5th day. RESULTS: MSCs proliferated fast in primary culture and subculture, positive rate was (90.34+/-2.31)%, and there was statistical difference when it compared with control group [(4.07+/-1.35)%, P<0.01]. The morphology of MSCs changed significantly after coculture. There were new cells nuclei of which were positively stained for BrdU and its cytoplasm positive for actin. Under transmissive electron microscope, sarcomeres like structure and abnormal Z line were observed in cytoplasm. CONCLUSION: Cardiac myocytes can effectively induce bone marrow MSCs to differentiate into cardiac myocytes by coculturing.

[Sinoatrial node cells phenotype expression is induced by direct bone marrow stem cells contact with sinoatrial node cells].

OBJECTIVE: To observe the differentiation of bone mesenchymal stem cells (BMSCs) co-cultured with purified sinoatrial node cells (SNC) of neonate rats. METHODS: SNC from neonatal SD rat were cultured and purified with differential attachment method and labeled with BrdU. Rat BMSCs were isolated by a Percoll's gradient solution and cultured in DMEM. After 2 passages, these BMSCs were transfected with pEGFP-N1 by Lipofectamine and labeled with GFP. EGFP-BMSC were co-cultured with SNC in a rate of 1:5 for 1 week. EGFP-BMSC cultured in SNC culture medium served as controls. SNC marker hyperpolarization activated cyclic nucleotide gated cation channel 4 (HCN4) and connexin 45 (Cx45) expressions were determined by immunofluorescence staining. RESULT: Positive immunofluorescence staining against HCN4 and Cx45 were detected in EGFP-BMSC co-cultured with SNC but not in EGFP-BMSC cultured in SNC culture medium. CONCLUSION: Direct cell-to-cell contact between BMSCs and SNC cells may induce BMSCs differentiation into sinus node-like cells.

Altered ATP-sensitive potassium channels may underscore obesity-triggered increase in blood pressure.

AIM: To determine whether ATP-sensitive potassium channels are altered in VSMC from arotas and mesenteric arteries of obese rat, and their association with obesity-triggered increase in blood pressure. METHODS: Obesity was induced by 24 weeks of high-fat diet feeding in male Sprague-Dawley rats. Control rats were fed with standard laboratory rat chow. Blood pressure and body weight of these rats were measured every 4 weeks. At the end of 24 weeks, K(ATP) channelmediated relaxation responses in the aortas and mesenteric arteries, K(ATP) channel current, and gene expression were examined, respectively. RESULTS: Blood pressure and body weight were increased in rats fed with high-fat diet. K(ATP) channelmediated relaxation responses, currents, and K(ATP) expression in VSMC of both aortas and mesenteric arteries were inhibited in these rats. CONCLUSION: Altered ATP-sensitive potassium channels in obese rats may underscore obesity-triggered increase in blood pressure.