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Ventricular Cardiomyocytes (ventricular + cardiomyocyte)
Selected AbstractsMolecular characterization of regenerated cardiomyocytes derived from adult mesenchymal stem cellsCONGENITAL ANOMALIES, Issue 1 2002Keiichi Fukuda ABSTRACT, We recently isolated a cardiomyogenic (CMG) cell line from murine bone marrow stroma, and in this paper characterize regenerated cardiomyocytes derived from adult mesenchymal stem cells at the molecular level. Stromal cells were immortalized, exposed to 5-azacytidine, and repeatedly screened for spontaneously beating cells. CMG cells began to beat spontaneously after 2 weeks, and beat synchronously after 3 weeks. They exhibited sinus-node-like or ventricular-cell-like action potentials. Analysis of the isoforms of contractile protein genes, such as of myosin and ,-actin, indicated that their phenotype was similar to that of fetal ventricular cardiomyocytes. The cells expressed Nkx2.5, GATA4, TEF-1, and MEF2-C mRNA before 5-azacytidine exposure, and MEF2-A and MEF2-D after exposure. CMG cells expressed ,1A, ,1B, and ,1D -adrenergic receptor mRNA prior to differentiation, and ,1, ,2 -adrenergic and M1, M2 -muscarinic receptors after acquiring the cardiomyocyte phenotype. Phenylephrine induced phosphorylation of ERK1/ 2, and the phosphorylation was inhibited by prazosin. Isoproterenol increased the cAMP level 38-fold and beating rate, cell motion, % shortening, and contractile velocity by 48%, 38%, 27%, and 51%, respectively, and the increases were blocked by CGP20712A (,1 -selective blocker). Car-bachol increased IP3 32-fold, and the increase was inhibited by AFDX116 (M2 -selective blocker). These findings demonstrated that the regenerated cardiomyocytes were capable of responding to adrenergic and muscarinic stimulation. This new cell line provides a model for the study of cardiomyocyte transplantation. [source] Melatonin and its analogs potentiate the nifedipine-sensitive high-voltage-activated calcium current in the chick embryonic heart cellsJOURNAL OF PINEAL RESEARCH, Issue 1 2001Y.A. Mei Effects of melatonin and its analogs on the voltage-activated calcium current of embryonic chick ventricular cardiomyocytes were investigated. Myocytes were dissociated from 14- to 16-day-old chicks (yellow Red Rob) embryonic hearts and cultured for 2,3 days. Calcium currents were studied by the patch-clamp technique. Whole-cell current recording showed nifedipine-sensitive, high-voltage-activated L-type calcium current inactivated in 70,100 ms during the voltage step period of 200 ms. There was no evidence of low-voltage-activated T-type calcium channels. Melatonin (ejected solution: 50 ,mol/L melatonin; concentration at the vicinity of recording cell: about 1,5 ,mol/L melatonin) and its analogs, 2-iodomelatonin and 2-iodo-n-butanol-5-methoxytryptamine, significantly increased the amplitude of the calcium current by 42,62%. The effect of melatonin on the L-type calcium current was not desensitised by repeated melatonin treatment. Our results suggest a specific melatonin receptor-mediated action on the calcium channel of the embryonic chick myocyte. The melatonin-induced increase in high-voltage calcium current may increase myocyte contractility and enhance cardiac output. A regulatory role of melatonin on the chick cardiac function should be further considered. [source] Expression pattern of neuronal and skeletal muscle voltage-gated Na+ channels in the developing mouse heartTHE JOURNAL OF PHYSIOLOGY, Issue 3 2005Volker Haufe In the mammalian heart, a variety of voltage-gated Na+ channel transcripts and proteins have been detected. However, little quantitative information is available on the abundance of each transcript during development, or the contribution of TTX-sensitive Na+ channels to the cardiac sodium current (INa). Using competitive and real-time RT-PCR we investigated the transcription of six Na+ channels (Nav1.1,Nav1.6) and the ,1 subunit during mouse heart development. Nav1.5 was predominantly expressed in the adult heart, whereas the splice variant Nav1.5a was the major Na+ channel isoform in embryonic hearts. The TTX-resistant Na+ channel transcripts (Nav1.5 and Nav1.5a) increased 1.7-fold during postnatal development. Transcripts encoding TTX-sensitive Na+ channels (Nav1.1,Nav1.4) and the ,1 subunit gradually increased up to fourfold from postnatal day (P)1 to P126, while the Nav1.6 transcript level remained low and constant over the same period. In adults, TTX-sensitive channel mRNA accounted for 30,40% of the channel pool in whole-heart preparations (Nav1.3 > Nav1.4 > Nav1.2 , Nav1.1 , Nav1.6), and 16% in mRNA from isolated cardiomyocytes (Nav1.4 > Nav1.3 > Nav1.2 > Nav1.1 > Nav1.6). Confocal immunofluorescence on ventricular myocytes suggested that Nav1.1 and Nav1.2 were localized at the intercalated disks and in the t tubules. Nav1.3 labelling predominantly produced a diffuse but strong intracellular signal. Nav1.6 fluorescence was detected only along the Z lines. Electrophysiological recordings showed that TTX-sensitive and TTX-resistant Na+ channels, respectively, accounted for 8% and 92% of the INa in adult ventricular cardiomyocytes. Our data suggest that neuronal and skeletal muscle Na+ channels contribute to the action potential of cardiomyocytes in the adult mammalian heart. [source] NADH supplementation decreases pinacidil-primed IK(ATP) in ventricular cardiomyocytes by increasing intracellular ATPBRITISH JOURNAL OF PHARMACOLOGY, Issue 4 2003Brigitte Pelzmann The aim of this study was to investigate the effect of nicotinamide-adenine dinucleotide (NADH) supplementation on the metabolic condition of isolated guinea-pig ventricular cardiomyocytes. The pinacidil-primed ATP-dependent potassium current IK(ATP) was used as an indicator of subsarcolemmal ATP concentration and intracellular adenine nucleotide contents were measured. Membrane currents were studied using the patch-clamp technique in the whole-cell recording mode at 36,37°C. Adenine nucleotides were determined by HPLC. Under physiological conditions (4.3 mM ATP in the pipette solution, ATPi) IK(ATP) did not contribute to basal electrical activity. The ATP-dependent potassium (K(ATP)) channel opener pinacidil activated IK(ATP) dependent on [ATP]i showing a significantly more pronounced activation at lower (1 mM) [ATP]i. Supplementation of cardiomyocytes with 300 ,g ml,1 NADH (4,6 h) resulted in a significantly reduced IK(ATP) activation by pinacidil compared to control cells. The current density was 13.8±3.78 (n=6) versus 28.9±3.38 pA pF,1 (n=19; P<0.05). Equimolar amounts of the related compounds nicotinamide and NAD+ did not achieve a similar effect like NADH. Measurement of adenine nucleotides by HPLC revealed a significant increase in intracellular ATP (NADH supplementation: 45.6±1.88 nmol mg,1 protein versus control: 35.4±2.57 nmol mg,1 protein, P<0.000005). These data show that supplementation of guinea-pig ventricular cardiomyocytes with NADH results in a decreased activation of IK(ATP) by pinacidil compared to control myocytes, indicating a higher subsarcolemmal ATP concentration. Analysis of intracellular adenine nucleotides by HPLC confirmed the significant increase in ATP. British Journal of Pharmacology (2003) 139, 749,754. doi:10.1038/sj.bjp.0705300 [source] BMP-2 and FGF-2 Synergistically Facilitate Adoption of a Cardiac Phenotype in Somatic Bone Marrow c-kit+/Sca-1+ Stem CellsCLINICAL AND TRANSLATIONAL SCIENCE, Issue 2 2008Brent R. DeGeorge, Jr. B.S. Abstract The aim of this study was to explore the effect of bone morphogenetic protein-2 (BMP-2) and fibroblast growth factor-2 (FGF-2), paracrine factors implicated in both cardiac embryogenesis and cardiac repair following myocardial infarction (MI),on murine bone marrow stem cell (mBMSC) differentiation in an ex vivo cardiac microenvironment. For this purpose, green fluorescent protein (GFP) expressing hematopoietic lineage negative (lin-) c-kit ligand (c-kit) and stem cell antigen-1 (Sca-1) positive (GFP-lin-/c-kit+/sca+) mBMSC were co-cultured with neonatal rat ventricular cardiomyocytes (NVCMs). GFP+ mBMSC significantly induced the expression of BMP-2 and FGF-2 in NVCMs, and approximately 4% GFP+ mBMSCs could be recovered from the co-culture at day 10. The addition of BMP-2 in concert with FGF-2 significantly enhanced the amount of integrated GFP+ mBMSCs by 5-fold (,20%), whereas the addition of anti-BMP-2 and/or anti-FGF-2 antibodies completely abolished this effect. An analysis of calcium cycling revealed robust calcium transients in GFP+ mBMSCs treated with BMP-2/FGF-2 compared to untreated co-cultures. BMP-2 and FGF-2 addition led to a significant induction of early (NK2 transcription factor related, locus 5; Nkx2.5, GATA binding protein 4; GATA-4) and late (myosin light chain kinase [MLC-2v], connexin 43 [Cx43]) cardiac marker mRNA expression in mBMSCs following co-culture. In addition, re-cultured fluorescence-activated cell sorting (FACS)-purified BMP-2/FGF-2-treated mBMSCs revealed robust calcium transients in response to electrical field stimulation which were inhibited by the L-type calcium channel (LTCC) inhibitor, nifedipine, and displayed caffeine-sensitive intracellular calcium stores. In summary, our results show that mBMSCs can adopt a functional cardiac phenotype through treatment with factors essential to embryonic cardiogenesis that are induced after cardiac ischemia. This study provides the first evidence that mBMSCs with long-term self-renewal potential possess the capability to serve as a functional cardiomyocyte precursor through the appropriate paracrine input and cross-talk within an appropriate cardiac microenvironment. [source] | |||||||||||||