scholarly journals Three-Week-Old Rabbit Ventricular Cardiomyocytes as a Novel System to Study Cardiac Excitation and EC Coupling

2021 ◽  
Vol 12 ◽  
Author(s):  
Anatoli Y. Kabakov ◽  
Elif Sengun ◽  
Yichun Lu ◽  
Karim Roder ◽  
Peter Bronk ◽  
...  
Keyword(s):  
Potassium Current ◽  
Molecular Mechanisms ◽  
Low Cost ◽  
Inward Rectifier ◽  
Adult Rabbit ◽  
Voltage Gated ◽  
Channel Proteins ◽  
Ventricular Cardiomyocytes ◽  
Gated Channel ◽  
Cardiac Excitation

Cardiac arrhythmias significantly contribute to cardiovascular morbidity and mortality. The rabbit heart serves as an accepted model system for studying cardiac cell excitation and arrhythmogenicity. Accordingly, primary cultures of adult rabbit ventricular cardiomyocytes serve as a preferable model to study molecular mechanisms of human cardiac excitation. However, the use of adult rabbit cardiomyocytes is often regarded as excessively costly. Therefore, we developed and characterized a novel low-cost rabbit cardiomyocyte model, namely, 3-week-old ventricular cardiomyocytes (3wRbCMs). Ventricular myocytes were isolated from whole ventricles of 3-week-old New Zealand White rabbits of both sexes by standard enzymatic techniques. Using wheat germ agglutinin, we found a clear T-tubule structure in acutely isolated 3wRbCMs. Cells were adenovirally infected (multiplicity of infection of 10) to express Green Fluorescent Protein (GFP) and cultured for 48 h. The cells showed action potential duration (APD90 = 253 ± 24 ms) and calcium transients similar to adult rabbit cardiomyocytes. Freshly isolated and 48-h-old-cultured cells expressed critical ion channel proteins: calcium voltage-gated channel subunit alpha1 C (Cavα1c), sodium voltage-gated channel alpha subunit 5 (Nav1.5), potassium voltage-gated channel subfamily D member 3 (Kv4.3), and subfamily A member 4 (Kv1.4), and also subfamily H member 2 (RERG. Kv11.1), KvLQT1 (K7.1) protein and inward-rectifier potassium channel (Kir2.1). The cells displayed an appropriate electrophysiological phenotype, including fast sodium current (INa), transient outward potassium current (Ito), L-type calcium channel peak current (ICa,L), rapid and slow components of the delayed rectifier potassium current (IKr and IKs), and inward rectifier (IK1). Although expression of the channel proteins and some currents decreased during the 48 h of culturing, we conclude that 3wRbCMs are a new, low-cost alternative to the adult-rabbit-cardiomyocytes system, which allows the investigation of molecular mechanisms of cardiac excitation on morphological, biochemical, genetic, physiological, and biophysical levels.

scholarly journals Decreased inward rectifier potassium current IK1in dystrophin-deficient ventricular cardiomyocytes

Channels ◽  
2016 ◽  
Vol 11 (2) ◽  
pp. 101-108 ◽  
Author(s):  
Lena Rubi ◽  
Xaver Koenig ◽  
Helmut Kubista ◽  
Hannes Todt ◽  
Karlheinz Hilber
Keyword(s):  
Potassium Current ◽  
Inward Rectifier ◽  
Ventricular Cardiomyocytes ◽  
Inward Rectifier Potassium Current

Role of Phytochemicals in the Treatment of Breast Cancer: Natural Swords battling Cancer Cells

2021 ◽  
Vol 16 ◽  
Author(s):  
Rajni Sawanny ◽  
Sheersha Pramanik ◽  
Unnati Agarwal
Keyword(s):  
Breast Cancer ◽  
Molecular Mechanisms ◽  
Low Cost ◽  
Epigallocatechin Gallate ◽  
Cancer Therapeutics ◽  
Treatment Modalities ◽  
Breast Cancer Patients ◽  
Scientific Validity ◽  
Phytochemical Study ◽  
Treat Breast Cancer

: Breast cancer is the most common type of malignancy among ladies (around 30% of newly diagnosed patients every year). To date, various modern treatment modalities for breast cancer, such as radiotherapy, surgical method, hormonal therapy, and chemotherapeutic drug utilisation, are available. However, adverse drug reactions, therapeutic resistance, metastasis, or cancer reoccurrence chances remain the primary causes of mortality for breast cancer patients. To overcome all the potential drawbacks, we need to investigate novel techniques and strategies previously not considered and treat breast cancer effectively with safety and efficacy. For centuries, we utilise phytochemicals to treat various diseases because of their safety, low-cost & least or no side effects. Recently, naturally produced phytochemicals gain immense attention as potential breast cancer therapeutics because of their ideal characteristics; for instance, they operate via modulating molecular pathways associated with cancer growth and progression. The primary mechanism involves inhibition of cell proliferation, angiogenesis, migration, invasion, increasing anti-oxidant status, initiation of the arrest of the cell cycle, and apoptosis. Remedial viability gets effectively enhanced when phytochemicals work as adjuvants with chemotherapeutic drugs. This comprehensive review revolves around the latest chemopreventive, chemotherapeutic, and chemoprotective treatments with their molecular mechanisms to treat breast cancer by utilising phytochemicals such as vinca alkaloids, resveratrol, curcumin, paclitaxel, silibinin, quercetin, genistein and epigallocatechin gallate. The authors wish to extend the field of phytochemical study for its scientific validity and its druggability.

scholarly journals Proanthocyanidins against Oxidative Stress: From Molecular Mechanisms to Clinical Applications

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Lingyu Yang ◽  
Dehai Xian ◽  
Xia Xiong ◽  
Rui Lai ◽  
Jing Song ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Signaling Pathways ◽  
Molecular Mechanisms ◽  
Metabolic Diseases ◽  
Low Cost ◽  
Natural Agents ◽  
Molecular Damage ◽  
And Control

Proanthocyanidins (PCs) are naturally occurring polyphenolic compounds abundant in many vegetables, plant skins (rind/bark), seeds, flowers, fruits, and nuts. Numerousin vitroandin vivostudies have demonstrated myriad effects potentially beneficial to human health, such as antioxidation, anti-inflammation, immunomodulation, DNA repair, and antitumor activity. Accumulation of prooxidants such as reactive oxygen species (ROS) exceeding cellular antioxidant capacity results in oxidative stress (OS), which can damage macromolecules (DNA, lipids, and proteins), organelles (membranes and mitochondria), and whole tissues. OS is implicated in the pathogenesis and exacerbation of many cardiovascular, neurodegenerative, dermatological, and metabolic diseases, both through direct molecular damage and secondary activation of stress-associated signaling pathways. PCs are promising natural agents to safely prevent acute damage and control chronic diseases at relatively low cost. In this review, we summarize the molecules and signaling pathways involved in OS and the corresponding therapeutic mechanisms of PCs.

Inhibition of transient potassium current in cultured and acutely dissociated mouse hippocampal neurons by GABAA receptor activation

1996 ◽  
Vol 76 (2) ◽  
pp. 816-824
Author(s):  
R. L. Wu ◽  
M. E. Barish
Keyword(s):  
Mouse Brain ◽  
Hippocampal Neurons ◽  
Potassium Current ◽  
Receptor Activation ◽  
Gabab Receptors ◽  
Cell Swelling ◽  
Cultured Neurons ◽  
Embryonic Mouse ◽  
Voltage Gated ◽  
A Current

1. The regulation of A-current, one of several transient voltage-gated potassium currents, was studied using whole cell gigaohm seal voltage-clamp techniques on hippocampal pyramidal neurons that were either acutely dissociated from postnatal mouse brain or isolated from embryonic mouse brain and grown in dissociated culture. These neurons also express gamma-aminobutyric acid-A (GABAA) receptors, the activation of which can, under some circumstances, depolarize immature neurons and the dendrites of more mature neurons. 2. Application of GABA (50 microM) reduced the amplitude of A-current when potassium current amplitude was measured during a period of slow and incomplete desensitization of IGABA. A-current was reduced to 67 +/- 9% of control (mean +/- SD, n - 14) in acutely dissociated neurons, and to 64 +/- 11% of control (n = 15) in cultured neurons. Similar A-current reductions were seen in large outside-out membrane patches pulled from somata of cultured neurons, an observation suggesting that imperfect control of membrane voltage was not responsible for A-current inhibition. 3. A-current inhibition exhibited the sensitivity expected of a GABAA-sensitive process. It was mimicked by muscimol and blocked by bicuculline, picrotoxin, and reduction of [Cl-] in the external solution. Baclophen and phaclophen, effective as agonist and antagonist on GABAB receptors, did not affect A-currents or their inhibition. Reduction in extracellular osmolarity (to increase cell swelling as might occur with Cl- entry), or removal of external HCO3- (which might flow inward through GABAA channels and cause local external acidification), did not affect A-current or its inhibition. The mechanisms of inhibition is not clear at present. 4. We suggest that reduced A-current may favor GABA-induced depolarization and consequent activation of voltage-gated calcium channels.

Differential distribution of Kir2.1 and Kir2.3 subunits in canine atrium and ventricle

2002 ◽  
Vol 283 (3) ◽  
pp. H1123-H1133 ◽  
Author(s):  
Peter Melnyk ◽  
Liming Zhang ◽  
Alvin Shrier ◽  
Stanley Nattel
Keyword(s):  
Molecular Mechanisms ◽  
Inward Rectifier ◽  
Differential Distribution ◽  
Atrial Cells ◽  
Ventricular Cells ◽  
Subunit Expression ◽  
Intercalated Disks ◽  
Protein Density ◽  
Cell Data ◽  
Isolated Cell

Ventricular inward rectifier K+ current ( I K1) is substantially larger than atrial, producing functionally important action potential differences. To evaluate possible molecular mechanisms, we recorded I K1 with patch-clamp techniques and studied Kir2.1 and Kir2.3 subunit expression. I K1density was >10-fold larger in the canine ventricle than atrium. Kir2.1 protein expression (Western blot) was 78% greater ( P < 0.01) in the ventricle, but Kir2.3 band density was 228% greater ( P < 0.01) in the atrium. Immunocytochemistry showed transverse tubular localization of Kir2.1 in 89% (17 of 19) of ventricular and 26% (5 of 19, P < 0.0001) of atrial cells. Both exhibited a weakly positive Kir2.1 signal at intercalated disks. Kir2.3 was strongly expressed at the intercalated disks in all cells and in the transverse tubular regions in 78% (14 of 18) of atrial and 22% (4 of 18, P < 0.001) of ventricular cells. Tissue immunohistochemical results qualitatively resembled isolated cell data. We conclude that the expression density and subcellular localization of Kir2.1 and Kir2.3 subunits differ in the canine atrium versus ventricle. Overall protein density differences are insufficient to explain I K1 discrepancies, which may be related to differences in subcellular distribution.

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