Search Results (167)

Ant venoms are rich sources of bioactive molecules, including peptide toxins with potent and selective activity on ion channels, which makes them valuable for pharmacological research and therapeutic development. Voltage-dependent potassium (Kv) channels, critical for regulating cellular excitability or cell cycle progression control, are targeted by a diverse array of venom-derived peptides. This study focuses on MYRTX_A4-Tb11a, a peptide from Tetramorium bicarinatum venom, which was previously shown to have a strong paralytic effect on dipteran species without cytotoxicity on insect cells. In the present study, we show that Tb11a exhibited no or low cytotoxicity toward mammalian cells either, even at high concentrations, while electrophysiological studies revealed a blockade of hKv1.3 activity. Additionally, Ta11a, an analog of Tb11a from the ant Tetramorium africanum, demonstrated similar Kv1.3 inhibitory properties. Structural analysis supports that the peptide acts on Kv1.3 channels through the functional dyad Y21-K25 and that the disulfide bridge is essential for biological activity, as reduction seems to disrupt the peptide conformation and impair the dyad. These findings highlight the importance of three-dimensional structure in channel modulation and establish Tb11a and Ta11a as promising Kv1.3 inhibitors. Future research should investigate their selectivity across additional ion channels and employ structure-function studies to further enhance their pharmacological potential. Full article

Although Brassica rapa (B. rapa) is vital in agricultural production and vulnerable to the pathogen Plasmodiophora, the intracellular water–nutrient metabolism and immunoregulation of Plasmodiophora infection in B. rapa leaves remain unclear. This study aimed to analyze the responsive mechanisms of Plasmodiophora-infected B. rapa using rapid detection technology. Six soil groups planted with Yangtze No. 5 B. rapa were inoculated with varying Plasmodiophora concentrations (from 0 to 10 × 10⁹ spores/mL). The results showed that at the highest infection concentration (PWB5, 10 × 10⁹ spores/mL) of B. rapa leaves, the plant electrophysiological parameters showed the intracellular water-holding capacity (IWHC), the intracellular water use efficiency (IWUE), and the intracellular water translocation rate (IWTR) declined by 41.99–68.86%. The unit for translocation of nutrients (UNF) increased by 52.83%, whereas the nutrient translocation rate (NTR), the nutrient translocation capacity (NTC), the nutrient active translocation (NAT) value, and the nutrient active translocation capacity (NAC) decreased by 52.40–77.68%. The cellular energy metabolism decreased with worsening Plasmodiophora infection, in which the units for cellular energy metabolism (∆G_E) and cellular energy metabolism (∆G) of the leaves decreased by 44.21% and 78.14% in PWB5, respectively. Typically, based on distribution of B-type dielectric substance transfer percentage (BPn), we found PWB4 (8 × 10⁹ spores/mL) was the maximal immune response concentration, as evidenced by a maximal BPn_R (B-type dielectric substance transfer percentage based on resistance), with increasing lignin and cork deposition to enhance immunity, and a minimum BPn_Xc (B-type dielectric substance transfer percentage based on capacitive reactance), with a decreasing quantity of surface proteins in the B. rapa leaves. This study suggests plant electrophysiological parameters could characterize intracellular water–nutrient metabolism and immunoregulation of B. rapa leaves under various Plasmodiophora infection concentrations, offering a dynamic detection method for agricultural disease management. Full article

The amyloid-beta 1-42 (Aβ1-42) oligomers are the most cytotoxic species of the amyloid family and play a key role in the pathology of Alzheimer’s Disease (AD). They have been shown to damage cellular membranes, but the exact mechanism is complex and not well understood. Multiple routes of membrane damage have been proposed, including the formation of pores and ion channels. In this work, we study the membrane damage induced by Aβ1-42 oligomers using black lipid membrane (BLM) electrophysiology and compare their action with gramicidin, known to form ion channels. Our data show that Aβ1-42 oligomers can induce a variety of damage in the lipid membranes composed of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), and cholesterol (CHOL), including small ion channels, similar to the gramicidin channels, with an average inner diameter smaller than 5 Å. These channels have a short retaining time in lipid membranes, suggesting that they are highly dynamic. Our studies provide new insights into the mechanism of membrane damage caused by Aβ1-42 oligomers and extend the current perception of the Aβ channelopathy hypothesis. It provides a more in-depth understanding of the molecular mechanism by which small Aβ oligomers induce cytotoxicity by interacting with lipid membranes in AD. Full article

Background: Human induced pluripotent stem cell cardiomyocytes (hiPSC-CMs) allow for high-throughput evaluation of cardiomyocyte (CM) physiology in health and disease. While multimodality testing provides a large breadth of information related to electrophysiology, contractility, and intracellular signaling in small populations of iPSC-CMs, current technologies for analyzing these parameters are expensive and resource-intensive. Methods: We have designed a novel 2D/3D hybrid organoid system that can harness optical imaging techniques to assess electromechanical properties and calcium dynamics across CMs in a high-throughput manner. We validated our methods using a doxorubicin-based system, as the drug has well-characterized cardiotoxic, pro-arrhythmic effects. Results: This novel hybrid system provides the functional benefit of 3D organoids while minimizing optical interference from multilayered cellular systems through our cell-culture techniques that propagate organoids outwards into 2D iPSC-CM sheets. The organoids recapitulate contractile forces that are more robust in 3D structures and connectivity, while 2D CMs facilitate analysis at an individual cellular level, which recreated numerous doxorubicin-induced electrophysiologic and propagation abnormalities. Conclusions: Thus, we have developed a novel 2D/3D hybrid organoid model that employs an integrated optical analysis platform to provide a reliable high-throughput method for studying cardiotoxicity, providing valuable data on calcium, contractility, and signal propagation. Full article

Both biochemical cues and the electrophysiological microenvironment play a pivotal role in influencing cell behaviors. In this study, collagen/polypyrrole biomimetic electroactive composite coatings with a fiber network structure were constructed on the surface of titanium substrates by hot alkali treatment and stepwise electrochemical deposition. Materialistic characterization and electrochemical performance tests demonstrated that the titanium electrodes modified with collagen/polypyrrole composite coatings exhibited the surface morphology of a collagen film layer, and their electroactivity was significantly enhanced. Cellular experiments demonstrated that the collagen in the composite coatings could provide good biomimetic biochemical cues as a main extracellular matrix component, which have a substantial effect in promoting cell adhesion, proliferation, and osteogenic differentiation. Furthermore, under exogenous electrical signals, the polypyrrole coating has the capacity to facilitate an appropriate electrophysiological microenvironment, thereby promoting osteogenic differentiation. The collagen/polypyrrole composite coating exhibited a better effect in promoting osteogenic differentiation among all samples by simultaneously providing the appropriate biochemical cues and electrophysiological microenvironments. This work demonstrates the feasibility of synergistic pro-osteogenesis by biochemical cues and an electrophysiological microenvironment, which is instructive for the field of bone tissue engineering. Full article

Cardiac arrhythmias, including atrial fibrillation and ventricular arrhythmias, remain leading causes of morbidity and mortality worldwide. While structural, electrical, and metabolic remodeling have long been recognized as drivers of arrhythmogenesis, emerging evidence identifies inflammation—particularly inflammasome signaling—as a central orchestrator of this pathological triad. Among the various inflammasome complexes, the NLRP3 inflammasome has garnered particular attention due to its activation in cardiomyocytes, fibroblasts, and immune cells in diverse clinical contexts. NLRP3 activation precipitates a cascade of downstream events, including interleukin-1β and -18 maturation, oxidative stress amplification, calcium mishandling, and extracellular matrix remodeling, thereby fostering a proarrhythmic substrate. This review synthesizes mechanistic and translational data implicating inflammasome signaling in both atrial and ventricular arrhythmias, with a focus on cellular specificity and electrophysiological sequelae. We explore upstream triggers, such as metabolic stress, gut dysbiosis, and epicardial adipose inflammation, and delineate the downstream impact on cardiac conduction and structural integrity. Emerging therapeutic strategies—including NLRP3 inhibitors, IL-1 antagonists, colchicine, and SGLT2 inhibitors—are critically appraised for their anti-inflammatory and antifibrotic potential. By bridging molecular insights with clinical application, this review underscores the inflammasome as a unifying mechanistic hub in arrhythmia pathogenesis and a promising target for precision-guided therapy. Full article

SH-SY5Y neuroblastoma cells can be effectively differentiated into a neuronal phenotype using retinoic acid (RA) and brain-derived neurotrophic factor (BDNF), making them a valuable in vitro model for studying neuronal differentiation. This study aimed to investigate the electrophysiological properties of SH-SY5Y cells following prolonged differentiation, with a focus on membrane characteristics, evoked action potentials, and the functionality of cellular components such as N-methyl-D-aspartate (NMDA) receptor. Whole-cell patch-clamp recordings were employed to evaluate ionic currents and action potentials in embryonic mouse cortical neurons (mCNs) and in both differentiated and undifferentiated SH-SY5Y neuroblastoma cells. Differentiated SH-SY5Y cells exhibited neurite outgrowth, evoked action potential firing, and functional NMDA receptor-mediated currents. Notably, atorvastatin significantly modulated the duration and firing of action potentials as well as NMDA receptor-mediated currents in differentiated SH-SY5Y cells. These findings highlight that neuronally differentiated SH-SY5Y cells expressing functional NMDA receptor-mediated currents serve as a robust and convenient model for investigating the molecular mechanisms of NMDA receptor function and for screening pharmacological agents targeting these receptors. Full article

Electrode designs and materials have become an increasingly important performance driver for microelectrode arrays, which are among the essential tools for cellular electrophysiology. Ongoing works have continuously innovated over a diverse range of electrode shapes, sizes, and materials. The large design and fabrication parameter space represents rich opportunities for optimizing performance and functionalities as well as a challenge for electrode developers due to a lack of predictive simulation software to aid design works. Electrode prototypes often need to be fabricated, empirically evaluated, and iteratively optimized at significant cost. Efficient hardware testing solutions to aid the development of new electrodes, especially at an early stage when the number of candidate designs is still high, are therefore increasingly important. Here, we propose and implement a cost-effective testbed platform, which is aimed at obtaining first-order characteristics from electrode prototypes to inform early-stage screening and refinement. Upon testing with microfabricated electrodes, the platform was shown to achieve an impedance measurement accuracy comparable to commercial equipment and effectively recorded extracellular action potentials of in vitro rat cortical neurons. By providing relevant electrode testing at a significantly lower cost, in a more compact form, and with greater ease of assembly, compared to existing hardware solutions, the presented testbed can meaningfully lower entry barriers for the development of new array-based electrophysiological microelectrodes. Full article

Pituitary cells are specialized cells located within the pituitary gland, a small, pea-sized gland situated at the base of the brain. Through the use of cellular electrophysiological techniques, the electrical properties of these cells have been revealed. This review paper aims to introduce the ion currents that are known to be functionally expressed in pituitary cells. These currents include a voltage-gated Na⁺ current (I_Na), erg-mediated K⁺ current (I_K(erg)), M-type K⁺ current (I_K(M)), hyperpolarization-activated cation current (I_h), and large-conductance Ca²⁺-activated K⁺ (BK_Ca) channel. The biophysical characteristics of the respective ion current were described. Additionally, we also provide explanations for the effect of various drugs or compounds on each of these currents. GH₃-cell exposure to GV-58 can increase the magnitude of I_Na with a concurrent rise in the inactivation time constant of the current. The presence of esaxerenone, an antagonist of the aldosterone receptor, directly suppresses the magnitude of peak and late I_Na. Risperidone, an atypical antipsychotic agent, is effective at suppressing the I_K(erg) amplitude directly, and di(2-ethylhexyl)-phthalate suppressed I_K(erg). Solifenacin and kynurenic acid can interact with the K_M channel to stimulate I_K(M), while carisbamate and cannabidiol inhibit the I_h amplitude activated by sustained hyperpolarization. Moreover, the presence of either rufinamide or QO-40 can enhance the activity of single BK_Ca channels. To summarize, alterations in ion currents within native pituitary cells or pituitary tumor cells can influence their functional activity, particularly in processes like stimulus–secretion coupling. The effects of small-molecule modulators, as demonstrated here, bear significance in clinical, therapeutic, and toxicological contexts. Full article

Voltage-gated Ca²⁺ (Ca_V) channels are transmembrane proteins comprising the pore-forming subunit Ca_Vα₁ and the ancillary proteins Ca_Vα₂δ and Ca_Vβ. They are expressed in various tissues, including the nervous system, where they regulate Ca²⁺ entry in response to membrane potential changes. The increase in intracellular Ca²⁺ allows for regulating cell excitability and releasing neurotransmitters, among other cellular events. Leucine-rich repeat kinase 2 (LRRK2) is a serine–threonine kinase involved in vesicular mobilization. Previously, it has been shown that LRRK2 regulates neurotransmission by phosphorylating the Ca_Vβ auxiliary subunit of the Ca_V2.1 (P/Q-type) presynaptic channels. However, it is unknown whether the kinase can regulate the activity of other Ca_V channel subtypes, such as Ca_V1.3 (L-type), which play a significant role in the excitability of dopaminergic neurons in the substantia nigra pars compacta (SNc) and whose dysregulation contributes to neurodegeneration in Parkinson’s disease (PD). Here, we found potential phosphorylation sites for LRRK2 in Ca_Vβ₃ and examined how these molecules interact. We used immunoprecipitation and electrophysiology in HEK-293 cells expressing recombinant Ca_V1.3 channels, both with and without wild-type LRRK2 or its LRRK2^G2019S mutation, which plays a role in familial PD through a possible gain-of-toxic-function mechanism. Our results show that LRRK2^G2019S significantly increases current density through Ca_V1.3 channels, and this effect depends on the presence of Ca_Vβ₃. Site-directed mutagenesis revealed that phosphorylation at S152 in the sequence of Ca_Vβ₃ is necessary and sufficient to explain the abnormal regulation of the channels mediated by LRRK2^G2019S. These data provide new insights into the molecular regulation that mutant LRRK2 may exert on L-type Ca_V1.3 channels, which determine pacemaker activity in dopaminergic neurons of the SNc and may, therefore, play a relevant role in the molecular pathophysiology of PD. Full article

Mangroves are landscape plants in coastal parks and are also typical salt-tolerant plants. Water–salt transport plays a key role in their adaptations to salinity. This research aims to study the synchronous dynamics of intracellular water–salt and plant adaptation mechanisms. Therefore, no salt and three salinity gradients, including 0.1, 0.2, and 0.4 mol/L NaCl, were applied to three mangrove plants. An electrophysiological sensor was used to non-invasively detect plant electrical signals. The results showed that mangroves’ water and salt dynamic characteristics differed under salt treatment. Rhizophora stylosa reduced the cytoplasmic salt by increasing water absorption, enhancing salt exclusion, and decreasing salt inflow. Kandelia candel managed salt by transferring it into a vacuole, diluting the intracellular salt concentrations through increased cell fluid while maintaining the salt exclusion capacity as salinity increased. Aegiceras corniculatum decreased the cellular salt influx and adapted to 0.4 mol/L NaCl by activating salt secretion. In addition, water-use, salt transport, cellular endogenous convertible energy, and photosynthetic gas exchange parameters could be used as representative factors for salt adaptation of these mangrove species. The results deepen our understanding of plant salt tolerance mechanisms and provide a new approach for timely determining plant adaptability. Full article

Sudden cardiac death (SCD), the most devastating complication of hypertrophic cardiomyopathy (HCM), is primarily triggered by ventricular tachycardia or fibrillation. Despite advances in knowledge, the mechanisms driving ventricular arrhythmia in HCM remain incompletely understood, stemming from an interplay of multiple pro-arrhythmic factors. Myocyte disarray and myocardial fibrosis form a structural substrate favorable to re-entrant arrhythmias by altering myocardial electrophysiological properties, while cellular abnormalities predominate in patients without evident structural remodeling. Traditional SCD risk prediction models rely on clinical risk factors and regression-based risk estimation, often overlooking specific arrhythmic substrates. Emerging techniques now allow for the direct assessment of these substrates, providing deeper insights into the arrhythmogenic mechanisms and paving the way for more personalized SCD risk stratification. This review explores the contribution of cellular, structural, and electrophysiological substrates to arrhythmic risk in HCM, emphasizing their distinct roles. Furthermore, it highlights the potential of substrate-based approaches to refining SCD prevention strategies and improving outcomes for patients with HCM. Full article

Genetically encoded voltage indicators (GEVIs) allow for the cell-type-specific real-time imaging of neuronal membrane potential dynamics, which is essential to understanding neuronal information processing at both cellular and circuit levels. Among GEVIs, near-infrared-shifted GEVIs offer faster kinetics, better tissue penetration, and compatibility with optogenetic tools, enabling all-optical electrophysiology in complex biological contexts. In our previous work, we employed the directed molecular evolution of microbial rhodopsin Archaerhodopsin-3 (Arch-3) in mammalian cells to develop a voltage sensor called Archon1. Archon1 demonstrated excellent membrane localization, signal-to-noise ratio (SNR), sensitivity, kinetics, and photostability, and full compatibility with optogenetic tools. However, Archon1 suffers from low brightness and requires high illumination intensities, which leads to tissue heating and phototoxicity during prolonged imaging. In this study, we aim to improve the brightness of this voltage sensor. We performed random mutation on a bright Archon derivative and identified a novel variant, monArch, which exhibits satisfactory voltage sensitivity (4~5% ΔF/F_AP) and a 9-fold increase in basal brightness compared with Archon1. However, it is hindered by suboptimal membrane localization and compromised voltage sensitivity. These challenges underscore the need for continued optimization to achieve an optimal balance of brightness, stability, and functionality in rhodopsin-based voltage sensors. Full article

How can cellular electrophysiology measurements and mathematical modeling of ionic channels help to identify pivotal targets in disease-related cell signaling? The purpose of this review is to highlight the advantages and disadvantages of using both of these complementary techniques to determine molecular targets that may be structurally or functionally altered in a specific disease. In addition, both electrophysiology measurements and mathematical modeling may improve coordinated drug development, accelerate the prediction of new drugs, and facilitate repositioning of pharmacological agents. This review focuses on the data obtained from electrophysiology and mathematical model approaches, including intracellular recording, cellular patch clamp measurements, and the Hodgkin and Huxley equation, as key precision methodologies. To this end, seminiferous tubules, the Sertoli cell line (TM4), and/or primary cultures of Sertoli cells were used to explore the role of follicle-stimulating hormone (FSH), thyroid hormones, retinol, testosterone, and 1,25(OH)₂ vitamin D₃ in the coordinated activation or inhibition of ionic channels essential for male fertility. Based on the discussed data, Sertoli cells precisely regulate their biological activity by coordinating channel activity according to the hormonal environment and the nutritional requirements required for germ cell development. Full article

Somatic mutations are common in cancer, with only a few driving the progression of the disease, while most are silent passengers. Some mutations may hinder or even reverse cancer progression. The voltage-gated proton channel (H_V1) plays a key role in cellular pH homeostasis and shows increased expression in several malignancies. Inhibiting H_V1 in cancer cells reduces invasion, migration, proton extrusion, and pH recovery, impacting tumor progression. Focusing on HVCN1, the gene coding for the human voltage-gated proton channel (hH_V1), 197 mutations were identified from three databases: 134 missense mutations, 51 sense mutations, and 12 introducing stop codons. These mutations cluster in two hotspots: the central region of the N-terminus and the region coding for the S4 transmembrane domain, which contains the channel’s voltage sensor. Five somatic mutations within the S4 segment (R205W, R208W, R208Q, G215E, and G215R) were selected for electrophysiological analysis and MD simulations. The findings reveal that while all mutants remain proton-selective, they all exhibit reduced effective charge displacement and proton conduction. The mutations differentially affect hH_V1 kinetics, with the most pronounced effects observed in the two Arg-to-Trp substitutions. Mutation of the first voltage-sensing arginine (R1) to tryptophan (R205W) causes proton leakage in the closed state, accelerates channel activation, and diminishes the voltage dependence of gating. Except for R205W, the mutations promote the deactivated channel configuration. Altogether, these data are consistent with impairment of hH_V1 function by mutations in the S4 transmembrane segment, potentially affecting pH homeostasis of tumor cells. Full article