L-type Ca2 Research Articles

Effects of benidipine, paracetamol, and their combination on postoperative and normal tissue pain thresholds.

Introduction: In clinical practice, inadequate pain inhibition leads to increased morbidity and mortality. Increased intracellular calcium, oxidants, and proinflammatory cytokines are known to play a role in the pathogenesis of postoperative pain. Therefore, we investigated the analgesic effects of benidipine, paracetamol, and benidipine-paracetamol combination (BPC) on postoperative and normal pain thresholds in rats. Material and methods: Sixty-four male albino Wistar rats weighing 285-295g were used. The without-incision rats were divided into 4 subgroups: healthy control, benidipine alone, paracetamol alone, and BPC. The scalpel-incision rats were divided into 4 subgroups: scalpel incision, scalpel incision + benidipine, scalpel incision + paracetamol, and scalpel incision + BPC. Paw pain thresholds of rats were measured using a Basile algesimeter. Biochemical analyses were performed on the paw tissues of 6 rats randomly taken from the experimental groups, each containing 8 rats. Rats were sacrificed immediately after the measurements. After the pain threshold tests were finished, the paw tissues were removed and malondialdehyde (MDA), total glutathione (tGSH), cyclooxygenase (COX), and interleukin-6 (IL-6) levels were measured. Results: There was no significant difference between the groups in paw pain threshold and measured biochemical parameters in rats without incision. The decrease in the pain threshold of the incised paw was also best prevented by BPC, followed by benidipine and then paracetamol. Furthermore, increases in scalpel-incised paw tissue MDA, COX-2, and IL-6 levels and the decrease in tGSH were significantly suppressed by benidipine and BPC, while paracetamol could only significantly inhibit the increase in IL-6 production. Conclusion: The combination of the L-type Ca2+ channel blocker benidipine and paracetamol (BPC) may provide potent analgesia. Our experimental results support that BPC may be useful in the treatment of severe pain that cannot be adequately inhibited by paracetamol.

L-methionine and the L-type Ca2+ channel agonist BAY K 8644 collaboratively contribute to the reduction of depressive-like behavior in mice.

The L-type Ca2+ channel (LTCC, also known as Cav1,2) is involved in the regulation of key neuronal functions, such as dendritic information integration, cell survival, and neuronal gene expression. Clinical studies have shown an association between L-type calcium channels and the onset of depression, although the precise mechanisms remain unclear. The development of depression results from a combination of environmental and genetic factors. DNA methylation, a significant epigenetic modification, plays a regulatory role in the pathogenesis of psychiatric disorders such as posttraumatic stress disorder (PTSD), depression, and autism. In our study, we observed reduced Dnmt3a expression levels in the hippocampal DG region of mice with LPS-induced depression compared to control mice. The antidepressant Venlafaxine was able to increase Dnmt3a expression levels. Conversely, Bay K 8644, an agonist of the L-type Ca2+ channel, partially ameliorated depression-like behaviors but did not elevate Dnmt3a expression levels. Furthermore, when we manipulated DNA methylation levels during Bay K 8644 intervention in depression-like models, we found that enhancing the expression of Dnmt3a could improve LPS-induced depression/anxiety-like behaviors, while inhibiting DNA methylation exacerbated anxiety-like behaviors, the combined use of BAY K 8644 and L-methionine can better improve depressive-like behavior. These findings indicate that DNA methylation plays a role in the regulation of depression-like behaviors by the L-type Ca2+ channel, and further research is needed to elucidate the interactions between DNA methylation and L-type Ca2+ channels.

The calcium transient coupled to the L-type calcium current attenuates cardiac alternans.

Cardiac action potential (AP) alternans have been linked to the development of arrhythmia. AP alternans may be driven by AP instabilities, Ca2+ transient (CaT) instabilities, or both. The mechanisms underlying CaT driven AP alternans is well-supported experimentally, but the ionic mechanism underlying alternans driven by AP instabilities remain incompletely understood. Here we used the Ca2+ buffer BAPTA to remove the CaT and generate a model of AP alternans driven primarily by AP instabilities. In isolated rabbit ventricle myocytes, AP alternans induced by rapid pacing were either critically damped and persisted over time, overdamped and ceased over seconds, or underdamped progressing to 2:1 capture. Control cells predominantly exhibited critically damped alternans. In contrast, removing CaT with BAPTA destabilized alternans formation in a concentration dependent manner. Importantly, alternans were easier to induce in CaT free cells as evidenced by a higher alternans threshold relative to control cells. While the L-type Ca2+ channel agonist Bay K 8644 had a minor effect on alternans formation in myocytes with conserved CaT, combining the agonist with BAPTA markedly promoted the formation of underdamped alternans and increased the alternans threshold more than four-fold as compared to controls. Our data support a mechanistic model in which AP alternans are a primary self-sustained event in which the CaT serves as a dampening cue that curbs alternans development, likely via a canonical negative feedback process involving Ca2+ induced inhibition of L-type Ca2+ current.

The quercetin metabolite 4-methylcatechol causes vasodilation via voltage-gated potassium (KV) channels.

Dietary polyphenols have been associated with many beneficial cardiovascular effects. However, these effects are rather attributed to small phenolic metabolites formed by the gut microbiota, which reach sufficient concentrations in systemic circulation. 4-Methylcatechol (4-MC) is one such metabolite. As it is shown to possess considerable vasorelaxant effects, this study aimed to unravel its mechanism of action. To this end, experimental in vitro and in silico approaches were employed. In the first step, isometric tension recordings were performed on rat aortic rings. 4-MC potentiated the effect of cyclic nucleotides, but the effect was not mediated by either soluble guanylyl cyclase (sGC), modification of cyclic adenosine monophosphate levels, or protein kinase G. Hence, downstream targets such as calcium or potassium channels were considered. Inhibition of voltage-gated K+ channels (KV) markedly decreased the effect of 4-MC, and vasodilation was partly decreased by inhibition of the KV7 isoform. Contrarily, other types of K+ channels or L-type Ca2+ channels were not involved. In silico reverse docking confirmed that 4-MC binds to KV7.4 through hydrogen bonding and hydrophobic interactions. In particular, it interacts with two crucial residues for KV7.4 activation: Trp242 and Phe246. In summary, our findings suggested that 4-MC exerts vasorelaxation by opening KV channels with the involvement of KV7.4.

Panax notoginseng root extract induces nuclear translocation of CRTC1 and Bdnf mRNA expression in cortical neurons.

Brain-derived neurotrophic factor (BDNF), a member of the neurotrophin family, is deeply involved in the development and higher function of the nervous system, including learning and memory. By contrast, a reduction in BDNF levels is associated with various neurological disorders such as dementia and depression. Therefore, the inducers of Bdnf expression might be valuable in ameliorating or protecting against a decline in brain functions. We previously reported that, through high-throughput screening to identify inducers of Bdnf expression in Bdnf-luciferase transgenic mice, several herbal extracts induced Bdnf expression in cortical neurons. In the present study, we found that Panax notoginseng root extract (PNRE) potently induced Bdnf expression in primary cultured cortical neurons primarily via the L-type voltage-dependent Ca2+ channel (L-VDCC) and calcineurin. PNRE promoted nuclear translocation of cAMP-responsive element-binding protein-regulated transcription coactivator 1 (CRTC1). These findings suggest that PNRE activates the L-VDCC/calcineurin/CRTC1 axis, which is the primary signaling pathway involved in the neuronal activity-dependent expression of Bdnf. Moreover, we demonstrated that PNRE increased the dendritic complexity of cortical neurons in vitro. Thus, by upregulating Bdnf expression, PNRE is a potential candidate for improving cognitive impairment seen in several kinds of dementia.

Understanding the Role of Galectin-1 in Heart Failure: A Comprehensive Narrative Review.

Heart failure (HF) is the fastest-growing cardiovascular condition worldwide. The immune system may play a role in the development of HF since this condition is associated with elevated pro-inflammatory cytokine levels. HF is a life-threatening disease, and there is an increasing demand for diagnostic biomarkers, prognostic factors, and therapeutic agents that can help treat it. Galectin-1 (Gal-1) is the prototype galectin of the lectin family. Multiple signal transduction pathways are regulated by Ras proteins, which act as a molecular switch in cells. Gal-1 regulates T and B cell activation, differentiation, and survival. Gal-1 has been linked to inflammation. Activated T cells produce Gal-1 through an autocrine apoptotic mechanism involving MEK1/ERK and p38 MAPK. In the cardiovascular system, atherosclerosis is facilitated by Gal-1. Heart disease, myocardial infarction, hypertension, and stroke can be caused by atherosclerotic plaque. HF and heart hypertrophy are caused by decreased cardiac L-type Ca2+ channel activity. Deregulation of Gal-1 and CaV1.2 in pathological cardiac hypertrophy suggests a possible target for anti-hypertrophic therapy. Rat hypertrophic cardiomyocytes express Gal-1 and CaV1.2 channels simultaneously. It has been reported that diastolic dysfunction (DD) is associated with elevated Gal-1 levels. The high Gal-1 level in subjects led to the lowest cumulative survival as a composite endpoint. Incidences of HF, DD, and serum Gal-1 levels correlated significantly. The ejection fraction was negatively correlated with Gal-1 and CRP concentrations. Based on two different approaches in mice and humans, Gal-1 was identified as a potential mediator of HF.

Increased Risk for Atrial Alternans in Rabbit Heart Failure: The Role of Ca2+/Calmodulin-Dependent Kinase II and Inositol-1,4,5-trisphosphate Signaling.

Heart failure (HF) increases the probability of cardiac arrhythmias, including atrial fibrillation (AF), but the mechanisms linking HF to AF are poorly understood. We investigated disturbances in Ca2+ signaling and electrophysiology in rabbit atrial myocytes from normal and failing hearts and identified mechanisms that contribute to the higher risk of atrial arrhythmias in HF. Ca2+ transient (CaT) alternans-beat-to-beat alternations in CaT amplitude-served as indicator of increased arrhythmogenicity. We demonstrate that HF atrial myocytes were more prone to alternans despite no change in action potentials duration and only moderate decrease of L-type Ca2+ current. Ca2+/calmodulin-dependent kinase II (CaMKII) inhibition suppressed CaT alternans. Activation of IP3 signaling by endothelin-1 (ET-1) and angiotensin II (Ang II) resulted in acute, but transient reduction of CaT amplitude and sarcoplasmic reticulum (SR) Ca2+ load, and lowered the alternans risk. However, prolonged exposure to ET-1 and Ang II enhanced SR Ca2+ release and increased the degree of alternans. Inhibition of IP3 receptors prevented the transient ET-1 and Ang II effects and by itself increased the degree of CaT alternans. Our data suggest that activation of CaMKII and IP3 signaling contribute to atrial arrhythmogenesis in HF.

Nitric oxide and ion channels mediate L-cysteine-induced inhibition of colonic smooth muscle contraction.

Previous studies have suggested that L-cysteine regulates gut motility through hydrogen sulfide. However, the mechanisms involved in the L-cysteine-induced response have not been extensively studied. This study aimed to investigate the underlying mechanisms of action of L-cysteine on spontaneous contraction of rat colon. Longitudinal and circular muscle strips from rat middle colon were prepared to measure the spontaneous contractile activities of colon in an organ bath system. Whole-cell voltage-clamp techniques were applied to record the currents of L-type voltage-dependent Ca2+ channels (VDCCs) and voltage-gated K+ channels (Kv) in isolated smooth muscle cells (SMCs) from colon. L-cysteine inhibited the spontaneous contraction of longitudinal and circular muscle strips from the rat colon in a concentration-dependent manner. The inhibition induced by L-cysteine was significantly decreased by inhibitors of H2S synthesis (p < 0.05). Furthermore, the suppression induced by L-cysteine was partially attenuated by tetrodotoxin, L-NNA and glibenclamide (p < 0.05). Whole-cell voltage-clamp recordings showed that L-cysteine caused a remarkable reduction in the peak currents of VDCCs and significantly increased the membrane currents of Kv channels in isolated SMCs (p < 0.05). We concluded that L-cysteine inhibits the contractile activities of smooth muscle strips from the rat colon. The relaxation in response to L-cysteine may be in part mediated by a nitrergic pathway and by inhibiting the VDCCs in combination with a direct activation of the KV channels and KATP channels.

Allopregnanolone pleiotropic action in neurons and astrocytes: calcium signaling as a unifying mechanism.

Allopregnanolone (Allo) is a neurosteroid with pleiotropic action in the brain that includes neurogenesis, oligogenesis, human and rodent neural stem cell regeneration, increased glucose metabolism, mitochondrial respiration and biogenesis, improved cognitive function, and reduction of both inflammation and Alzheimer's disease (AD) pathology. Because the breadth of Allo-induced responses requires activation of multiple systems of biology in the absence of an Allo-specific nuclear receptor, analyses were conducted in both neurons and astrocytes to identify unifying systems and signaling pathways. Mechanisms of Allo action were investigated in embryonic hippocampal neurons and astrocytes cultured in an Aging Model (AM) media. Cellular morphology, mitochondrial function, and transcriptomics were investigated followed by mechanistic pathway analyses. In hippocampal neurons, Allo significantly increased neurite outgrowth and synaptic protein expression, which were paralleled by upregulated synaptogenesis and long-term potentiation gene expression profiles. Mechanistically, Allo induced Ca2+/CREB signaling cascades. In parallel, Allo significantly increased maximal mitochondrial respiration, mitochondrial membrane potential, and Complex IV activity while reducing oxidative stress, which required both the GABAA and L-type Ca2+ channels. In astrocytes, Allo increased ATP generation, mitochondrial function and dynamics while reducing oxidative stress, inflammasome indicators, and apoptotic signaling. Mechanistically, Allo regulation of astrocytic mitochondrial function required both the GABAA and L-type Ca2+ channels. Furthermore, Allo activated NRF1-TFAM signaling and increased the DRP1/OPA1 protein ratio, which led to increased mitochondrial biogenesis and dynamics. Collectively, the cellular, mitochondrial, transcriptional, and pharmacological profiles provide evidence in support of calcium signaling as a unifying mechanism for Allo pleiotropic actions in the brain.

MicroRNA-1 Deficiency Is a Primary Etiological Factor Disrupting Cardiac Contractility and Electrophysiological Homeostasis.

MicroRNA-1 (miR1), encoded by the genes miR1-1 and miR1-2, is the most abundant microRNA in the heart and plays a critical role in heart development and physiology. Dysregulation of miR1 has been associated with various heart diseases, where a significant reduction (>75%) in miR1 expression has been observed in patient hearts with atrial fibrillation or acute myocardial infarction. However, it remains uncertain whether miR1-deficiency acts as a primary etiological factor of cardiac remodeling. miR1-1 or miR1-2 knockout mice were crossbred to produce 75%-miR1-knockdown (75%KD; miR1-1+/-:miR1-2-/- or miR1-1-/-:miR1-2+/-) mice. Cardiac pathology of 75%KD cardiomyocytes/hearts was investigated by ECG, patch clamping, optical mapping, transcriptomic, and proteomic assays. In adult 75%KD hearts, the overall miR1 expression was reduced to ≈25% of the normal wild-type level. These adult 75%KD hearts displayed decreased ejection fraction and fractional shortening, prolonged QRS and QT intervals, and high susceptibility to arrhythmias. Adult 75%KD cardiomyocytes exhibited prolonged action potentials with impaired repolarization and excitation-contraction coupling. Comparatively, 75%KD cardiomyocytes showcased reduced Na+ current and transient outward potassium current, coupled with elevated L-type Ca2+ current, as opposed to wild-type cells. RNA sequencing and proteomics assays indicated negative regulation of cardiac muscle contraction and ion channel activities, along with a positive enrichment of smooth muscle contraction genes in 75%KD cardiomyocytes/hearts. miR1 deficiency led to dysregulation of a wide gene network, with miR1's RNA interference-direct targets influencing many indirectly regulated genes. Furthermore, after 6 weeks of bi-weekly intravenous tail-vein injection of miR1 mimics, the ejection fraction and fractional shortening of 75%KD hearts showed significant improvement but remained susceptible to arrhythmias. miR1 deficiency acts as a primary etiological factor in inducing cardiac remodeling via disrupting heart regulatory homeostasis. Achieving stable and appropriate microRNA expression levels in the heart is critical for effective microRNA-based therapy in cardiovascular diseases.

Adrenoceptors in GtoPdb v.2023.3

The nomenclature of the Adrenoceptors has been agreed by the NC-IUPHAR Subcommittee on Adrenoceptors [64, 194]. Adrenoceptors, α1 The three α1-adrenoceptor subtypes α1A, α1B and α1D are activated by the endogenous agonists (-)-adrenaline and (-)-noradrenaline. -(-)phenylephrine, methoxamine and cirazoline are agonists and prazosin and doxazosin antagonists considered selective for α1- relative to α2-adrenoceptors. [3H]prazosin and [125I]HEAT (BE2254) are relatively selective radioligands. S(+)-niguldipine also has high affinity for L-type Ca2+ channels. Fluorescent derivatives of prazosin (Bodipy FLprazosin- QAPB) are used to examine cellular localisation of α1-adrenoceptors. α1-Adrenoceptor agonists are used as nasal decongestants; antagonists to treat symptoms of benign prostatic hyperplasia (alfuzosin, doxazosin, terazosin, tamsulosin and silodosin, with the last two compounds being α1A-adrenoceptor selective and claiming to relax bladder neck tone with less hypotension); and to a lesser extent hypertension (doxazosin, terazosin). The α1- and β2-adrenoceptor antagonist carvedilol is used to treat congestive heart failure, although the contribution of α1-adrenoceptor blockade to the therapeutic effect is unclear. Several anti-depressants and anti-psychotic drugs are α1-adrenoceptor antagonists contributing to side effects such as orthostatic hypotension. Adrenoceptors, α2The three α2-adrenoceptor subtypes α2A, α2B and α2C are activated by (-)-adrenaline and with lower potency by (-)-noradrenaline. brimonidine and talipexole are agonists and rauwolscine and yohimbine antagonists selective for α2- relative to α1-adrenoceptors. [3H]rauwolscine, [3H]brimonidine and [3H]RX821002 are relatively selective radioligands. There are species variations in the pharmacology of the α2A-adrenoceptor. Multiple mutations of α2-adrenoceptors have been described, some associated with alterations in function. Presynaptic α2-adrenoceptors regulate many functions in the nervous system. The α2-adrenoceptor agonists clonidine, guanabenz and brimonidine affect central baroreflex control (hypotension and bradycardia), induce hypnotic effects and analgesia, and modulate seizure activity and platelet aggregation. clonidine is an anti-hypertensive (relatively little used) and counteracts opioid withdrawal. dexmedetomidine (also xylazine) is increasingly used as a sedative and analgesic in human [33] and veterinary medicine and has sympatholytic and anxiolytic properties. The α2-adrenoceptor antagonist mirtazapine is used as an anti-depressant. The α2B subtype appears to be involved in neurotransmission in the spinal cord and α2C in regulating catecholamine release from adrenal chromaffin cells. Although subtype-selective antagonists have been developed, none are used clinically and they remain experimental tools. Adrenoceptors, β The three β-adrenoceptor subtypes β1, β2 and β3 are activated by the endogenous agonists (-)-adrenaline and (-)-noradrenaline. Isoprenaline is selective for β-adrenoceptors relative to α1- and α2-adrenoceptors, while propranolol (pKi 8.2-9.2) and cyanopindolol (pKi 10.0-11.0) are relatively selective antagonists for β1- and β2- relative to β3-adrenoceptors. (-)-noradrenaline, xamoterol and (-)-Ro 363 show selectivity for β1- relative to β2-adrenoceptors. Pharmacological differences exist between human and mouse β3-adrenoceptors, and the 'rodent selective' agonists BRL 37344 and CL316243 have low efficacy at the human β3-adrenoceptor whereas CGP 12177 (low potency) and L 755507 activate human β3-adrenoceptors [88]. β3-Adrenoceptors are resistant to blockade by propranolol, but can be blocked by high concentrations of bupranolol. SR59230A has reasonably high affinity at β3-adrenoceptors, but does not discriminate between the three β- subtypes [332] whereas L-748337 is more selective. [125I]-cyanopindolol, [125I]-hydroxy benzylpindolol and [3H]-alprenolol are high affinity radioligands that label β1- and β2- adrenoceptors and β3-adrenoceptors can be labelled with higher concentrations (nM) of [125I]-cyanopindolol together with β1- and β2-adrenoceptor antagonists. Fluorescent ligands such as BODIPY-TMR-CGP12177 can be used to track β-adrenoceptors at the cellular level [8]. Somewhat selective β1-adrenoceptor agonists (denopamine, dobutamine) are used short term to treat cardiogenic shock but, chronically, reduce survival. β1-Adrenoceptor-preferring antagonists are used to treat cardiac arrhythmias (atenolol, bisoprolol, esmolol) and cardiac failure (metoprolol, nebivolol) but also in combination with other treatments to treat hypertension (atenolol, betaxolol, bisoprolol, metoprolol and nebivolol) [528]. Cardiac failure is also treated with carvedilol that blocks β1- and β2-adrenoceptors, as well as α1-adrenoceptors. Short (salbutamol, terbutaline) and long (formoterol, salmeterol) acting β2-adrenoceptor-selective agonists are powerful bronchodilators used to treat respiratory disorders. Many first generation β-adrenoceptor antagonists (propranolol) block both β1- and β2-adrenoceptors and there are no β2-adrenoceptor-selective antagonists used therapeutically. The β3-adrenoceptor agonist mirabegron is used to control overactive bladder syndrome. There is evidence to suggest that β-adrenoceptor antagonists can reduce metastasis in certain types of cancer [197].

Nutrient-Sensitising Drug Repurposing Screen Identifies Lomerizine As a Mitochondrial Metabolism Inhibitor in Chronic Myeloid Leukaemia

In chronic myeloid leukaemia (CML), the persistence of leukaemic stem cells (LSCs) following first line treatment with tyrosine kinase inhibitors (TKIs) such as imatinib, can lead to disease relapse. We have previously demonstrated that therapy-resistant CML LSCs rely on oxidative phosphorylation (OXPHOS) for survival and that targeting mitochondrial metabolism sensitises CML LSCs to imatinib treatment. However, current OXPHOS inhibitors have demonstrated limited efficacy, or are associated with adverse effects in clinical trials, highlighting that identification of clinically safe oxidative pathway inhibitors is warranted. To identify clinically applicable compounds that target cells dependent on mitochondrial metabolism, we used a nutrient-sensitised repurposing screening strategy. Upon replacement of glucose with galactose as the only sugar source in cell culture media, there is a shift in cellular metabolism towards OXPHOS (as cells are unable to effectively use galactose for glycolysis). Therefore, CML cells grown in galactose-containing media are more sensitive to inhibition of mitochondrial respiration than glucose-grown cells. Using this approach, we screened total of &amp;gt;1,100 unique and structurally diverse FDA-approved drugs in CML cells, cultured in the presence of 11mM glucose or 11mM galactose. This uncovered lomerizine dihydrochloride, a L-type Ca2+ channel blocker used as an anti-migraine drug, as a candidate compound effective against OXPHOS-dependent CML cells. Subsequently, patient derived CML CD34+ cells were shown to have increased ER mass (the main intracellular Ca2+ store) and an increase in mitochondrial Ca2+ levels compared with normal cells. Moreover, transcriptional analysis revealed that Ca2+ channel genes such as voltage-gated CACNA1D and receptor-activated TRPC6 are significantly upregulated in CML LSCs (CD34+CD38-) when compared with normal haematopoietic stem cells (HSCs), which was not reverted following imatinib treatment. Therefore, we hypothesised that the observed increase in mitochondrial metabolism in CML LSCs was dependent on CACNA1D and TRPC6 activity, and the increase in mitochondrial Ca2+ levels, which could be inhibited by lomerizine treatment. Notably, CRISPR-Cas9-mediated CACNA1D or TRPC6 knockout significantly reduced cytoplasmic and mitochondrial Ca2+ levels, and decreased cellular oxygen consumption rate, indicative of reduction in OXPHOS. Similarly, while imatinib treatment did not affect intracellular Ca2+ levels in primary CML CD34+ cells, lomerizine treatment significantly reduced cytoplasmic and mitochondrial Ca2+ levels, and mitochondrial respiration/OXPHOS. Applying liquid chromatography-mass spectrometry and isotope assisted metabolomics, we traced labelled nutrients (glucose and palmitate) in CD34+ cells. This revealed a significant reduction in activity of mitochondria-located Ca2+ dependent dehydrogenases and overall reduction in tricarboxylic acid (TCA) cycle activity in primary CML cells following lomerizine treatment. Of clinical relevance, using combination of cell surface markers, cell division trackers and functional assays, including long-term culture initiating cell (LTC-IC) assay, we demonstrate that lomerizine treatment, alone or in combination with imatinib, targeted CML LSCs when cultured in physiological medium in vitro, without affecting normal HSCs. Notably, combination treatment with imatinib and lomerizine reduced CML tumour burden, targeted CML LSCs and extended survival in xenotransplantation model of human CML. In summary, we reveal for the first time that Ca2+ regulation is disrupted in CML stem cells and influx via CACNA1D and TRPC6 is crucial for maintaining high mitochondrial Ca2+ levels and enhanced mitochondrial OXPHOS. This renders CML stem cells sensitive to lomerizine, an FDA-approved Ca2+ inhibitor identified following metabolism-specific drug-repurposing screening.

An increase in intercellular crosstalk and electrotonic coupling between cardiomyocytes and nonmyocytes reshapes the electrical conduction in the metabolic heart characterized by short QT intervals in ECGs.

Cardiac conduction abnormalities are disorders in metabolic syndrome (MetS), however, their mechanisms are unknown. Although ventricular arrhythmia reflects the changes in QT-interval of electrocardiograms associated with the changes in cardiomyocyte action potential durations (APDs), recent studies emphasize role of intercellular crosstalk between cardiomyocytes and nonmyocytes via passive (electrotonic)-conduction. Therefore, considering the possible increase in intercellular interactions of nonmyocytes with cardiomyocytes, we hypothesized an early-cardiac-remodeling characterized by short QT-interval via contributions and modulations of changes by nonmyocytes to the ventricular APs in an early-stage MetS hearts. Following the feeding of 8-week-old rats with a high-sucrose diet (32%; MetS rats) and validation of insulin resistance, there was a significant increase in heart rate and changes in the electrical characteristics of the hearts, especially a shortening in action potential (AP) duration of the papillary muscles. The patch-clamp analysis of ventricular cardiomyocytes showed an increase in the Na+ -channel currents while there were decreases in l-type Ca2+ -channel (LTCC) currents with unchanged K+ -channel currents. There was an increase in the phosphorylated form of connexin 43 (pCx43), mostly with lateral localization on sarcolemma, while its unphosphorylated form (Cx43) exhibited a high degree of localization within intercalated discs. A high-level positively-stained α-SMA and CD68 cells were prominently localized and distributed in interfibrillar spaces of the heart, implying the possible contributions of myofibroblasts and macrophages to both shortened APDs and abnormal electrical conduction in MetS hearts. Our data propose a previously unrecognized pathway for SQT induction in the heart. This pathway includes not only the contribution of short ventricular-APDs via ionic mechanisms but also increasing contributions of the electrotonic-cardiomyocyte depolarization, spontaneous electrical activity-associated fast heterogeneous impulse conduction in the heart via increased interactions and relocations between cardiomyocytes and nonmyocytes, which may be an explanation for the development of an SQT in early-cardiac-remodeling.

Simvastatin, but not Pravastatin, Blocks L-Type Ca2+ Channels In Rat Islet -Cells, Inhibiting Glucose-Induced Cytosolic Ca2+ Signaling and Insulin Release

Patients with type 2 diabetes who have hypercholesterolemia frequently need to take HMG-CoA reductase inhibitors. A key factor in the pathophysiology of type 2 diabetes is altered pancreatic beta-cell activity, which results in a reduced ability of the pancreas to secrete insulin in response to glucose. The impact of HMG-CoA reductase inhibitors on -cell function must therefore be investigated. The regulation of -cell function is greatly influenced by the cytosolic Ca2+ concentration ([Ca2+]i). The current work looked at how HMG-CoA reductase inhibitors affected the [Ca2+]i signaling and insulin release that glucose-induced in rat islet -cells. Simvastatin, a lipophilic HMG-CoA reductase inhibitor, suppressed the initial phase increase and oscillation of [Ca2+]i caused by 8.3 mM glucose in single -cells at concentrations ranging from 0.1 to 3 g ml—1. The fewer Simvastatin-acid, a lipophilic inhibitor, decreased the first [Ca2+]i rise but was two orders of magnitude less effective. Pravastatin (100g ml—1), a hydrophilic inhibitor, has little impact on [Ca2+]. Simvastatin (0.3g ml–1) reduced glucose-induced insulin production from islets more effectively than simvastatin-acid (30g ml–1), whereas pravastatin (100g ml–1) had no effect. Simvastatin, but not pravastatin, showed a reversible blockage of the L-type Ca2+ channels in -cells in whole-cell patch clamp recordings. Simvastatin also prevented the opening of L-type Ca2+ channels, which is how L-arginine and HCl enhance [Ca2+] Conclusion: By blocking L-type Ca2+ channels in -cells, lipophilic HMG-CoA reductase inhibitors can prevent glucose-induced [Ca2+]i signaling and insulin secretion, and their inhibitory potencies are inversely correlated with their lipophilicities. Precaution must be takenWhen HMG-CoA reductase inhibitors are utilized in clinical settings, attention should be given to these findings, especially in type 2 diabetic patients.

CaV3.1 channels facilitate calcium wave generation and myogenic tone development in mouse mesenteric arteries

The arterial myogenic response to intraluminal pressure elicits constriction to maintain tissue perfusion. Smooth muscle [Ca2+] is a key determinant of constriction, tied to L-type (CaV1.2) Ca2+ channels. While important, other Ca2+ channels, particularly T-type could contribute to pressure regulation within defined voltage ranges. This study examined the role of one T-type Ca2+ channel (CaV3.1) using C57BL/6 wild type and CaV3.1−/− mice. Patch-clamp electrophysiology, pressure myography, blood pressure and Ca2+ imaging defined the CaV3.1−/− phenotype relative to C57BL/6. CaV3.1−/− mice had absent CaV3.1 expression and whole-cell current, coinciding with lower blood pressure and reduced mesenteric artery myogenic tone, particularly at lower pressures (20–60 mmHg) where membrane potential is hyperpolarized. This reduction coincided with diminished Ca2+ wave generation, asynchronous events of Ca2+ release from the sarcoplasmic reticulum, insensitive to L-type Ca2+ channel blockade (Nifedipine, 0.3 µM). Proximity ligation assay (PLA) confirmed IP3R1/CaV3.1 close physical association. IP3R blockade (2-APB, 50 µM or xestospongin C, 3 µM) in nifedipine-treated C57BL/6 arteries rendered a CaV3.1−/− contractile phenotype. Findings indicate that Ca2+ influx through CaV3.1 contributes to myogenic tone at hyperpolarized voltages through Ca2+-induced Ca2+ release tied to the sarcoplasmic reticulum. This study helps establish CaV3.1 as a potential therapeutic target to control blood pressure.

BK channels sustain neuronal Ca2+ oscillations to support hippocampal long-term potentiation and memory formation

Mutations of large conductance Ca2+- and voltage-activated K+ channels (BK) are associated with cognitive impairment. Here we report that CA1 pyramidal neuron-specific conditional BK knock-out (cKO) mice display normal locomotor and anxiety behavior. They do, however, exhibit impaired memory acquisition and retrieval in the Morris Water Maze (MWM) when compared to littermate controls (CTRL). In line with cognitive impairment in vivo, electrical and chemical long-term potentiation (LTP) in cKO brain slices were impaired in vitro. We further used a genetically encoded fluorescent K+ biosensor and a Ca2+-sensitive probe to observe cultured hippocampal neurons during chemical LTP (cLTP) induction. cLTP massively reduced intracellular K+ concentration ([K+]i) while elevating L-Type Ca2+ channel- and NMDA receptor-dependent Ca2+ oscillation frequencies. Both, [K+]i decrease and Ca2+ oscillation frequency increase were absent after pharmacological BK inhibition or in cells lacking BK. Our data suggest that L-Type- and NMDAR-dependent BK-mediated K+ outflow significantly contributes to hippocampal LTP, as well as learning and memory.

Ketogenic Diet Regulates Cardiac Remodeling and Calcium Homeostasis in Diabetic Rat Cardiomyopathy.

A ketogenic diet (KD) might alleviate patients with diabetic cardiomyopathy. However, the underlying mechanism remains unclear. Myocardial function and arrhythmogenesis are closely linked to calcium (Ca2+) homeostasis. We investigated the effects of a KD on Ca2+ homeostasis and electrophysiology in diabetic cardiomyopathy. Male Wistar rats were created to have diabetes mellitus (DM) using streptozotocin (65 mg/kg, intraperitoneally), and subsequently treated for 6 weeks with either a normal diet (ND) or a KD. Our electrophysiological and Western blot analyses assessed myocardial Ca2+ homeostasis in ventricular preparations in vivo. Unlike those on the KD, DM rats treated with an ND exhibited a prolonged QTc interval and action potential duration. Compared to the control and DM rats on the KD, DM rats treated with an ND also showed lower intracellular Ca2+ transients, sarcoplasmic reticular Ca2+ content, sodium (Na+)-Ca2+ exchanger currents (reverse mode), L-type Ca2+ contents, sarcoplasmic reticulum ATPase contents, Cav1.2 contents. Furthermore, these rats exhibited elevated ratios of phosphorylated to total proteins across multiple Ca2+ handling proteins, including ryanodine receptor 2 (RyR2) at serine 2808, phospholamban (PLB)-Ser16, and calmodulin-dependent protein kinase II (CaMKII). Additionally, DM rats treated with an ND demonstrated a higher frequency and incidence of Ca2+ leak, cytosolic reactive oxygen species, Na+/hydrogen-exchanger currents, and late Na+ currents than the control and DM rats on the KD. KD treatment may attenuate the effects of DM-dysregulated Na+ and Ca2+ homeostasis, contributing to its cardioprotection in DM.

Abstract 11591: Mechanism of Finerenone-Induced Vasorelaxation in Arteries From Human Visceral Adipose Tissue

Introduction: Inadequate perfusion has emerged as a main determinant of adipose tissue (AT) dysfunction in obesity, sparking interest about possible ways to improve it. Among several mechanisms, mineralcorticoid receptor (MR) signaling has been shown to play a key role in the cross-talk between AT and the vasculature. Hypothesis: This study, therefore, tested the vasoactive properties of finerenone, a nonsteroidal MR antagonist, in arteries harvested from human AT. Methods: Small arteries (&lt;1 mm in diameter) were isolated from visceral AT and studied ex vivo in a wire myograph. After vessels had been contracted, changes in vascular tone were determined under different experimental conditions. Results: Finerenone elicited a concentration-dependent relaxation in arteries of obese individuals contracted with the thromboxane A2 analogue U46619 (n=9; P&lt;0001 vs. baseline); the steroidal MR antagonist potassium canrenoate, by contrast, did not induce any vasorelaxation (n=3; P&gt;0.05). The relaxing effect of finerenone on U46619-induced constriction was not different in arteries from lean (n=3) and obese subjects (P=0.155). Mechanistically, the vasorelaxing response to finerenone was not influenced by pre-incubation with the nitric oxide (NO) synthase inhibitor L-NAME (n=4; P=0.19 vs. saline), hence ruling out an involvement of NO. Interestingly, finerenone was also able to relax arteries contracted with endothelin-1 (n=7; P&lt;0.001) or with high-K + solution (n=4; P&lt;0001), as well as those contracted with the L-type Ca 2+ -channel agonist BayK8644 (n=5; P=0.007); similarly, the calcium-channel blocker nifedipine induced relaxation of arteries contracted with BayK8644 (n=3; P&lt;0.001). Conclusions: Finerenone induces NO-independent vasorelaxation in arterioles from human visceral AT, likely through antagonism of L-type Ca2 + -channels. This finding identifies a novel action of finerenone to improve AT perfusion, thereby potentially expanding the emerging observations about the cardiovascular benefits of this agent.

PP121, a dual inhibitor of tyrosine and phosphoinositide kinases, relieves airway hyperresponsiveness, mucus hypersecretion and inflammation in a murine asthma model

BackgroundTyrosine kinase and phosphoinositide kinase pathways play important roles in asthma formation. As a dual tyrosine and phosphoinositide kinase inhibitor, PP121 has shown anticancer efficacy in multiple tumors. However, the study of PP121 in pulmonary diseases is still limited. Herein, we investigated the therapeutic activities of PP121 in asthma treatment.MethodsTension measurements and patch clamp recordings were made to investigate the anticontractile characteristics of PP121 in vitro. Then, an asthma mouse model was established to further explore the therapeutic characteristics of PP121 via measurement of respiratory system resistance, histological analysis and western blotting.ResultsWe discovered that PP121 could relax precontracted mouse tracheal rings (mTRs) by blocking certain ion channels, including L-type voltage-dependent Ca2+ channels (L-VDCCs), nonselective cation channels (NSCCs), transient receptor potential channels (TRPCs), Na+/Ca2+ exchangers (NCXs) and K+ channels, and accelerating calcium mobilization. Furthermore, PP121 relieved asthmatic pathological features, including airway hyperresponsiveness, systematic inflammation and mucus secretion, via downregulation of inflammatory factors, mucins and the mitogen-activated protein kinase (MAPK)/Akt signaling pathway in asthmatic mice.ConclusionIn summary, PP121 exerts dual anti-contractile and anti-inflammatory effects in asthma treatment, which suggests that PP121 might be a promising therapeutic compound and shed new light on asthma therapy.

Graphene Oxide-Mediated Regulation of Volume Exclusion and Wettability in Biomimetic Phosphorylation-Responsive Ionic Gates.

Replicating phosphorylation-responsive ionic gates via artificial fluidic systems is essential for biomolecular detection and cellular communication research. However, current approaches to governing the gates primarily rely on volume exclusion or surface charge modulation. To overcome this limitation and enhance ion transport controllability, we introduce graphene oxide (GO) into nanochannel systems, simultaneously regulating the volume exclusion and wettability. Moreover, inspired by (cAMP)-dependent protein kinase A (PKA)-regulated L-type Ca2+ channels, we employ peptides for phosphorylation which preserves them as nanoadhesives to coat nanochannels with GO. The coating boosts steric hindrance and diminishes wettability, creating a substantial ion conduction barrier, which represents a significant advancement in achieving precise ion transport regulation in abiotic nanochannels. Leveraging the mechanism, we also fabricated a sensitive biosensor for PKA activity detection and inhibition exploration. The combined regulation of volume exclusion and wettability offers an appealing strategy for controlled nanofluidic manipulation with promising biomedical applications in diagnosis and drug discovery.