Inhibition Of Calcium Channels Research Articles

Ethyl chloride poisoning from inhalational misuse: clinical features and outcomes

Introduction Ethyl chloride misuse remains a prevailing concern due to its accessibility, but detailed descriptions of the features of toxicity are limited to sporadic reports, resulting in knowledge gaps in their clinical features and diagnosis. Objective To describe the clinical features, treatment, and outcomes of patients reported in the literature who developed toxicity from inhalational use of ethyl chloride. Methods We reviewed relevant literature over the past 50 years and analyzed the characteristics and outcomes of patients with toxicity from the inhalational use of ethyl chloride. Results A total of 21 studies from 1979 to 2024 were identified, making available 22 patients for analysis. Their median age was 40 years (range 16–62 years), and there were more than four times as many males as females. Ethyl chloride-containing cleaning solvents (8/22, 36%) were most commonly used. Regular inhalation of ethyl chloride was documented in approximately two-thirds of the patients (14/22, 66%), with a median duration of five months of misuse (range 2–360 months). A large proportion of patients (15/22, 68%) inhaled ethyl chloride again within a week from the onset of toxicity. Although features of cerebellar dysfunction were very common at presentation (13/16, 81%), abnormalities on neuroimaging studies were rare. Death occurred in more than a quarter of cases (6/22, 27%), with patients either already deceased or dying shortly after. Half (3/6) of these deaths were directly attributable to the development of lethal cardiac dysrhythmias. Conversely, most survivors either improved or fully recovered within a few days to weeks (14/16, 88%), independent of their presenting symptoms, clinical signs, and the treatments they received. Discussion Ethyl chloride users are likely young or middle-aged males, and clinical features of toxicity can range from transient neurological symptoms to cardiac dysrhythmias and death. The prominence of neurotoxicity may be attributed to the lipophilic nature of ethyl chloride and its tendency to accumulate in neural tissue, while cardiac dysrhythmias have been attributed to cardiac sensitization to catecholamines through ethyl chloride-induced inhibition of potassium, calcium, and sodium channels. Conclusions Toxicity from the inhalational misuse of ethyl chloride should be considered in young or middle-aged males presenting with acute cerebellar dysfunction. We recommend that suspected cases undergo telemetric monitoring for 24 h, especially when tachycardia and/or palpitations are present, as deaths from lethal cardiac dysrhythmias are not uncommon.

Oxygenation Effects of Antihypertensive Agents in Intensive Care: A Prospective Comparative Study of Nicardipine and Urapidil.

Acute arterial hypertension within the critical care context may necessitate the administration of intravenous antihypertensive agents. Nicardipine and urapidil are notable for their application in intensive care units. Nonetheless, dihydropyridine calcium channel inhibitors (DCCIs) such as nicardipine are implicated in the impairment of hypoxic pulmonary vasoconstriction, potentially disrupting oxygenation. This study aimed to assess the differences in patient oxygenation when these antihypertensive agents are administered intravenously. This bicentric, prospective, observational investigation spanning five intensive care units evaluated patients requiring intravenous nicardipine or urapidil. Oxygenation data were recorded from the start of therapy until the 12th hour. Comparative analysis was performed between patient groups based on the antihypertensive agent administered, along with subgroup investigations to identify populations with an elevated risk of hypoxemia. From November 2021 to November 2023, 197 patients were included: 98 (50%) were treated with nicardipine, and 99 (50%) were treated with urapidil. Hypoxemia occurred in 97 (49%) patients and was more prevalent in the nicardipine cohort, affecting 65 (66%) patients, as opposed to 32 (32%) patients in the urapidil cohort (RR 2.05, 95% CI [1.48-2.82], P < 0.001). Subgroup analysis revealed a significant association between patients with pulmonary atelectasis (RR 2.30, 95% CI [1.4-3.7], P < 0.001) and obesity (RR 2.7, 95% CI [1.5-4.6], P < 0.001). Considering these findings, cautious consideration of the patient's respiratory status should be exercised when initiating intravenous DCCI treatment. However, given the limitations of this study, a controlled trial on hypertension management in the ICU is needed.

Application of TCM network pharmacology and experimental verification to explore the mechanism of kaempferol against epilepsy

BackgroundKaempferol (KF), the main active ingredient in identifying the authenticity of safflower, has a variety of pharmacological activities and neuroprotective effects. However, the mechanism of KF in the treatment of epilepsy remains unclear. This study aimed to investigate the protective effects of KF on epilepsy and its related mechanisms. MethodsNetwork pharmacology was used to explore the targets and mechanisms of safflower antiepileptic action. The protective effect of KF on epilepsy was assessed in the behavior and tissues of epileptic mice. Additionally, the impact of KF on the excitability and calcium transients of rat cortical neurons and α-amino-3-hydroxy-5-methyl-4-isoxazole-propionicacid receptor (AMPAR) were investigated using patch clamp and calcium imaging techniques. ResultsNetwork pharmacology indicated safflower could be involved in calcium signaling pathways and calcium channel inhibitor activity. Experimental validation demonstrated that KF delayed seizure onset and mitigated neuronal damage in the prefrontal cortex of mice. It also reduced neuronal excitability, as indicated by action potential parameters, and suppressed Glutamate (Glu)-induced calcium transients. In tsA201 cells, KF inhibited AMPAR-mediated currents, suggesting a role in regulating [Ca2+]i homeostasis. ConclusionThese results indicate that KF's anticonvulsant properties may arise from its neuroprotection against cell injury, edema, and necrosis, its reduction of neuronal hyperexcitability, and its prevention of calcium-induced cytotoxicity, potentially involving AMPAR modulation. This study positions KF as a promising candidate for epilepsy therapy, offering a scientific foundation for its clinical investigation.

Calcium Channel Blocker Lacidipine Promotes Antitumor Immunity by Reprogramming Tryptophan Metabolism

AbstractDysfunction of calcium channels is involved in the development and progression of some cancers. However, it remains unclear the role of calcium channel inhibitors in tumor immunomodulation. Here, calcium channel blocker lacidipine is identified to potently inhibit the enzymatic activity and expression of indoleamine 2,3‐dioxygenase 1 (IDO1), a rate‐limiting enzyme in tryptophan metabolism. Lacidipine activates effector T cells and incapacitates regulatory T cells (Tregs) to augment the anti‐tumor effect of chemotherapeutic agents in breast cancer by converting immunologically “cold” into “hot” tumors. Mechanistically, lacidipine targets calcium channels (CaV1.2/1.3) to inhibit Pyk2‐JAK1‐calmodulin complex‐mediated IDO1 transcription suppression, which suppresses the kynurenine pathway and maintains the total nicotinamide adenine dinucleotide (NAD) pool by regulating NAD biosynthesis. These results reveal a new function of calcium channels in IDO1‐mediated tryptophan metabolism in tumor immunity and warrant further development of lacidipine for the metabolic immunotherapy in breast cancer.

Selective inhibition of T-type calcium channel preserves ischemic pre-conditioning mediated neuroprotection during cerebral ischemia reperfusion injury in diabetic mice.

Ischemic preconditioning (IPC) provides ischemic tolerance and neuroprotection during cerebral ischemia reperfusion (CI/R) injury. Diabetes abolishes the beneficial effects of conditioning phenomenon during CI/R. The study investigates the role of T-type calcium ion channel in IPC mediated protection during diabetes mellitus. The study employed Swiss Albino mice. Animals were divided into 3 normoglycaemic groups (Sham, CI/R, and IPC) and 4 hyperglycaemic groups (Sham, CI/R, IPC, and ML218 + IPC). CI/R injury was induced in Swiss Albino mice by occlusion of common carotid arteries followed by reperfusion. IPC was given prior to CI/R injury and diabetes was induced using streptozotocin (STZ). Animals were assessed for learning, memory, motor coordination, neurological function, cerebral infarction, edema, and histopathological alterations. Biochemical assessments were performed for calcium binding proteins (Calmodulin (CaM), calcium/calmodulin-dependent protein kinase II (CaMKII), and S100B), oxidative stress (4-hydroxy-2-nonenal (4-HNE)), glutathione (GSH), inflammation (nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB), tumor necrosis factor (TNF-α), interleukin (IL-10)), inducible nitric oxide synthase (iNOS) levels, and acetylcholinesterase activity (AChE) in brain supernatants. NF-kB, iNOS, and S100B serum levels were also assessed. CI/R animals (normoglycemic and hyperglycaemic) showed impairment in learning, memory, motor coordination, and neurological function along with increase in cerebral infarction, edema, and histopathological alterations. Furthermore, increase in brain calcium-binding proteins, oxidative stress, inflammation, and AChE along with serum NF-kB, iNOS, and S100B levels were recorded in CI/R animals. IPC ameliorated CI/R induced behavioral, biochemical, and histopathological impairment, however no beneficial effects were observed in IPC (diabetic) mice. Administration of ML218 (10mg/kg; i.p.), a selective T-type calcium channel re-established the IPC mediated neuroprotection in CI/R diabetic animals. In conclusion, IPC-mediated neuroprotection was abolished in diabetic mice. T-type calcium ion channel antagonism plays an important role in the IPC-mediated neuroprotection during hyperglycaemia.

Influence of intestinal microbiota on the metabolism of main cardiotropic drugs

The intestinal microbiota is one of the most important pathogenetic links in the development of cardiovascular diseases. Every year the world scientific community finds new interactions at the level of signaling molecules, metabolites and microorganisms, identifying more and more patterns and cause-and-effect relationships which indicate the commonality of the intestinal microbiota (GM) and cardiovascular diseases. The state of the host's intestinal community, its qualitative and quantitative composition, directly and indirectly affects the fundamental pathogenetic mechanisms of the development of cardiovascular diseases. Despite the fact that there are scientifically based methods of treatment, cardiovascular diseases remain the leading cause of death in the world. This phenomenon is partly due to wide variations in individual response to cardiovascular drugs. The pharmacological effects of cardiotropic drugs are quite different even within groups of patients comparable in age and gender. Every year intestinal microbiota is more and more evident to be responsible for this intraspecific variability. Gut microbes influence drug metabolism in several pharmacokinetic ways, and conversely, drugs can have significant effects on the microbiome and therefore pharmacodynamic processes. Drugs can alter the gut microenvironment and microbial metabolism, influence bacterial growth, thereby changing the composition and functions of the microbial community. One of the most important functions of GM, related to “intestinal-cardiovascular system”, is participation in the metabolism of major cardiotropic medications, such as digoxin, statins, ezetimibe, antithrombotic drugs, calcium channel blockers (CCBs), beta blockers (BB), gliflozins and inhibitors of the renin-angiotensin-aldosterone system (RAAS).

Distribution and calcium signaling function of somatostatin receptor subtypes in rat pituitary

The somatostatin (SST) receptor family controls pituitary hormone secretion, but the distribution and specific roles of these receptors on the excitability and voltage-gated calcium signaling of hormone producing pituitary cells have not been fully characterized. Here we show that the rat pituitary gland expressed Sstr1, Sstr2, Sstr3, and Sstr5 receptor genes in a cell type-specific manner: Sstr1 and Sstr2 in thyrotrophs, Sstr3 in gonadotrophs and lactotrophs, Sstr2, Sstr3, and Sstr5 in somatotrophs, and none in corticotrophs and melanotrophs. Most gonadotrophs and thyrotrophs spontaneously fired high-amplitude single action potentials, which were silenced by SST without affecting intracellular calcium concentrations. In contrast, lactotrophs and somatotrophs spontaneously fired low-amplitude plateau-bursting action potentials in conjunction with calcium transients, both of which were silenced by SST. Moreover, SST inhibited GPCR-induced voltage-gated calcium signaling and hormone secretion in all cell types expressing SST receptors, but the inhibition was more pronounced in somatotrophs. The pattern of inhibition of electrical activity and calcium signaling was consistent with both direct and indirect inhibition of voltage-gated calcium channels, the latter being driven by cell type-specific hyperpolarization. These results indicate that the action of SST in somatotrophs is enhanced by the expression of several types of SST receptors and their slow desensitization, that SST may play a role in the electrical resynchronization of gonadotrophs, thyrotrophs, and lactotrophs, and that the lack of SST receptors in corticotrophs and melanotrophs keeps them excitable and ready to responses to stress.

Mouse liver blood flow is regulated by hepatic stellate cells in response to the sympathetic neurotransmitter norepinephrine

BackgroundThere is no clear information on the regulation of liver blood flow by the autonomic nervous system. We conducted this study to investigate whether quiescent hepatic stellate cells (qHSCs) regulate liver blood flow in response to the sympathetic neurotransmitter norepinephrine (NE). MethodsqHSCs isolated from mice were cultured in Dulbecco's modified Eagle medium without fetal bovine serum for 1 day on collagen gel. NE-induced qHSC contraction was evaluated using the quantitative single-cell contraction measurement method that we had developed previously. For the measurement of liver perfusion pressure in situ, a buffer solution was perfused from the portal vein in mice. ResultsNE-induced a reversible contraction of qHSCs. This contraction was suppressed by the nonmuscle myosin II inhibitor blebbistatin, the myosin light chain kinase inhibitor ML-9, the Rho kinase inhibitor H-1152, the calmodulin inhibitor W-7, the store-operated calcium channel inhibitor YM-58483, and the IP3 receptor inhibitor xestospongin C. In contrast, the transient receptor potential C channel inhibitor SKF96365 did not affect the NE-induced contraction. ConclusionThese results suggest that qHSCs contract in response to NE. New & noteworthyThe present study provides direct evidence for the first time that norepinephrine (NE) induces a reversible contraction of isolated single quiescent hepatic stellate cells (qHSCs) and further suggests that the NE-mediated qHSC contraction participates in the regulation of liver blood flow in vivo.

Interaction of some chalcone derivatives with calcium channels using a theoretical model

For several years, different drugs have been used to treat heart failure, such as digoxin, captopril, spironolactone, milrinone, levosimedam, dobutamine, and others. However, some of these drugs can produce secondary effects such as arrhythmia, cough, hyperkalemia, and others. Analyzing these data, this study aimed to evaluate the interaction of some chalcone derivatives (1-17) with calcium channels using theoretical models. It is important to mention that 7pjx protein, nifedipine, amlodipine, diltiazem, and verapamil were used as theoretical tools in the DockingServer program. The results showed differences in the interaction of chalcone derivatives compared with nifedipine, amlodipine, diltiazem, and verapamil drugs. Other data indicate that the inhibition constant (Ki) for chalcone analog 1 was lower compared with nifedipine, amlodipine, verapamil, and diltiazem. Besides, other results suggest that Ki for compound 11 was lower compared with nifedipine, verapamil, and diltiazem. All these data suggest that chalcone derivatives 1 and 11 could act as calcium channel inhibitors; this phenomenon could be translated into changes in blood pressure through a decrease in calcium intracellular levels. These data suggest that chalcone derivatives 1 and 11 could be good therapeutic alternatives to treat heart failure.

Humulus lupulus L.: Evaluation of Phytochemical Profile and Activation of Bitter Taste Receptors to Regulate Appetite and Satiety in Intestinal Secretin Tumor Cell Line (STC-1 Cells).

Inflorescences of the female hop plant (Humulus lupulus L.) contain biologically active compounds, most of which have a bitter taste. Given the rising global obesity rates, there is much increasing interest in bitter taste receptors (TAS2Rs). Intestinal TAS2Rs can have beneficial effects on obesity when activated by bitter agonists. This study aims to investigate the mechanism of action of a hydroalcoholic hop extract in promoting hormone secretion that reduces the sense of hunger at the intestinal level through the interaction with TAS2Rs. The results demonstrate that the hop extract is a rich source of bitter compounds (mainly α-, β-acids) that stimulate the secretion of anorexigenic peptides (glucagon-like peptide 1 [GLP-1], cholecystokinin [CCK]) in a calcium-dependent manner while reducing levels of hunger-related hormones like ghrelin. This effect is mediated through interaction with TAS2Rs, particularly Tas2r138 and Tas2r120, and through the activation of downstream signaling cascades. Knockdown of these receptors using siRNA transfection and inhibition of Trpm5, Plcβ-2, and other calcium channels significantly reduces the hop-induced calcium response as well as GLP-1 and CCK secretion. This study provides a potential application of H. lupulus extract for the formulation of food supplements with satiating activity capable of preventing or combating obesity.

Levofloxacin induces erythrocyte contraction leading to red cell death.

Levofloxacin, a fluoroquinolone, is an extensively used antibiotic effective against both positively and negatively staining bacteria. It works by inhibiting bacterial topoisomerase type II and topoisomerase type IV, resulting in impaired DNA synthesis and bacterial cell death. Eryptosis is another term for apoptotic cell death of erythrocyte marked by cell shrinkage, phosphatidylserine (PS) flipping, and membrane blebbing. The intent of the present research was to look at the eryptotic effect of levofloxacin by exposing erythrocytes to therapeutical doses (7, 14 µM) of levofloxacin for 48 hours. Cell size evaluation, PS subjection to outside, and calcium channel inhibition were carried out to investigate eryptosis. Oxidative stress generated by levofloxacin was measured as a putative mechanism of eryptosis using glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase activities. Similarly, hemolysis measurements demonstrated levofloxacin's cytotoxic effect. Our findings showed that therapeutic doses of levofloxacin can cause a considerable decline in antioxidant enzymes activities, as well as induce cell shrinkage, PS externalization, and hemolysis in erythrocytes. The role of calcium in triggering erythrocyte shrinkage was also confirmed. In conclusion, our findings showed that the indicated levofloxacin doses caused oxidative stress, which leads to erythrocyte death via eryptosis and hemolysis. These findings emphasize the importance of using levofloxacin with caution and the need for additional research to mitigate these side effects.

An L-type calcium channel blocker nimodipine exerts anti-fibrotic effects by attenuating TGF-β1 induced calcium response in an in vitro model of thyroid eye disease

BackgroundThyroid eye disease (TED) is a vision-threatening autoimmune disorder. Orbital tissue fibrosis leading to intractable complications remains a troublesome issue in TED management. Exploration of novel therapeutic targets and agents to ameliorate tissue fibrosis is crucial for TED. Recent work suggests that Ca2+ signaling participates in tissue fibrosis. However, whether an alteration of Ca2+ signaling has a role in fibrogenesis during TED remains unclear. In this study, we aimed to investigate the role of Ca2+ signaling in the fibrogenesis process during TED and the potential therapeutic effects of a highly selective inhibitor of the L-type calcium channel (LTCC), nimodipine, through a TGF-β1 induced in vitro TED model.MethodsPrimary culture of orbital fibroblasts (OFs) were established from orbital adipose connective tissues of patients with TED and healthy control donors. Real-time quantitative polymerase chain reaction (RT-qPCR) and RNA sequencing were used to assess the genes expression associated with LTCC in OFs. Flow cytometry, RT-qPCR, 5-ethynyl-2′-deoxyuridine (EdU) proliferation assay, wound healing assay and Western blot (WB) were used to assess the intracellular Ca2+ response on TGF-β1 stimulation, and to evaluate the potential therapeutic effects of nimodipine in the TGF-β1 induced in vitro TED model. The roles of Ca2+/calmodulin-dependent protein kinase II (CaMKII) and signal transducer and activator of transcription 1 (STAT1) in fibrogenesis during TED were determined by immunohistochemistry, WB, flow cytometry and co-immunoprecipitation assay. Selective inhibitors were used to explore the downstream signaling pathways.ResultsLTCC inhibitor nimodipine blocked the TGF-β1 induced intracellular Ca2+ response and further reduced the expression of alpha-smooth muscle actin (α-SMA), collagen type I alpha 1 (Col1A1) and collagen type I alpha 2 (Col1A2) in OFs. Besides, nimodipine inhibited cell proliferation and migration of OFs. Moreover, our results provided evidence that activation of the CaMKII/STAT1 signaling pathway was involved in fibrogenesis during TED, and nimodipine inhibited the pro-fibrotic functions of OFs by down-regulating the CaMKII/STAT1 signaling pathway.ConclusionsTGF-β1 induces an LTCC-mediated Ca2+ response, followed by activation of CaMKII/STAT1 signaling pathway, which promotes the pro-fibrotic functions of OFs and participates in fibrogenesis during TED. Nimodipine exerts potent anti-fibrotic benefits in vitro by suppressing the CaMKII/STAT1 signaling pathway. Our work deepens our understanding of the fibrogenesis process during TED and provides potential therapeutic targets and alternative candidate for TED.

Vasorelaxant Effect and Blood Pressure Reduction Potential of Pitaya Juice Concentrate (Stenocereus huastecorum) Associated with Calcium Channel Blockade.

Arterial hypertension is a highly prevalent chronic disease worldwide, with several etiologies and treatments that may eventually have side effects or result in patients developing tolerance. There is growing interest in traditional medicine and functional foods to isolate biomolecules that could be useful as coadjuvants for treating several aliments. Pitaya, a desert fruit endemic in Mexico, is a rich source of bioactive molecules (betalains and phenolic compounds). In this work, the vasorelaxation properties of pitaya juice concentrate and fraction one were investigated using aortic and mesenteric rings from rats. The incubation of rings with pitaya juice concentrate or fraction one induced significant vasorelaxation, independent of the endothelium, and showed resistance to potassium channel blockers. This vasorelaxation was associated with the transmembrane influx of extracellular calcium through the vascular smooth muscle cells, with an inhibitory effect on the voltage-dependent calcium channel currents. Also, 400 mg/mL of pitaya juice concentrate in spontaneous hypertensive rats reduced their blood pressure for 48 h. Phytochemical analyses showed that the primary compounds in F1 were glycosidic in nature, and could be a complex mixture of disaccharides, dimeric disaccharides, or even tetrasaccharides. The glycosidic compounds found in F1 primarily contributed to vasodilatation, establishing a voltage-dependent calcium channel inhibition as a possible molecular target.

SKF-96365 Expels Tyrosine Kinase Inhibitor-Treated CML Stem and Progenitor Cells from the HS27A Stromal Cell Niche in a RhoA-Dependent Mechanism.

A major issue in Chronic Myeloid Leukemia (CML) is the persistence of quiescent leukemia stem cells (LSCs) in the hematopoietic niche under tyrosine kinase inhibitor (TKI) treatment. Here, using CFSE sorting, we show that low-proliferating CD34+ cells from CML patients in 3D co-culture hide under HS27A stromal cells during TKI treatment-a behavior less observed in untreated cells. Under the same conditions, Ba/F3p210 cells lose their spontaneous motility. In CML CD34+ and Ba/F3p210 cells, while Rac1 is completely inhibited by TKI, RhoA remains activated but is unable to signal to ROCK. Co-incubation of Ba/F3p210 cells with TKI, SKF-96365 (a calcium channel inhibitor), and EGF restores myosin II activation and amoeboid motility to levels comparable to untreated cells, sustaining the activation of ROCK. In CFSE+ CD34+ cells containing quiescent leukemic stem cells, co-incubation of TKI with SKF-96365 induced the expulsion of these cells from the HS27A niche. This study underscores the role of RhoA in LSC behavior under TKI treatment and suggests that SKF-96365 could remobilize quiescent CML LSCs through reactivation of the RhoA/ROCK pathway.

Total Synthesis of Ganoapplanin Enabled by a Radical Addition/Aldol Reaction Cascade.

The total synthesis of the Ganoderma meroterpenoid ganoapplanin, an inhibitor of T-type voltage-gated calcium channels, is reported. Our synthetic approach is based on the convergent coupling of a readily available aromatic polyketide scaffold with a bicyclic terpenoid fragment. The three contiguous stereocenters of the terpenoid fragment, two of which are quaternary, were constructed by a diastereoselective, titanium-mediated iodolactonization. For the fusion of the two fragments and to simultaneously install the crucial biaryl bond, we devised a highly effective two-component coupling strategy. This event involves an intramolecular 6-exo-trig radical addition of a quinone monoacetal followed by an intermolecular aldol reaction. A strategic late-stage oxidation sequence allowed the selective installation of the remaining oxygen functionalities and the introduction of the characteristic spiro bisacetal structure of ganoapplanin.

Cortical Tagged Synaptic Long-Term Depression in the Anterior Cingulate Cortex of Adult Mice.

The anterior cingulate cortex (ACC) is a key cortical region for pain perception and emotion. Different forms of synaptic plasticity, including long-term potentiation (LTP) and long-term depression (LTD), have been reported in the ACC. Synaptic tagging of LTP plays an important role in hippocampus-related associative memory. In this study, we demonstrate that synaptic tagging of LTD is detected in the ACC of adult male and female mice. This form of tagged LTD requires the activation of metabotropic glutamate receptor subtype 1 (mGluR1). The induction of tagged LTD is time-related with the strongest tagged LTD appearing when the interval between two independent stimuli is 30 min. Inhibitors of mGluR1 blocked the induction of tagged LTD; however, blocking N-methyl-d-aspartate receptors did not affect the induction of tagged LTD. Nimodipine, an inhibitor of L-type voltage-gated calcium channels, also blocked tagged LTD. In an animal model of amputation, we found that tagged LTD was either reduced or completely blocked. Together with our previous report of tagged LTP in the ACC, this study strongly suggests that excitatory synapses in the adult ACC are highly plastic. The biphasic tagging of synaptic transmission provides a new form of heterosynaptic plasticity in the ACC which has functional and pathophysiological significance in phantom pain.

COMPARATIVE ANALYSIS OF MECHANISMS OF ACTION OF PEPTIDE TOXINS, INHIBITORS OF CALCIUM AND SODIUM CHANNELS, UNDER ISCHEMIA/REPERFUSION

Ischemia contributes to many pathological conditions encountered in clinical practice. Besides, subsequent reperfusion may worsen tissue damage, exacerbating injuries caused by ischemia. Shifts in the balance of calcium and sodium ions play a major role in the development of ischemia-reperfusion injury. Inhibitors of calcium and sodium ion channels located on the membrane surface can help to avoid a sharp disturbance in the ion balance. Although such inhibitors reduce cell death, their mechanisms of action differ. The aim of the study is to conduct a comparative analysis of the mechanisms of action of peptide inhibitors of calcium and sodium channels on ischemia-reperfusion damage to epithelial cells. Materials and Methods. Peptide synthesizer was used for toxin synthesis. Chromatography and mass spectrometry were used for quality control. Analysis of cell death, changes in calcium and sodium ion concentrations, and pH levels were performed using fluorescent dyes and a multimodal reader. Results. It was found that peptide inhibitors of calcium and sodium channels reduce apoptosis and necrosis levels in CHO-K1 culture under simulated ischemia/reperfusion. The calcium channel inhibitor reduces cell death by lowering calcium and sodium ion concentrations and maintaining physiological pH levels throughout the reperfusion phase. The sodium channel inhibitor reduces death by lowering calcium and increasing sodium concentrations, and by maintaining an elevated pH throughout the reperfusion phase. Conclusion. Although both calcium and sodium concentrations as well as their mutual influence play an important role in the development of ischemia-reperfusion injury, inhibition of certain channels has different effects on intracellular processes with the same result, namely reduced cell death.

Transcriptome profiling of fast/glycolytic and slow/oxidative muscle fibers in aging and obesity

Aging and obesity pose significant threats to public health and are major contributors to muscle atrophy. The trends in muscle fiber types under these conditions and the transcriptional differences between different muscle fiber types remain unclear. Here, we demonstrate distinct responses of fast/glycolytic fibers and slow/oxidative fibers to aging and obesity. We found that in muscles dominated by oxidative fibers, the proportion of oxidative fibers remains unchanged during aging and obesity. However, in muscles dominated by glycolytic fibers, despite the low content of oxidative fibers, a significant decrease in proportion of oxidative fibers was observed. Consistently, our study uncovered that during aging and obesity, fast/glycolytic fibers specifically increased the expression of genes associated with muscle atrophy and inflammation, including Dkk3, Ccl8, Cxcl10, Cxcl13, Fbxo32, Depp1, and Chac1, while slow/oxidative fibers exhibit elevated expression of antioxidant protein Nqo-1 and downregulation of Tfrc. Additionally, we noted substantial differences in the expression of calcium-related signaling pathways between fast/glycolytic fibers and slow/oxidative fibers in response to aging and obesity. Treatment with a calcium channel inhibitor thapsigargin significantly increased the abundance of oxidative fibers. Our study provides additional evidence to support the transcriptomic differences in muscle fiber types under pathophysiological conditions, thereby establishing a theoretical basis for modulating muscle fiber types in disease treatment.

Intravenous iron therapy results in rapid and sustained rise in myocardial iron content through a novel pathway.

Intravenous iron therapies contain iron-carbohydrate complexes, designed to ensure iron becomes bioavailable via the intermediary of spleen and liver reticuloendothelial macrophages. How other tissues obtain and handle this iron remains unknown. This study addresses this question in the context of the heart. A prospective observational study was conducted in 12 patients receiving ferric carboxymaltose (FCM) for iron deficiency. Myocardial, spleen, and liver magnetic resonance relaxation times and plasma iron markers were collected longitudinally. To examine the handling of iron taken up by the myocardium, intracellular labile iron pool (LIP) was imaged in FCM-treated mice and cells. In patients, myocardial relaxation time T1 dropped maximally 3 h post-FCM, remaining low 42 days later, while splenic T1 dropped maximally at 14 days, recovering by 42 days. In plasma, non-transferrin-bound iron (NTBI) peaked at 3 h, while ferritin peaked at 14 days. Changes in liver T1 diverged among patients. In mice, myocardial LIP rose 1 h and remained elevated 42 days after FCM. In cardiomyocytes, FCM exposure raised LIP rapidly. This was prevented by inhibitors of NTBI transporters T-type and L-type calcium channels and divalent metal transporter 1. Intravenous iron therapy with FCM delivers iron to the myocardium rapidly through NTBI transporters, independently of reticuloendothelial macrophages. This iron remains labile for weeks, reflecting the myocardium's limited iron storage capacity. These findings challenge current notions of how the heart obtains iron from these therapies and highlight the potential for long-term dosing to cause cumulative iron build-up in the heart.

H2SIncreases Blood Pressure via Activation of L-Type Calcium Channels with Mediation by HS•Generated from Reactions with Oxyhemoglobin.

Although the gasotransmitter hydrogen sulfide (H2S) is well known for its vasodilatory effects, H2S also exhibits vasoconstricting properties. Herein, it is demonstrated that administration of H2S as intravenous sodium sulfide (Na2S) increased blood pressure in sheep and rats, and this effect persisted after H2S has disappeared from the blood. Inhibition of the L-type calcium channel (LTCC) diminished the hypertensive effects. Incubation of Na2S with whole blood, red blood cells, methemoglobin, or oxyhemoglobin produced a hypertensive product of H2S, which is not hydrogen thioperoxide, metHb-SH- complexes, per-/poly- sulfides, or thiolsulfate, but rather a labile intermediate. One-electron oxidation of H2S by oxyhemoglobin generated its redox cousin, sulfhydryl radical (HS•). Consistent with the role of HS• as the hypertensive intermediate, scavenging HS• inhibited Na2S-induced vasoconstriction and activation of LTCCs. In conclusion, H2S causes vasoconstriction that is dependent on the activation of LTCCs and generation of HS• by oxyhemoglobin.