Isolation and structural identification of a potassium ion channel Kv4.1 inhibitor SsTx-P2 from centipede venom / 浙江大学学报·医学版

OBJECTIVES@#To isolate potassium ion channel Kv4.1 inhibitor from centipede venom, and to determine its primary and spatial structure.@*METHODS@#Ion-exchange chromatography and reversed-phase high-performance liquid chromatography were performed to separate and purify peptide components of centipede venom, and their inhibiting effect on Kv4.1 channel was determined by whole-cell patch clamp recording. The molecular weight of isolated peptide Kv4.1 channel inhibitor was identified with MALDI-TOF, its primary sequence was determined by Edman degradation sequencing and two-dimensional mass spectrometry, its patial structure was established based on iterative thread assembly refinement online analysis.@*RESULTS@#A peptide SsTx-P2 was separated from centipede venom with the molecular weight of 6122.8, and its primary sequence consists of 53 amino acid residues, showed as NH2-ELTWDFVRTCCKLFPDKSECTKACATEFTGGDESRLKDVWPRKLRSGDSRLKD-OH. Peptide SsTx-P2 potently inhibited the current of Kv4.1 channel transiently transfected in HEK293 cell, with 1.0 μmol/L SsTx-P2 suppressing 95% current of Kv4.1 channel. Its spatial structure showed that SsTx-P2 shared a conserved helical structure.@*CONCLUSIONS@#The study has isolated a novel peptide SsTx-P2 from centipede venom, which can potently inhibit the potassium ion channel Kv4.1, and its spatial structure displays a certain degree of conservation.

Drofenine as a Kv2.1 inhibitor alleviated AD-like pathology in mice through A β/Kv2.1/microglial NLRP3/neuronal tau axis / 中国药理学与毒理学杂志

OBJECTIVE Alzheimer disease(AD)is a neurodegenerative disease with clinical hallmarks of pro-gressive cognitive impairment.Synergistic effects of Aβ-tau cascade reaction are tightly implicated in AD patholo-gy,and microglial NLRP3 inflammasome activation drives neuronal tauopathy through microglia and neurons cross-talk.However,the underlying mechanism of how Aβ medi-ates NLRP3 inflammasome remains unclear.Shab related potassium channel member 1(Kv2.1)as a voltage gated po-tassium channel widely distributed in the central nervous system and plays an important role in regulating the out-ward potassium flow in neurons and glial cells.In current work,we aimed to explore the underlying mechanism of Kv2.1 in regulating Aβ/NLRP3 inflammasome/tau axis by using a determined Kv2.1 inhibitor drofenine(Dfe).METHODS Cell-based assays including Western blot-ting and immunofluorescence staining against primary microglia or neurons were carried out to expound the role of Kv2.1 channel in NLRP3 inflammasome activa-tion and subsequent neuronal tau hyperphosphorylation.For animal studies,new object recognition,Y-maze and Morris water maze were performed to evaluate the ame-lioration of Kv2.1 inhibition through either Kv2.1 inhibitor Dfe treatment or adeno-associated virus AAV-ePHP-si-Kv2.1injectionon5×FADADmodel mice.Assays of histol-ogy and immunostaining of tissue sections and Western blotting of brain tissues were performed to verify the con-clusion of cellular assays.RESULTS We reported that oligomeric Aβ(o-Aβ)bound to microglial Kv2.1 and pro-moted Kv2.1-dependent potassium leakage to activate NLRP3 inflammasome through JNK/NF-κB pathway sub-sequently resulting in neuronal tauopathy.Treatment of either Kv2.1 inhibitor Dfe or AAV-ePHP-si-Kv2.1 for brain-specific Kv2.1 knockdown deprived o-A β of its capability in inducing microglial NLRP3 inflammasome activation and neuronal tau hyperphosphorylation,while improved the cognitive impairment of 5×FAD AD model mice.CONCLUSION Our results have highly addressed that Kv2.1 channel is required for o-Aβ driving NLRP3 inflammasome activation and neuronal tauopathy in AD model mice and highlighted that Kv2.1 inhibition is a prom-ising therapeutical strategy for AD and Dfe as a Kv2.1 inhibitor shows potential in the treatment of this disease.

AGEs in DRG Participates in Gastric Hypersensitivity by Regulating Expression of Kv4.2 in Diabetes Mellitus Rat Model / 胃肠病学

Background: Diabetic gastroparesis (DGP) is one of the most common complications of diabetes mellitus (DM), and its main symptoms include upper abdominal pain, nausea, vomiting, abdominal distension, etc. Gastric hypersensitivity is the main pathogenesis of DGP. Advanced glycation end products (AGEs) is the initiating factor of chronic complications of DM, and its relationship with gastric hypersensitivity has not yet been clear. Kv4.2 channel plays an important role in regulating visceral sensation. Subunit inactivation of Kv4.2 can reduce potassium current, enhance pain sensation, and increase gastric sensitivity. Aims: To investigate the mechanism of AGEs participating in gastric hypersensitivity by regulating the expression or activity of Kv4.2 channel in DM rat model. Methods: Fifty⁃four rats were randomly divided into control group, DM group and DM+AG group. Streptozocin (STZ) was intraperitoneally injected to induce DM rat model. Blood glucose, body weight, gastric sensitivity and gastric emptying rate were monitored. Western blotting and ELISA were used to detect CML content in stomach tissue and serum, respectively. The expression of RAGE and its co⁃expression with Kv4.2 in dorsal root ganglia (DRG) neurons were detected by immunofluorescence. Western blotting was used to detect RAGE expression and phosphorylation levels of ERK1/2 and Kv4.2 in DRG neurons. Results: Compared with control group, gastric sensitivity was significantly increased in DM group (P<0.01), gastric emptying rate was significantly decreased (P<0.05), AGEs marker CML content in serum and gastric tissue were significantly increased (P<0.05), co ⁃ expression rate of RAGE and Kv4.2 in DRG neurons was significantly increased (P<0.01), and phosphorylation levels of ERK1/2 and Kv4.2 were up⁃regulated (P<0.05). After intervention with AG, above⁃mentioned indices were significantly ameliorated (P<0.05). Conclusions: AGEs is an upstream factor leading to gastric hypersensitivity in DM rat model. AGEs increases the excitability of DRG neurons by inhibiting Kv4.2 channel, leading to gastric hypersensitivity. RAGE and ERK1/2 signal may be involved in the above process.

KCNH2 mutation c.3099_3112del causes congenital long QT syndrome type 2 with gender differences

Abstract Introduction: Long QT Syndrome (LQTS) is an inherited disease with an abnormal electrical conduction system in the heart that can cause sudden death as a result of QT prolongation. LQT2 is the second most common subtype of LQTS caused by loss of function mutations in the potassium voltage-gated channel subfamily H member 2 (KCNH2) gene. Although more than 900 mutations are associated with the LQTS, many of these mutations are not validated or characterized. Methods and results: Sequencing analyses of genomic DNA of a family with LQT2 identified a putative mutation. i.e., KCNH2(NM_000238.3): c.3099_3112del, in KCNH2 gene which appeared to be a definite pathogenic mutation. The family pedigree information showed a gender difference in clinical features and T-wave morphology between male and female patients. The female with mutation exhibited recurring ventricular arrhythmia and syncope, while two male carriers did not show any symptoms. In addition, T-wave in females was much flatter than in males. The female proband showed a positive reaction to the lidocaine test. Lidocaine injection almost completely blocked ventricular arrhythmia and shortened the QT interval by ≥30 ms. Treatment with propranolol, mexiletine, and implantation of cardioverter-defibrillators prevented the sustained ventricular tachycardia, ventricular fibrillation, and syncope, as assessed by a 3-year follow-up evaluation. Conclusions: A putative mutation c.3099_3112del in the KCNH2 gene causes LQT2 syndrome, and the pathogenic mutation mainly causes symptoms in female progeny.

Protein Kinase C Controls the Excitability of Cortical Pyramidal Neurons by Regulating Kv2.2 Channel Activity / 神经科学通报·英文版

The family of voltage-gated potassium Kv2 channels consists of the Kv2.1 and Kv2.2 subtypes. Kv2.1 is constitutively highly phosphorylated in neurons and its function relies on its phosphorylation state. Whether the function of Kv2.2 is also dependent on its phosphorylation state remains unknown. Here, we investigated whether Kv2.2 channels can be phosphorylated by protein kinase C (PKC) and examined the effects of PKC-induced phosphorylation on their activity and function. Activation of PKC inhibited Kv2.2 currents and altered their steady-state activation in HEK293 cells. Point mutations and specific antibodies against phosphorylated S481 or S488 demonstrated the importance of these residues for the PKC-dependent modulation of Kv2.2. In layer II pyramidal neurons in cortical slices, activation of PKC similarly regulated native Kv2.2 channels and simultaneously reduced the frequency of action potentials. In conclusion, this study provides the first evidence to our knowledge that PKC-induced phosphorylation of the Kv2.2 channel controls the excitability of cortical pyramidal neurons.

Analgesic effects of aspirin combined with kv7 channel openers / 中国药理学通报

Aim To provide scientific evidence for clinical drug combination by exploring the analgesic effect of aspirin combined with Kv7 channel openers, retigabine and flupirtine. Methods The mice were randomly divided into control group, aspirin group, flupirtine group, retigabine group, aspirin + flupirtine group and aspirin + retigabine group. To assess the antinociceptive effects of each group, the acetic acid-induced abdominal constriction test and the hot-plate test were used. Results In the acetic acid-induced abdominal constriction test, compared to aspirin group, the amount of abdominal constriction in aspirin + flupirtine group was significantly reduced (P <0.01). The latent period of abdominal constriction in aspirin + retigabine group was significantly prolonged ( P < 0. 01) and the number of abdominal constriction was significantly reduced (P < 0. 01). In the hot-plate test, compared to aspirin group, the increment percentage of latent period in aspirin + flupirtine group and aspirin + retigabine group showed an increased trend. Among them, the increment percentage of latent period 30 and 60 minutes after injections in aspirin + retigabine group had a significant difference from that in aspirin group (P <0. 05). Conclusion Kv7 channel openers, retigabine and flupirtine, can enhance the analgesic effect of aspirin.

Jingzhaotoxin-X, a gating modifier of Kv4.2 and Kv4. 3 potassium channels purified from the venom of the Chinese tarantula Chilobrachys jingzhao

The tarantula Chilobrachys jingzhao is one of the largest venomous spiders in China. In previous studies, we purified and characterized at least eight peptides from C. jingzhao venom. In this report, we describe the purification and characterization of Jingzhaotoxin-X (JZTX-X), which selectively blocks Kv4.2 and Kv4.3 potassium channels. Methods: JZTX-X was purified using a combination of cation-exchange HPLC and reverse-phase HPLC. The amino-acid sequence was determined by automated Edman degradation and confirmed by mass spectrometry (MS). Voltage-gated ion channel currents were recorded in HEK293t cells transiently transfected with a variety of ion channel constructs. In addition, the hyperalgesic activity of JZTX-X and the toxin´s effect on motor function were assessed in mice. Results: JZTX-X contained 31 amino acids, with six cysteine residues that formed three disulfide bonds within an inhibitory cysteine knot (ICK) topology. In whole-cell voltage-clamp experiments, JZTX-X inhibited Kv4.2 and Kv4.3 potassium channels in a concentration- and voltage-dependent manner, without affecting other ion channels (Kv1.1, 1.2, 1.3, 2.1, delayed rectifier potassium channels, high- and low-voltage-activated Ca2+ channels, and voltage-gated sodium channels Nav1.5 and 1.7). JZTX-X also shifted the voltage-dependent channel activation to more depolarized potentials, whereas extreme depolarization caused reversible toxin binding to Kv4.2 channels. JZTX-X shifted the Kv4.2 and Kv4.3 activities towards a resting state, since at the resting potential the toxin completely inhibited the channels, even in the absence of an applied physical stimulus. Intrathecal or intraplantar injection of JZTX-X caused a long-lasting decrease in the mechanical nociceptive threshold (hyperalgesia) but had no effect on motor function as assessed in the rotarod test. Conclusions: JZTX-X selectively suppresses Kv4.2 and Kv4.3 potassium channel activity in a concentration- and voltage-dependent manner and causes long-lasting mechanical hyperalgesia.(AU)

Assessment Of Set Up Errors And Determination Of Planning Target Volume Margins In Image Guided Radiotherapy For Cervical Cancer Patients Treated In Supine Position

BACKGROUND:Proper positioning of a patient during radiotherapy treatment delivery is crucial for successful implementation of a treatment plan ensuring maximum dose to the target while minimising the dose to the normal tissues. The purpose of this study is to assess the set up errors and to determine the optimal Clinical Target Volume (CTV) to Planning Target Volume (PTV) margins for Cervical Carcinoma patients treated in supine position by Image guided Radiotherapy.METHODS AND MATERIALS: 219 kVCBCTimages were acquired for 10 cervical cancer patients treated with Conformal External Beam Radiotherapy using Image Guidance. Daily set-up errors along the three translational directions were analysed, evaluated for systematic and random errors and optimal CTV-PTVmargin determined.RESULTS:Corresponding CTV-PTVmargins in the X, Yand Z directions were 0.7cm, 1.7cm and 0.4cm respectively.CONCLUSION:IGRTis imperative for ensuring adequate target volume coverage and eliminating geographic miss in IMRTtreatment

Effects of 3,3′,4,4′,5-pentachlorobiphenyl on human Kv1.3 and Kv1.5 channels

Among the environmental chemicals that may be able to disrupt the endocrine systems of animals and humans are polychlorinated biphenyls (PCBs), a chemical class of considerable concern. PCB consists of two six-carbon rings linked by a single carbon bond, and theoretically, 209 congeners can form, depending on the number of chlorines and their location on the biphenyl rings. Furthermore, 3,3′,4,4′,5-pentachlorobiphenyl (PCB126) exposure also increases nitric oxide production and nuclear factor kappa-light-chain-enhancer of activated B cells binding activity in chondrocytes, thus contributing as an initiator of chondrocyte apoptosis and resulting in thymic atrophy and immunosuppression. This study identified whether cardiac and immune abnormalities from PCB126 were caused by the Kv1.3 and Kv1.5 channels. PCB126 did not affect either the steady-state current or peak current of the Kv1.3 and Kv1.5 channels. However, PCB126 right-shifted the steady-state activation curves of human Kv1.3 channels. These results suggest that PCBs can affect the heart in a way that does not block voltage-dependent potassium channels including Kv1.3 and Kv1.5 directly.

Scorpion toxins targeting Kv1 3 channels: insights into immunosuppression

Scorpion venoms are natural sources of molecules that have, in addition to their toxic function, potential therapeutic applications. In this source the neurotoxins can be found especially those that act on potassium channels. Potassium channels are responsible for maintaining the membrane potential in the excitable cells, especially the voltage-dependent potassium channels (Kv), including Kv1.3 channels. These channels (Kv1.3) are expressed by various types of tissues and cells, being part of several physiological processes. However, the major studies of Kv1.3 are performed on T cells due its importance on autoimmune diseases. Scorpion toxins capable of acting on potassium channels (KTx), mainly on Kv1.3 channels, have gained a prominent role for their possible ability to control inflammatory autoimmune diseases. Some of these toxins have already left bench trials and are being evaluated in clinical trials, presenting great therapeutic potential. Thus, scorpion toxins are important natural molecules that should not be overlooked in the treatment of autoimmune and other diseases.(AU)

Phantom study of the influence of CareDose 4D and Care kV on CT pulmonary ground glass nodule with respect to image quality and radiation dose / 中华放射医学与防护杂志

Objective To investigate the effect of CareDose 4D combined with Care kV on CT pulmonary ground glass nodule ( GGN) with respect to quality and radiation dose. Methods The thoracic model containing 6 GGN was performed by using 7 low-dose schemes. The CareDose 4D + Care kV was adopted in scheme 1. In schemes 2, 3 and 4, the tube voltage was 120 kV, and the tube current 30, 20 and 10 mAs respectively. In schemes 5, 6 and 7, the tube voltage was 100 kV, and the tube current was 30, 20 and 10 mAs, respectively. The image quality [ CT value, contrast noise ratio ( CNR) , noise value (SD) and subjective score] and effective dose (E) were compared. Results There was no statistically significant difference in CT value of GGN among different schemes (P>0. 05). The SD of scheme 1 was higher than those of schemes 2, 3 and 5, but lower than those f scheme 7, while the CNR of scheme 1 was lower than those of schemes 2, 3 and 5, but higher than that of scheme 7 ( t=13. 020, 9. 560, 8. 120,-5. 720, -7. 849, -5. 192, -4. 130, 1. 361,P<0. 05). SD and CNR of scheme 1 were not significantly different from those of scheme 4 and 6 ( P>0. 05) . The subjective scores of each GGN of schemes 1, 2, 3, 5 and 6 was over 3 points, but and the subjective scores of one GGN of each of schemes 4 and 7 were below 3 points. The value E of the scheme 1 was reduced by 63. 0％, 44. 4％, 38. 8％, and 9. 1％, compared with the schemes 2, 3, 5 and 6, respectively. Conclusions CareDose 4D combined with Care kV in low-dose lung CT scan can ensure the image quality of GGN and reduce the radiation dose effectively.

Potassium Channels: A Potential Therapeutic Target for Parkinson's Disease / 神经科学通报·英文版

The pathogenesis of the second major neurodegenerative disorder, Parkinson's disease (PD), is closely associated with the dysfunction of potassium (K) channels. Therefore, PD is also considered to be an ion channel disease or neuronal channelopathy. Mounting evidence has shown that K channels play crucial roles in the regulations of neurotransmitter release, neuronal excitability, and cell volume. Inhibition of K channels enhances the spontaneous firing frequency of nigral dopamine (DA) neurons, induces a transition from tonic firing to burst discharge, and promotes the release of DA in the striatum. Recently, three K channels have been identified to protect DA neurons and to improve the motor and non-motor symptoms in PD animal models: small conductance (SK) channels, A-type K channels, and K7/KCNQ channels. In this review, we summarize the physiological and pharmacological effects of the three K channels. We also describe in detail the laboratory investigations regarding K channels as a potential therapeutic target for PD.

The Role of Serotonin in Ventricular Repolarization in Pregnant Mice

PURPOSE: The mechanisms underlying repolarization abnormalities during pregnancy are not fully understood. Although maternal serotonin (5-hydroxytryptamine, 5-HT) production is an important determinant for normal fetal development in mice, its role in mothers remains unclear. We evaluated the role of serotonin in ventricular repolarization in mice hearts via 5Htr3 receptor (Htr3a) and investigated the mechanism of QT-prolongation during pregnancy. MATERIALS AND METHODS: We measured current amplitudes and the expression levels of voltage-gated K⁺ (Kv) channels in freshly-isolated left ventricular myocytes from wild-type non-pregnant (WT-NP), late-pregnant (WT-LP), and non-pregnant Htr3a homozygous knockout mice (Htr3a(−/−)-NP). RESULTS: During pregnancy, serotonin and tryptophan hydroxylase 1, a rate-limiting enzyme for the synthesis of serotonin, were markedly increased in hearts and serum. Serotonin increased Kv current densities concomitant with the shortening of the QT interval in WT-NP mice, but not in WT-LP and Htr3a(−/−)-NP mice. Ondansetron, an Htr3 antagonist, decreased Kv currents in WT-LP mice, but not in WT-NP mice. Kv4.3 directly interacted with Htr3a, and this binding was facilitated by serotonin. Serotonin increased the trafficking of Kv4.3 channels to the cellular membrane in WT-NP. CONCLUSION: Serotonin increases repolarizing currents by augmenting Kv currents. Elevated serotonin levels during pregnancy counterbalance pregnancy-related QT prolongation by facilitating Htr3-mediated Kv currents.

The Effects of 4-Hydroxybenzoic Acid Identified from Bamboo (Dendrocalamus asper) Shoots on Kv1.4 Channel

Background: Bamboo shoot has been used as a treatment for epilepsy in traditional Chinese medicine for generations to treat neuronal disorders such as convulsive, dizziness and headaches. 4-hydroxybenzoic acid (4-hba) is a non-flavonoid phenol found abundantly in Dendrocalamus asper shoots (bamboo), fruits (strawberries and apples) and flowers. Kv1.4 is a rapidly inactivating Shaker-related member of the voltage-gated potassium channels with two inactivation mechanisms; the fast N-type and slow C-type. It plays vital roles in repolarisation, hyperpolarisation and signaling the restoration of resting membrane potential through the regulation of the movement of K+ across the cellular membrane. Methods: Chemical compounds from Dendrocalamus asper bamboo shoots were purified and identified as major palmitic acids mixed with other minor fatty acids, palmitic acid, 4-hydroxybenzaldehyde, lauric acid, 4-hydroxybenzoic acid and cholest-4-ene-3-one. The response of synthetic 4-hydroxybenzoic acid was tested on Kv1.4 potassium channel which was injected into viable oocytes that was extracted from Xenopus laevis. The current were detected by the two-microelectrode voltage clamp, holding potential starting from −80 mV with 20 mV stepup until +80 mV. Readings of treatments with 0.1% DMSO, 4-hba concentrations and K channel blockers were taken at +60 mV. The ratio of tail/peak amplitude is the index of the activity of the Kv1.4 channels with n ≥ 6 (number of oocytes tested). The decreases of the ratios of five different concentrations (1 μM, 10 μM, 100 μM, 1 mM and 2.5 mM) were compared with 0.1% DMSO as the control. Results: All concentration showed statistically significant results with P < 0.05 except for 100 μM. The normalised current of the 4-hba concentrations were compared with potassium channel blockers (TEA and 4-AP) and all groups showed statistically significant results. This study also showed that time taken for each concentration to affect Kv1.4 does not play any significant roles. Conclusion: 4-hydroxybenzoic acid was found to be able to enhance the inactivation of Kv1.4 by lowering the membrane potential so that the abnormal neuronal firing can be inhibited. With IC50 slightly higher than 10 μM, increasing concentrations (100 μM, 1 mM and 2.5 mM) had shown to exhibit toxicity effects. The best concentration from this study is 10 μM with Hill slope of 0.1799.

Antidepressant drug paroxetine blocks the open pore of Kv3.1 potassium channel

In patients with epilepsy, depression is a common comorbidity but difficult to be treated because many antidepressants cause pro-convulsive effects. Thus, it is important to identify the risk of seizures associated with antidepressants. To determine whether paroxetine, a very potent selective serotonin reuptake inhibitor (SSRI), interacts with ion channels that modulate neuronal excitability, we examined the effects of paroxetine on Kv3.1 potassium channels, which contribute to highfrequency firing of interneurons, using the whole-cell patch-clamp technique. Kv3.1 channels were cloned from rat neurons and expressed in Chinese hamster ovary cells. Paroxetine reversibly reduced the amplitude of Kv3.1 current, with an IC₅₀ value of 9.43 µM and a Hill coefficient of 1.43, and also accelerated the decay of Kv3.1 current. The paroxetine-induced inhibition of Kv3.1 channels was voltage-dependent even when the channels were fully open. The binding (k₊₁) and unbinding (k₋₁) rate constants for the paroxetine effect were 4.5 µM⁻¹s⁻¹ and 35.8 s⁻¹, respectively, yielding a calculated K(D) value of 7.9 µM. The analyses of Kv3.1 tail current indicated that paroxetine did not affect ion selectivity and slowed its deactivation time course, resulting in a tail crossover phenomenon. Paroxetine inhibited Kv3.1 channels in a usedependent manner. Taken together, these results suggest that paroxetine blocks the open state of Kv3.1 channels. Given the role of Kv3.1 in fast spiking of interneurons, our data imply that the blockade of Kv3.1 by paroxetine might elevate epileptic activity of neural networks by interfering with repetitive firing of inhibitory neurons.

The clinical value of anteroposterior and lateral scout image combined with Care Dose 4D and Care kV in reducing radiation dose of chest CT scanning / 中华放射医学与防护杂志

Objective To investigate the feasibility and clinical value of anteroposterior and lateral scout scan combined with Care Dose 4D and Care kV in chest CT scan.Methods A total of 60 patients of clinical diagnosis with lung tumor were enrolled.Those patients were randomly divided into test group and control group.Control group underwent a scan protocol with lateral scout scan combined with Care Dose 4D and Care kV,while anteroposterior and lateral scout scan combined with Care Dose 4D and Care kV were performed in test group.The signal-to-noise ration (SNR),contrast-to-noise ratio (CNR),and overall image quality of two groups of images and diseased tissues were analyzed and evaluated by two high-grade radiologists using double-blind method.Effective doses (E) were also calculated.Results All the 60 patients had successfully completed the chest CT scans.Test group overall image quality (4.57 ± 0.45) and control group overall image quality (4.73 ± 0.45) had no statistically significant difference (P ＞ 0.05).The control group image SNR,CNR and diseased tissue SNR,CNR compared with test group had no statistical significance difference (P ＞ 0.05).The difference of the volume CT dose index (CTDIvol),dose-length product (DLP) and effective dose (E) of test group and control group was statistically significant (t =8.514,8.464,8.464,P ＜ 0.001).Compared with control group,the effective dose of test group decreased by 33.3％.Conclusions Compared with lateral scout scan,the technology of anteroposterior and lateral scout scan combined with Care Dose 4D and Care kV can decrease radiation dose without reducing the image quality.This technology can therefore be considered as a regular imaging modality for chest CT scan.

Antagonization of eplerenone on proliferation of cardiac fibroblasts induced by co-cultured Treg cells based on inhibition of Kv1.3 channel of Tregs / 中国药理学通报

Aim To establish a co-incubation system in cardiac fibroblasts of SD neonatal rats and spleen CD4+ CD25 + regulatory T lymphocytes (Tregs) of normal adult SD rats,and to investigate the effects of eplerenone(EPL) on the interaction of two cells and the relationship with the Kvl.3 channel on Tregs cell membrane.Methods The spleen Tregs of normal adult SD rats were sorted by immunomagnetic bead sorting,and the myocardial fibroblasts of SD rats were isolated by differential adherence method.The experiment was conducted in the following groups:CFs,CFs + Tregs,CFs + Tregs + EPL,Tregs.The proliferation of CFs was detected by CCK-8 method.The expression levels of type Ⅰ collagen,type m collagen and matrix metalloproteinase 2 (MMP-2) secreted by CFs were detected by ELISA.The mRNA expression levels of Kv1.3,KCa3.1 on Tregs cell membrane and intracellular CRAC channel were detected by RT-qPCR technique.Tregs cell membrane Kvl.3 channel protein expression levels were determined by In-Cell Western blot.Results After 48 h incubation of the co-culture system,the cell proliferation was stable.CFs proliferation was marked(P ＜0.01),which could be inhibited by EPL(P ＜0.01).The type Ⅰ,type Ⅲ collagen and MMP-2 secreted by CFs increased (P ＜ 0.01).The expression levels of Kv1.3,KCa3.1 and CRAC channel mRNA in Tregs increased by 6.95,1.99 and 1.53 fold (CFs + Tregs vs Tregs,P ＜0.01),EPL decreased the mRNA level of each channel (CFs +Tregs + EPLvs CFs + Tregs,P＜0.01),and the decrease of Kv1.3 channel was the most significant (P ＜ 0.01).The Kv1.3 channel protein of Tregs increased by 67.9％ (CFs + Tregs vs Tregs,P ＜0.01),which could be inhibited by EPL(P ＜ 0.01).Conclusions Tregs cultured with CFs after 48 h can significantly promote the proliferation of CFs,and EPL can down-regulate the Kv1.3 channel expression on the Tregs membrane and inhibit the activation/proliferation of Tregs,indirectly inhibiting myocardial fibrosis.

Ondansetron Inhibits Voltage-Gated K⁺ Current of Ventricular Myocytes from Pregnant Mouse

BACKGROUND: The Htr3a antagonist, ondansetron, has been reported to prolong the QT interval and induce Torsades de pointes in the treatment of postoperative nausea and vomiting. To explore the mechanisms underlying these findings, we examined the effects of ondansetron on the mouse cardiac voltage-gated K⁺ (Kv) channel. METHODS AND RESULTS: Ondansetron increased QT intervals in late pregnant (LP) mice. We measured the Kv channels in freshly isolated left ventricular (LV) myocytes from non-pregnant (NP) and late pregnant (LP) mice, using patch-clamp electrophysiology. Ondansetron blocked Kv current at a dose of 50 µM, and reduced the amplitude of peak current densities in a dose-dependent manner (0, 1, 5, 50 µM), in LP but not in NP mice. In contrast, serotonin and the Htr3 agonist, m-CPBG, increased Kv current densities in NP, but not in LP mice. Interestingly, during pregnancy, serum serotonin levels were markedly increased, suggesting the saturation of the effect of serotonin. Immunostaning data showed that Kv4.3 protein and Htr3a co-localize at the membrane and t-tubule of cardiomyocytes. Moreover, Kv4.3 membrane trafficking was enhanced in response to Htr3a-mediated serotonin stimulation in NP, but not in LP mice. Membrane analysis showed that serotonin enhances Kv4.3 membrane trafficking in NP, but not LP mice. CONCLUSION: Ondansetron reduced Kv current densities, and reduced the Kv4.3 membrane trafficking in LP mouse ventricular cardiomyocytes. This data suggests that QT prolongation by ondansetron is mediated by the reduction of Kv current densities and Kv4.3 membrane trafficking.

Kv1.3 channel current changes in neutrophilic asthma and eosinophilic asthma / 国际儿科学杂志

Objective Allergic asthma is a chronic inflammatory disease of the airways.T lymphocytes play important roles in the pathogenesis of asthma.The voltage-gated Kvl.3 potassium channel may be a key factor in the activation of T lymphocytes.This research aims to detect the function of Kvl.3 channel in the neutrophlial asthma(NA) model and eosinophilic asthma(EA) model.Methods A total of 24 mice were randomly assigned into three groups:control,neutrophilic asthma model and eosinophilic asthma group.Neutrophilic asthma model was established with ovalbumin (OVA)and lipopolysaccharide(LPS);eosinophilic asthma was established with OVA and Al(OH)3;airway responsiveness of mice in each group was measured with a noninvasive pulmonary function instrument;lung inflammation changes were observed by pathological HE staining;IL-17A and IL-4 cytokines levels in bronchoalveolar lavage fluid were evaluated by ELISA;Kvl.3 channel protein level in lung was evaluated by western blot;the change of current density in CD4 +.T lymphocytes were tested by whole-cell patch clamp technique.Results Levels of IL-17A and IL-4 in bronchoalveolar lavage fluid increased in both NA and EA model (P ＜ 0.05).Compare with EA model,the IL-17A level was significantly higer in NA model,while the IL-4 level was significantly lower.In NA and EA model,kv1.3 protein expression in lung tissue was significantly higher than that in the control group(P ＜ 0.05),and kv1.3 protein expression in NA model was significantly higer than that in the EA model (P ＜ 0.05).Current intensity and current density of kv1.3 channel increased in both NA and EA model.While the current intensity and current density of kv1.3 channel were significantly higher in NA model than that in EA model.Conclusion Kv1.3 protein level,Kv1.3 channel current intensity and kv1.3 channel current density increased in both NA and EA model,especially in NA group,providing a new way for treatment of bronchial asthma.

Effect of beraprost sodium on HPH rats and expression of oxygen-sensitive Kv channels in pulmonary artery smooth muscle / 西安交通大学学报(医学版)

Objective To explore the effect of beraprost sodium (BPS) on hypoxia-induced pulmonary artery hypertension (HPH) in rats and the expression of oxygen-sensitive Kv channels in pulmonary artery smooth muscle (PASM).Methods The HPH model of rats was established by exposing rats to low-pressure and low-oxygen cabin which was auto-modulated for 8h every day.Rats in the BPS group were given an intragastric administration of BPS [300 μg/(kg · d)],while those in the control group and HPH group were given an intragastric administration of 3 ml/kg of 0.9％ saline.After 4 weeks,the mean pulmonary artery pressure (mPAP) was measured and right heart ventricle hypertrophy index (RVHI) was calculated;pulmonary artery remodeling was evaluated by HE staining;the expressions of Kv 1.2,Kv 1.5 and Kv2.1 in the pulmonary artery were detected by Real-time PCR and Western blot.Results The HPH model was successfully established in rats exposed to chronic hypoxia for 4 weeks.Compared with those in HPH group,mPAP,RVHI and pulmonary artery remodeling were decreased in BPS group [mPAP:(13.48±2.18)mmHg vs.(23.87±2.23)mmHg vs.(17.09±1.20)mmHg;RVHI:0.28±0.02 vs.0.46±0.03 vs.0.36±0.04;％ area of medial smooth muscle:35.72±6.58 vs.68.52±5.64 vs.46.58±8.43;P＜0.05],and the mRNA and protein expressions of Kv 1.2,Kv 1.5 and Kv 2.1 were increased (relative protein expression level:Kv1.2,0.78±0.10 vs.0.15±0.03 vs.0.57±0.13;Kv1.5,0.61±0.10 vs.0.31±0.05 vs.0.59±0.13;Kv2.1,0.29±0.05 vs.0.10±0.02 vs.0.28±0.07;P＜0.05).Conclusion BPS can improve pulmonary arterial hypertension induced by hypoxia,and upregulate the decreased mRNA and protein expressions of Kv 1.2,Kv 1.5 and Kv 2.1 in pulmonary artery.