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Objective:Trigeminal neuralgia(TN)is a common neuropathic pain.Voltage-gated potassium channel(Kv)has been confirmed to be involved in the occurrence and development of TN,but the specific mechanism is still unclear.MicroRNA may be involved in neuropathic pain by regulating the expression of Kv channels and neuronal excitability in trigeminal ganglion(TG).This study aims to explore the relationship between Kv1.1 and miR-21-5p in TG with a TN model,evaluate whether miR-21-5p has a regulatory effect on Kv1.1,and to provide a new target and experimental basis for the treatment of TN. Methods:A total of 48 SD rats were randomly divided into 6 groups:1)a sham group(n= 12),the rats were only sutured at the surgical incision without nerve ligation;2)a sham+ agomir NC group(n=6),the sham rats were microinjected with agomir NC through stereotactic brain injection in the surgical side of TG;3)a sham+miR-21-5p agomir group(n=6),the sham rats were microinjected with miR-21-5p agomir via stereotactic brain injection in the surgical side of TG;4)a TN group(n=12),a TN rat model was constructed using the chronic constriction injury of the distal infraorbital nerve(dIoN-CCI)method with chromium intestinal thread;5)a TN+antagonist NC group(n=6),TN rats were microinjected with antagonist NC through stereotactic brain injection method in the surgical side of TG;6)a TN+miR-21-5p antagonist group(n=6),TN rats were microinjected with miR-21-5p antagonist through stereotactic brain injection in the surgical side of TG.The change of mechanical pain threshold in rats of each group after surgery was detected.The expressions of Kv1.1 and miR-21-5p in the operative TG of rats were detected by Western blotting and real-time reverse transcription polymerase chain reaction.Dual luciferase reporter genes were used to determine whether there was a target relationship between Kv1.1 and miR-21-5p and whether miR-21-5p directly affected the 3'-UTR terminal of KCNA1.The effect of brain stereotaxic injection was evaluated by immunofluorescence assay,and then the analogue of miR-21-5p(agomir)and agomir NC were injected into the TG of rats in the sham group by brain stereotaxic apparatus to overexpress miR-21-5p.The miR-21-5p inhibitor(antagomir)and antagomir NC were injected into TG of rats in the TN group to inhibit the expression of miR-21-5p.The behavioral changes of rats before and after administration were observed,and the expression changes of miR-21-5p and Kv1.1 in TG of rats after intervention were detected. Results:Compared with the baseline pain threshold,the facial mechanical pain threshold of rats in the TN group was significantly decreased from the 5th to 15th day after the surgery(P<0.05),and the facial mechanical pain threshold of rats in the sham group was stable at the normal level,which proved that the dIoN-CCI model was successfully constructed.Compared with the sham group,the expression of Kv1.1 mRNA and protein in TG of the TN group was down-regulated(both P<0.05),and the expression of miR-21-5p was up-regulated(P<0.05).The results of dual luciferase report showed that the luciferase activity of rno-miR-21-5p mimics and KCNA1 WT transfected with 6 nmol/L or 20 nmol/L were significantly decreased compared with those transfected with mimic NC and wild-type KCNA1 WT,respectively(P<0.001).Compared with low dose rno-miR-21-5p mimics(6 nmol/L)co-transfection group,the relative activity of luciferase in the high dose rno-miR-21-5p mimics(20 nmol/L)cotransfection group was significantly decreased(P<0.001).The results of immunofluorescence showed that drugs were accurately injected into TG through stereotaxic brain.After the expression of miR-21-5p in the TN group,the mechanical pain threshold and the expression of Kv1.1 mRNA and protein in TG were increased.After overexpression of miR-21-5p in the sham group,the mechanical pain threshold and the expression of Kv1.1 mRNA and protein in TG were decreased. Conclusion:Both Kv1.1 and miR-21-5p are involved in TN and miR-21-5p can regulate Kv1.1 expression by binding to the 3'-UTR of KCNA1.
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Aim To investigate the effect of dapagliflozin on the small conductance calcium-activated potassium channel 2 (SK2 channel) protein in the myocardium of diabetic rats and its possible mechanism of action. Methods In vivo: type 2 diabetes model was established by high-glucose and high-fat diet combined with intraperitoneal injection of low-dose streptozotocin (35 mg
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Arrhythmia is an external manifestation of cardiac electrophysiological disorder. It exists in healthy people and patients with various heart diseases, which is often associated with other cardiovascular diseases. The contraction and diastole of myocardium are inseparable from the movement of ions. There are many ion channels in the membrane and organelle membrane of myocardium. The dynamic balance of myocardial ions is vital in maintaining myocardial electrical homeostasis. Potassium ion channels that have a complex variety and a wide distribution are involved in the whole process of resting potential and action potential of cardiomyocytes. Potassium ion channels play a vital role in maintaining normal electrophysiological activity of myocardium and is one of the pathogenesis of arrhythmia. Traditional Chinese medicine(TCM)has unique advantages in treating arrhythmia for its complex active components and diverse targets. A large number of TCM preparations have definite effect on treating arrhythmia-related diseases, whose antiarrhythmic mechanism may be related to the effect on potassium channel. This article mainly reviewed the relevant studies on the active components in TCM acting on different potassium channels to provide references for clinical drug use and development.
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Humains , Canaux potassiques , Médecine traditionnelle chinoise , Antiarythmiques/usage thérapeutique , Troubles du rythme cardiaque/traitement médicamenteux , Cardiopathies/traitement médicamenteux , IonsRésumé
This study aimed to investigate the underlying mechanism of Zhenwu Decoction in the treatment of heart failure by regulating electrical remodeling through the transient outward potassium current(I_(to))/voltage-gated potassium(Kv) channels. Five normal SD rats were intragastrically administered with Zhenwu Decoction granules to prepare drug-containing serum, and another seven normal SD rats received an equal amount of distilled water to prepare blank serum. H9c2 cardiomyocytes underwent conventional passage and were treated with angiotensin Ⅱ(AngⅡ) for 24 h. Subsequently, 2%, 4%, and 8% drug-containing serum, simvastatin(SIM), and BaCl_2 were used to interfere in H9c2 cardiomyocytes for 24 h. The cells were divided into a control group [N, 10% blank serum + 90% high-glucose DMEM(DMEM-H)], a model group(M, AngⅡ + 10% blank serum + 90% DMEM-H), a low-dose Zhenwu Decoction-containing serum group(Z1, AngⅡ + 2% drug-containing serum of Zhenwu Decoction + 8% blank serum + 90% DMEM-H), a medium-dose Zhenwu Decoction-containing serum group(Z2, AngⅡ + 4% drug-containing serum of Zhenwu Decoc-tion + 6% blank serum + 90% DMEM-H), a high-dose Zhenwu Decoction-containing serum group(Z3, AngⅡ + 8% drug-containing serum of Zhenwu Decoction + 2% blank serum + 90% DMEM-H), an inducer group(YD, AngⅡ + SIM + 10% blank serum + 90% DMEM-H), and an inhibitor group(YZ, AngⅡ + BaCl_2 + 10% blank serum + 90% DMEM-H). The content of ANP in cell extracts of each group was detected by ELISA. The relative mRNA expression levels of ANP, Kv1.4, Kv4.2, Kv4.3, DPP6, and KChIP2 were detected by real-time quantitative PCR. The protein expression of Kv1.4, Kv4.2, Kv4.3, DPP6, and KChIP2 was detected by Western blot. I_(to) was detected by the whole cell patch-clamp technique. The results showed that Zhenwu Decoction at low, medium, and high doses could effectively reduce the surface area of cardiomyocytes. Compared with the M group, the Z1, Z2, Z3, and YD groups showed decreased ANP content and mRNA level, increased protein and mRNA expression of Kv4.2, Kv4.3, DPP6, and KChIP2, and decreased protein and mRNA expression of Kv1.4, and the aforementioned changes were the most notable in the Z3 group. Compared with the N group, the Z1, Z2, and Z3 groups showed significantly increased peak current and current density of I_(to). The results indicate that Zhenwu Decoction can regulate myocardial remodeling and electrical remodeling by improving the expression trend of Kv1.4, Kv4.2, Kv4.3, KChIP2, and DPP6 proteins and inducing I_(to) to regulate Kv channels, which may be one of the mechanisms of Zhenwu Decoction in treating heart failure and related arrhythmias.
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Rats , Animaux , Myocytes cardiaques , Remodelage auriculaire , Rat Sprague-Dawley , Défaillance cardiaque/métabolisme , ARN messager/métabolisme , PotassiumRésumé
ObjectiveTo observe the changes in the expression and distribution of G protein-gated inwardly rectifying potassium channel subunit 2 (GIRK2) in the dorsal root ganglion (DRG) and spinal cord dorsal horn of rats with remifentanil-induced hyperalgesia. MethodsHyperalgesia was induced by intravenous infusion of remifentanil 4 μg/kg/min for 2 h in adult male SD rats. At 6th hour and on days 1, 3 and 5 following remifentanil treatment, we used immunofluorescence to examine the changes in the GIRK2 distribution and expression. Immunoblotting was used to detect GIRK2 expression of the total protein and membrane protein in DRG and spinal dorsal horn of rats. Behavioral testing was applied to evaluate the effect of intrathecal injection of GIRK2-specific agonist ML297 on thermal nociceptive threshold on day 1 after remifentanil infusion. Resultsmmunofluorescence results showed that GIRK2 was mainly co-localized with IB4-positive small neurons in DRG and nerve fibers in spinal dorsal horn. GIRK2 expression was significantly downregulated following remifentanil treatment. Immunoblotting results revealed that on day 1 following intravenous infusion of remifentanil, compared with those in the control group, GIRK2 expression levels of the total protein and membrane protein in DRG (0.47 ± 0.10 vs. 1.01 ± 0.17, P < 0.001; 0.47 ± 0.11 vs. 1.06 ± 0.12, P < 0.001) and spinal dorsal horn (0.52 ± 0.09 vs. 1.10 ± 0.08, P < 0.001; 0.54 ± 0.10 vs. 1.01 ± 0.13, P < 0.001) were all significantly decreased. The behavioral results showed that intrathecal ML297 effect on thermal withdrawal latency was significantly reduced following remifentanil treatment (P < 0.001). ConclusionsRemifentanil might induce hyperalgesia via down-regulating GIRK2 expression in rat DRG and spinal cord dorsal horn.
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Aim To investigate the insulinotropic effect of telmisartan anrl the underlying electrophysiological mechanism.Methods Islets and cells were isolated from Wistar rats.Islets were incubated with drugs un¬der different conditions, then supernatant liquid was collected for insulin secretion.Intracellular Ca" + ( Ca'+ j) levels of (3-cells were measured by calcium imaging technology.Patch-clamp technology was ap¬plied to detect effects on voltage-gated potassium chan¬nel ( Kv ) , and voltage-gated calcium channel ( VGCC ).Results Not affecting insulin secretion un¬der low glucose condition, telmisartan dose-dependent- ly stimulated insulin secretion under high glucose con¬ dition, and stimulation was enhanced with increasing glucose concentration.Acute increases of Ca' + concentration were elicited by telmisartan under high glucose condition.Telmisartan decreased current den¬sity of Kv channel, and increased VGCC current densi¬ty.Conclusions Telmisartan enhanced Ca~+ ; lev¬els of p-cells through its action on Kv channel and VGCC, thereby amplifying glucose-stimulated insulin secretion.
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Two-pore domain potassium channels (K2P) make up a subfamily of potassium channels discovered in the 1990s, and TREK-1 is the most widely studied subtype of K2P. TREK-1 is widely expressed in the body and especially in the central nervous system, where its main role is to control cell excitability and maintain the membrane potential below the depolarization threshold. It thereby participates in regulating various physiological and pathological processes. TREK-1 is also a potential drug target in many diseases. It is known that many marketed drugs can affect the function of TREK-1, but currently there are no specific TREK-1 modulators or drugs. We review the structure, distribution and regulation of TREK-1 and focus on recent progress in understanding the pharmacology of TREK-1 and its role in neuroprotection, depression, anesthesia and epilepsy. The research status of TREK-1 modulators is discussed.
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In vascular smooth muscle, K⁺ channels, such as voltage-gated K⁺ channels (Kv), inward-rectifier K⁺ channels (Kir), and big-conductance Ca²⁺-activated K⁺ channels (BK(Ca)), establish a hyperpolarized membrane potential and counterbalance the depolarizing vasoactive stimuli. Additionally, Kir mediates endothelium-dependent hyperpolarization and the active hyperemia response in various vessels, including the coronary artery. Pulmonary arterial hypertension (PAH) induces right ventricular hypertrophy (RVH), thereby elevating the risk of ischemia and right heart failure. Here, using the whole-cell patch-clamp technique, we compared Kv and Kir current densities (I(Kv) and I(Kir)) in the left (LCSMCs), right (RCSMCs), and septal branches of coronary smooth muscle cells (SCSMCs) from control and monocrotaline (MCT)-induced PAH rats exhibiting RVH. In control rats, (1) I(Kv) was larger in RCSMCs than that in SCSMCs and LCSMCs, (2) I(Kv) inactivation occurred at more negative voltages in SCSMCs than those in RCSMCs and LCSMCs, (3) I(Kir) was smaller in SCSMCs than that in RCSMCs and LCSMCs, and (4) I(BKCa) did not differ between branches. Moreover, in PAH rats, I(Kir) and I(Kv) decreased in SCSMCs, but not in RCSMCs or LCSMCs, and I(BKCa) did not change in any of the branches. These results demonstrated that SCSMC-specific decreases in I(Kv) and I(Kir) occur in an MCT-induced PAH model, thereby offering insights into the potential pathophysiological implications of coronary blood flow regulation in right heart disease. Furthermore, the relatively smaller I(Kir) in SCSMCs suggested a less effective vasodilatory response in the septal region to the moderate increase in extracellular K⁺ concentration under increased activity of the myocardium.
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Animaux , Rats , Vaisseaux coronaires , Cardiopathies , Défaillance cardiaque , Hyperhémie , Hypertension artérielle , Hypertrophie ventriculaire droite , Ischémie , Potentiels de membrane , Monocrotaline , Muscles lisses , Muscles lisses vasculaires , Myocarde , Myocytes du muscle lisse , Techniques de patch-clamp , Canaux potassiques , Septum du cerveauRésumé
Objective:To observe the effect of Shuangshen Ningxin capsule in alleviating myocardial ischemia/reperfusion injury in rats by regulating mitochondrial adenosine triphosphate(ATP)-sensitive potassium channels.Method:A total of 56 adult male Sprague-Dawley rats were randomly divided into sham-operated control group (sham), model group (model), Shuangshen Ningxin group (SSNX, 90 mg·kg-1).Shuangshen Ningxin and mitochondrial ATP-sensitive potassium channel (MitoKATP) channel inhibitor group 5-hydroxyl-acid group (SSNX+5-HD, 5 mg·kg-1), with 14 rats in each group. Except the sham operation group, the other three groups received occlusion of left anterior descending coronary artery (LAD) for 45 min, and were sacrificed 3 h after reperfusion. Myocardial ischemia and infarct size were observed by TSC Evans blue staining, and myocardial tissue damage degree was observed by hematoxylin-eosin(HE) staining. The kit was used to measure serum lactate dehydrogenase (LDH), creatine kinase (CK) and creatine kinase isoenzyme (CK-MB). The ultrastructural changes of mitochondria and mitochondrial autophagy were observed under transmission electron microscope. The changes of mitochondrial membrane potential in cardiomyocytes were detected by fluorescent probe.Result:Compared with the sham group, myocardial infarct size and myocardial ischemic area percentage in the model group were significantly increased, myocardial tissue arrangement was disordered and loose, individual myocardial fibers were broken, cardiomyocytes were necrotic, and serum CK, CK-MB, LDH activities were significantly increased (P<0.01). Mitochondrial membrane potential was significantly decreased (P<0.01), and mitochondrial structure was destroyed by transmission electron microscopy. Compared with the model group, the myocardial tissue of the SSNX group was arranged orderly, and a small amount of cell edema was mildly degenerated. The percentage of myocardial infarct size and myocardial ischemic area was significantly decreased, serum CK, CK-MB, and LDH activities were significantly decreased (P<0.01), while mitochondrial membrane potential increased (P<0.01). Compared with the model group, the SSNX+5-HD group had mild myocardial tissue disorder and mild degeneration of cell edema in some areas, the percentage of myocardial infarct size and myocardial ischemic area was significantly reduced, serum CK, CK-MB, and LDH activities were significantly decreased (P<0.01), and mitochondrial membrane potential increased (P<0.01). Compared with SSNX group, SSNX+5-HD group had significant increase in serum CK, CK-MB and LDH activities (P<0.01), significant increase in the percentage of myocardial infarct size and myocardial ischemic area, and mitochondrial membrane potential Reduced (P<0.05).Conclusion:SSNX protects rat myocardial ischemia-reperfusion injury by opening mitochondrial ATP-sensitive potassium channel.
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OBJECTIVE@#To investigate the changes in the expression of voltage-gated potassium channel subunit KCNA2 in the dorsal root ganglion (DRG) neurons of rats with osteoarthritis (OA) pain induced by sodium monoiodoacetate and explore the mechanism.@*METHODS@#A total of 156 adult male Sprague-Dawley rats were randomly divided into blank control group, saline group and intra-articular monoiodoacetate injection-induced OA group. The paw withdrawal mechanical threshold (PWMT) was measured before and at 1, 2, 4, and 6 weeks after monoiodoacetate injection. At 4 weeks after the injection, the pathological changes in the knee joints were analyzed using HE staining and Safranin O-Fast Green staining, and the expression of activating transcription factor 3 (ATF-3) and inducible nitric oxide synthase (iNOS) in the DRG neurons were detected by immunofluorescence staining. The expression of mRNA in the DRG neurons was detected by RT-qPCR at 1, 2, 4 and 6 weeks after the injection. The expression of KCNA2 in the DRG was measured by Western blotting, and the methylation level of promoter region was measured by MSPCR at 4 weeks after the injection.@*RESULTS@#The PWMT of the rats in OA group was significantly decreased at 2, 4, and 6 weeks after the injection as compared with the baseline ( < 0.05 or < 0.001) as well as the control group ( < 0.05 or < 0.001). Four weeks after the intra-articular injection, fractures and defects on the surface of the articular cartilage, bone hyperplasia, and blurred tidal line were observed in the rats in OA group, but no obvious pathological changes were detected in the control or saline groups. Compared with those in the control group, the expressions of ATF-3 and iNOS were significantly increased ( < 0.01) at 4 weeks after injection; the expression of mRNA at 2, 4 and 6 weeks and the expression of KCNA2 protein at 4 weeks were all significantly decreased ( < 0.05 or < 0.01), and the methylation level of gene was significantly increased at 4 weeks after the injection in OA group ( < 0.01).@*CONCLUSIONS@#The expression of KCNA2 is decreased in the DRG neurons of rats with OA pain likely as a result of enhanced methylation of promoter region.
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Animaux , Mâle , Rats , Modèles animaux de maladie humaine , Ganglions sensitifs des nerfs spinaux , Articulation du genou , Métabolisme , Arthrose , Métabolisme , Douleur , Métabolisme , Régions promotrices (génétique) , Rat Sprague-DawleyRésumé
Objective • To observe the effect of protease activated receptor 2 (PAR2) on the colonic motility in diabetic mice and investigate the mechanism. Methods • The mouse model of type 1 diabetes mellitus was established by intraperitoneal injection of streptozotocin. The smooth muscle strips and segments of colons were isolated. The effects of PAR2 agonist on colonic motility were observed by muscle strip tension contraction and colonic migrating motor complex experiments. The effect of small conductance calcium-activated potassium channel (SK3 channel) antagonist on it was also observed. Results • PAR2 agonist inhibited colonic motility and colonic smooth muscle was more sensitive to PAR2 agonist in diabetic mice. PAR2 agonist-induced inhibition was inhibited by SK3 channel antagonist. Conclusion • PAR2 activity in diabetic mice colons is significantly enhanced, which may inhibit colonic motility through SK3 channel.
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Objective: To construct stable cell lines expressing the large conductance Ca2+-activated K+ channel (MaxiK or BK) α-subunit and to explore the mechanism of potassium excretion via BKα channel. Methods:The BKα plasmid with Myc tag was constructed and transfected into HEK293 cell lines by lipofectamine 2000. The positive monoclonal cell lines were screened by G418, and the expression of BKα was detected by Western blotting and the location of BKα by immunofluorescence. The stable cell lines expressing BKα protein was cultured on slides to form a single cell layer, which was perfused with different potassium ion concentrations of 5 mmol/L and 100 mmol/L, and the single channel patch clamp recorded the ion flux of BKα. Wild type and mutants (G77R, G130R, C140R and R297C) of the inwardly rectifying potassium channel (Kir4.1) were transfected into HEK293 cells stably transfected with BKα, and then the membrane protein was extracted. The expression of BKα was detected by Western blotting. Results:Stable cell lines expressing BKα channel were selected from HEK293 cells after transfection and cellular immunofluorescence verified the expression of BKα channel and its expression on the cell membrane. The channel open frequency (Npo) of BKα increased rapidly when perfused with 100 mmol/L potassium. After being transfected with wild type or mutants of Kir4.1, the membrane expression of BKα in the stable cell lines showed significant difference among these groups (P<0.05). Conclusion:The HEK293 cell lines stably expressing BKα have been successfully constructed. BKα channel can be activated by high potassium solutions. The function of the BKα subunit can be related to Kir4.1 channel, which may be attributed to the depolarization of the cells transfected by Kir4.1 mutants.
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Objective: To study the antitussive effect of Sauropus spatulifolius, screen the active part of its antitussive effect, and study its antitussive mechanism. Methods The acute toxicity of different extraction sites of S. spatulifolius were studied by modified Karber’s method; The model was made with ammonia liquor to induce cough. The spray time that caused half of the mice to cough was calculated by sequential method with aim to screen the active sites. Capsaicin was used to induce cough, and the mechanism of action of extracts from various parts of S. spatulifolius on opioid receptor and ATP-sensitive potassium channel (KATP) of mice was explored. Results The LD50 of 75% ethanol, ethyl acetate, n-butanol, and 95% ethanol extracts was 7.30, 17.00, 69.68, and 75.88 g/kg, respectively; The maximum tolerance dose (MTD) of petroleum ether extracts was 117.71 g/kg; Extracts from 75% ethanol and ethyl acetate had antitussive effects, and its antitussive effect was related to opioid receptor and KATP pathway. Conclusion The fractions from 75% ethanol and ethyl acetate are the active parts of S. spatulifolius for relieving cough, and its antitussive mechanism is related to the KATP pathway and opioid receptors in the excited central system.
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OBJECTIVE: To investigate the vasodilatory effect mechanism of psoralen and bakuchiol. METHODS: The rat thoracic aorta was isolated to prepare vascular rings and de-endothelium vascular rings. Using contraction rate as index, the intact endothelium or de-endothelium vascular rings were pre-incubated with N-nitro-L-arginine methyl ester (L-NAME, 100 μmol/L); vasodilatory effect of low-dose, medium-dose and high-dose of psoralen or bakuchiol(0.1,1,10 μmol/L)on aortic vessels pre- contracted with norepinephrine (NE, 1 μmol/L) or potassium chloride (KCl, 60 mmol/L) were investigated. The de-endothelium vascular rings were pre-incubated with calcium dependent potassium channel inhibitors tetraethylammonium chloride (TEA, 0.1 mmol/L) and inward rectifying potassium channel inhibitor barium chloride (BaCl2,0.1 mmol/L); vasodilatory effect of low-dose, medium-dose and high-dose of bakuchiol (0.1, 1, 10 μmol/L) on de-endothelium vascular vessels pre-contracted with NE (1 μmol/L) were investigated. The microvascular endothelial cells were isolated by collagenase-neutral protease digestion; the effects of low-dose, medium-dose and high-dose of psoralen or bakuchiol (0.1, 1, 10 μmol/L) on the expression of eNOS protein were studied by ELISA. RESULTS: Psoralen and bakuchiol could significantly reduce the contraction rate of endothelium-intact aortic rings pre-contracted with NE(P<0.01); medium-dose and high-dose of psoralen and bakuchiol could significantly reduce the contraction rate of endothelium-intact aortic rings pre-contracted with KCl(P<0.05 or P<0.01); while the contraction rate could be increased by de-endothelium and NOS inhibition significantly (P<0.05 or P<0.01). The medium-dose and high-dose of bakuchiol could significantly reduce the contraction rate of de-endothelium vascular vessels pre-contracted with NE (P<0.05 or P<0.01). The contraction rate could be increased by inhibiting inward rectifier potassium channels in vascular smooth muscle (P<0.01). Different dosages of psoralen and bakuchiol could significantly increase the expression levels of eNOS protein in rat cardiac microvascular endothelial cells(P<0.01). CONCLUSIONS: Psoralen and bakuchiol may play a role in vasodilation via endothelium-dependent NO pathway and by promoting eNOS protein expression in endothelial cells; bakuchiol may play a role in vasodilation via non-endothelium dependent pathway as opening inward rectifying potassium channel.
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OBJECTIVE: To study the vasodilatory effect of oxysophocarpine (OSC) on isolated thoracic aortic rings of rats and its possible mechanism. METHODS: Thoracic aortic rings of rats were collected (called “vascular ring” for short). Using K-H nutrient solution as blank control and the diastolic rate as index, the effects of different concentrations (0.2-1.0 mg/mL) of OSC on normal vascular rings in basal state, normal or endothelium-free vascular rings pre-contracted by norepinephrine (PE, 1×10-6 mol/L) were investigated. After pre-culturing normal thoracic aortic rings by nitric oxide synthase inhibitor L-nitro-arginine methyl ester(L-NAME)and cyclooxygenase inhibitor indomethacin(INDO),as well as pre-culturing endothelium-free vascular rings by potassium ion channel blocker BaCl2,tetraethylammonium(TEA)and 4-aminopyridine(4-AP), the diastolic effects of OSC of different concentrations (0.2-1.0 mg/mL) on the above vascular rings were investigated by using the same method. RESULTS: Compared with blank control, there was no significant effects of different concentrations of OSC on the diastolic rate of normal vascular rings in basal state (P>0.05), but 0.4-1.0 mg/mL OSC could significantly improve the diastolic rate of normal or endothelium-free vascular rings pre-contracted by PE (P<0.01), in concentration-dependent manner. After preculturing with L-NAME, INDO, 4-AP and BaCl2, different concentrations of OSC had no significant effect on the diastolic rate of normal or endothelium-free vascular rings pre-contracted by PE (P>0.05). After pre-culturing with TEA and Gli, 0.4-1.0 mg/mL OSC could significantly reduce the diastolic rate of endothelium-free vas- cular rings pre-contracted by PE (P<0.01). CONCLUSIONS: OSC did not significantly dilate the thoracic aortic rings of rats in the basal state within the dose range (0.2-1.0 mg/mL), but OSC of 0.4-1.0 mg/mL have significant diastolic effects on the normal or endothelium-free thoracic aortic rings of rats pre-contracted with PE. The mechanism of thoracic aortic rings dilation is endothelium-independent, which may be associated with receptor operational calcium channel,Ca2+-activated potassium channels and ATP-sensitive potassium channels.
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General anesthesia is an unconscious state induced by anesthetics for surgery. The molecular targets and cellular mechanisms of general anesthetics in the mammalian nervous system have been investigated during past decades. In recent years, K channels have been identified as important targets of both volatile and intravenous anesthetics. This review covers achievements that have been made both on the regulatory effect of general anesthetics on the activity of K channels and their underlying mechanisms. Advances in research on the modulation of K channels by general anesthetics are summarized and categorized according to four large K channel families based on their amino-acid sequence homology. In addition, research achievements on the roles of K channels in general anesthesia in vivo, especially with regard to studies using mice with K channel knockout, are particularly emphasized.
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Animaux , Humains , Anesthésiques généraux , Pharmacologie , Utilisations thérapeutiques , Canaux potassiques , MétabolismeRésumé
OBJECTIVE@#To observe the mechanism of "" acupuncture for the opening of ATP sensitive potassium channel (K) against cerebral ischemia reperfusion injury in rats.@*METHODS@#Eighty-four rats were randomly divided into a sham-operation group, a model group, an electroacupuncture (EA) group, an EA+K blocker group, 21 rats in each group. 10 μL intracerebral injection with glipizide (1 μmol/5 μL) was used in the EA+K blocker group. The cerebral ischemia reperfusion model was established by Zea Longa's suture method in the model group, the EA group and the EA+K blocker group. Rats in the sham-operation group were received the same surgery but without nylon filament insertion. Acupuncture (20 min a time) was performed at "Neiguan" (PC 6), "Shuigou" (GV 26) and "Sanyinjiao" (SP 6) in the EA group and the EA+K blocker group at 10:00 and 16:00 for 3 days, firstly 90 min after model establishment. EA (2 Hz/15 Hz, 1 mA) was connected at the affected "Neiguan" (PC 6) and "Sanyinjiao" (SP 6). The same fixation was used in the sham-operation group and the model group, without EA. Neurological function was assessed by Zausinger's neurologic assessment scale. 2, 3, 5-triphenyltetrazolium chloride (TTC) staining was used to detect infarct volume. Neurocyte apoptosis in the hippocampus was detected by flow cytometry and the protein expressions of B lymphocytoma-2 gene (Bcl-2) and B cell lymphoma factor-associated X protein (Bax) were measured by Western-blot.@*RESULTS@#In comparison with the model group, the neurological score of the EA group increased (<0.01); the infarction volume and the hippocampal neuron's total apoptosis rate of the EA group decreased (both <0.05); the protein expression of Bcl-2 and Bcl-2/Bax of the EA group increased (<0.05, <0.01); and the protein expression of Bax of the EA group decreased (<0.01). Compared with the EA group, the neurological score of the EA+K blocker group decreased (<0.05); the total apoptosis rate of hippocampus neurons of the EA+K blocker group increased (<0.05); the expression of Bcl-2 protein of the EA+K blocker group reduced (<0.05); the expression of Bax protein of the EA+K blocker group increased (<0.05).@*CONCLUSION@#"" acupuncture has brain protective effect on rats with focal cerebral ischemia reperfusion injury. The mechanism may be related to regulating the opening of K channels and decreasing the apoptosis of neurons.
Sujets)
Animaux , Rats , Points d'acupuncture , Encéphalopathie ischémique , Électroacupuncture , Canaux KATP , Rat Sprague-Dawley , Lésion d'ischémie-reperfusionRésumé
Objective To investigate the vasodilating effects of protocatechuic aldehyde (PCA ) on rat superior mesenteric arterial rings as well as its mechanism .Methods The tension of rat superior mesenteric arterial rings was recorded by a sensitive myograph system in vitro . We measured isometric tension changes in preconstricted rat superior mesenteric artery rings induced by potassium chloride (KCl ,60 mmol/L) ,serotomin (5-HT ,10-5 mol/L ) , and phenylephrine (PE , 10-5 mol/L ) after PCA treatment at different concentrations , respectively .We also observed vasodilating effects of PCA on KCl (60 mmol/L ) preconstricted rat superior mesenteric arterial rings after incubation with different inhibitors ,i .e .,L-NAME ,Indo ,ODQ ,4-AP (KV channel blocker) ,TEA (KCa channel blocker) ,BaCl2 (Kir channel blocker) ,and Glib (KATP channel blocker) ,respectively . Results PCA (10-6 -10-3 mol/L ) could relax KCl (60 mmol/L ) and 5-HT (10-5 mol/L ) preconstricted rat superior mesenteric arterial rings in a concentration-dependent manner . Indo of endothelial mechanism inhibitor blocked the vasodilating effect of PCA . 4-AP and BaCl2 of potassium ion channel inhibitors affected the vasodilatation induced by PCA in KCl (60 mmol/L)-preconstricted rat mesenteric artery .Conclusion PCA can relax KCl (60 mmol/L) ,or 5-HT preconstricted rat superior mesenteric arterial rings .This effect is associated with the inhibition of potassium channels and endothelial mechanism .
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Aim To investigate the alteration of volt-age-depending potassium channel(KV) current in pul-monary arterial smooth muscle cells(PASMCs) of pul-monary hypertension (PH) rats, and the effect of tet-raethylammonium (TEA,a blocker of KV) on potassi-um channel current in different PH models. Methods The whole-cell patch clamp techniques were applied to record the KVcurrents from PASMCs cultured with Ham's F-12 (1% FBS). Furthermore, the effects of TEA on the KVcurrents were examined in different PH models. Results The whole-cell KVcurrents were ob-viously inhibited in PASMCs of chronic hypoxia (CH)and monocrotaline (MCT)-treated rats. TEA signifi-cantly decreased the whole-cell KVcurrents in PASMCs of control and PH rats,and the inhibitory effect of TEA was dramatically reduced in PH group. Conclusions The degree of the voltage-dependent potassium chan-nels opening is significantly inhibited in PASMCs of CH and MCT-treated rats,accordingly,the TEA-sen-sitive KVcurrents obviously decrease.
Résumé
<p><b>OBJECTIVE</b>To investigate the changes of the two- pore K channel TASK-1 in diabetic rats with myocardial injury.</p><p><b>METHODS</b>Thirty-six SD rats were divided into normal group (N), diabetes at 4 weeks (DM 4W) group, and diabetes at 8 weeks (DM 8W) group. The cardiac functions of the rats were determined using cardiac ultrasonography, and the body weight and heart weight of the rats at different time points were measured to calculate the heart/body weight ratio (HW/BW). Myocardial fibrosis in the rats was assessed using Masson's staining. The protein expression of TASK-1 in the myocardium was detected using Western blotting. Whole- cell patch clamp technique was used to record the action potential duration (APD) and twopore domain potassium channel TASK- 1 current in acutely isolated rat ventricular myocytes. meanwhile, The inhibition of TASK-1 current was observed by the TASK-1 specific inhibitor ML-365.</p><p><b>RESULTS</b>Compared with the normal group, the diabetic rats showed significantly increased HW/BW ( < 0.05), end- diastole left ventricular diameter (LVIDd), end- systolic left ventricular diameter (LVIDs), and TASK-1 protein expression, with obviously decreased left ventricular diameter shortening rate (FS) and ejection fraction (EF) ( < 0.01). Masson staining showed that in diabetic rats, the collagen fibers were thickened, interwoven into a network with uneven arrangement and increased deposition. Compared with DM 4W group, the rats in DM 8W group exhibited progressive increases in LVIDd, LVIDs, HW/BW, and TASK-1 expression ( < 0.01 or 0.05); FS and EF were further decreased ( < 0.01). Masson staining showed worsened morphological changes of the myocardium with increased deposition. Compared with that in the normal group, the current of TASK- 1 in diabetic rats at 8 weeks was significantly reduced ( < 0.01) and the duration of action potential was extended ( < 0.05). The TASK-1 current was successfully inhibited by ML-365.</p><p><b>CONCLUSIONS</b>Diabetes can induce myocardial fibrosis and aggravate myocardial injury possibly in relation to changes in the protein expression and current of the two-port potassium channel TASK-1.</p>