Effects of Mitochondrial ATP-sensitive K^+ Channel on Protein Kinase C Pathway and Airway Smooth Muscle Cell Proliferation in Asthma

The effects of ATP-sensitive mitochondrial K + channel(mitoK ATP) on mitochondrial membrane potential(Δψm),cell proliferation and protein kinase C alpha(PKCα) expression in airway smooth muscle cells(ASMCs) were investigated.Thirty-six Sprague-Dawley(SD) rats were immunized with saline(controls) or ovalbumin(OVA) with alum(asthma models).ASMCs were cultured from the lung of control and asthma rats.ASMCs were treated with diazoxide(the potent activator of mitoK ATP) or 5-hydroxydencanote(5-HD,the inhibitor of mitoK ATP).Rhodamine-123(R-123) was used to detect Δψm.The expression of PKCα protein was examined by using Western blotting,while PKCα mRNA expression was detected by using real-time PCR.The proliferation of ASMCs was measured by MTT assay and cell cycle analysis.In diazoxide-treated normal ASMCs,the R-123 fluorescence intensity,protein and mRNA levels of PKCα,MTT A values and percentage of cells in S phase were markedly increased as compared with untreated controls.The ratio of G 0 /G 1 cells was decreased(P<0.05) in diazoxide-treated ASMCs from normal rats.However,there were no significant differences between the ASMCs from healthy rats treated with 5-HD and the normal control group.In untreated and diazoxide-treated ASMCs of asthmatic rats,the R-123 fluorescence intensity,protein and mRNA levels of PKCα,MTT A values and the percentage of cells in S phase were increased in comparison to the normal control group.Furthermore,in comparison to ASMCs from asthmatic rats,these values were considerably increased in asthmatic group treated with diazoxide(P<0.05).After exposure to 5-HD for 24 h,these values were decreased as compared with asthma control group(P<0.05).In ASMCs of asthma,the signal transduction pathway of PKCα may be involved in cell proliferation,which is induced by the opening of mitoK ATP and the depolarization of Δψm.

Localization of ATP-sensitive K^+ channel subunits in rat liver

BACKGROUND ATP-sensitive K^+(KATP)channels were originally found in cardiac myocytes by Noma in 1983.KATP channels were formed by potassium ion-passing poreforming subunits(Kir6.1,Kir6.2)and regulatory subunits SUR1,SU2A and SUR2B.A number of cells and tissues have been revealed to contain these channels including hepatocytes,but detailed localization of these subunits in different types of liver cells was still uncertain.AIM To investigate the expression of KATP channel subunits in rat liver and their localization in different cells of the liver.METHODS Rabbit anti-rat SUR1 peptide antibody was raised and purified by antigen immunoaffinity column chromatography.Four of Sprague-Dawley rats were used for liver protein extraction for immunoblot analysis,seven of them were used for immunohistochemistry both for the ABC method and immunofluorescence staining.Four of Wistar rats were used for the isolation of hepatic stellate cells(HSCs)and Kupffer cells for both primary culture and immunocytochemistry.RESULTS Immunoblot analysis showed that the five kinds of KATP channel subunits,i.e.Kir6.1,Kir6.2,SUR1,SUR2A,and SUR2B,were detected in liver.Immunohistochemical staining showed that Kir6.1 and Kir6.2 were weakly to moderately expressed in parenchymal cells and sinusoidal lining cells,while SUR1,SUR2A,and SUR2B were mainly localized to sinusoidal lining cells,such as HSCs,Kupffer cells,and sinusoidal endothelial cells.Immunoreactivity for SUR2A and SUR2B was expressed in the hepatocyte membrane.Double immunofluorescence staining further showed that the pore-forming subunits Kir6.1 and/or Kir6.2 colocalized with GFAP in rat liver sections and primary cultured HSCs.These KATP channel subunits also colocalized with CD68 in liver sections and primary cultured Kupffer cells.The SUR subunits colocalized with GFAP in liver sections and colocalized with CD68 both in liver sections and primary cultured Kupffer cells.In addition,five KATP channel subunits colocalized with SE-1 in sinusoidal endothelial cells.CONCLUSION Observations from the present study indicated that KATP channel subunits expressed in rat liver and the diversity of KATP channel subunit composition might form different types of KATP channels.This is applicable to hepatocytes,HSCs,various types of Kupffer cells and sinusoidal endothelial cells.

Effects Of ATP Sensitive potassium channel opener on the mRNA and pro- tein expressions of caspase-12 after cerebral ischemia-reperfusion in rats

Objective To investigate effects of K_ATP opener on the expressions of caspase-12 mRNA and protein, and to explore the role of endoplasmic reticulum （ER） stress pathway in the mechanism of K_ATP opener protecting against neuronal apoptosis after cerebral ischemia-reperfusion. Methods Two hundred rats were randomly divided into four groups： sham operation group, ischemia-reperfusion group, K_ATP opener group, and K_ATP blocker group. The middle cerebral artery occlusion （MCAO） model was established by intraluminal suture occlusion method; neuronal apoptosis was detected by TUNEL staining. The mRNA and protein expressions of caspase-12 were detected by semi-quantitative RT-PCR and immunohisto-chemical staining, respectively. Results In ischemia-reperfusion group, K_ATP opener group and K_ATP blocker group, the number of apoptotic cells and the mRNA and protein expressions of caspase-12 gradually increased following cerebral reperfusion, and reached the peak at 24 h. In K_ATP opener group, The number of apoptotic cells was significantly less than that in ischemia-reperfusion group and K_ATP blocker group at 12 h, 24 h, 48 h and 72 h （P 〈 0.05 or P 〈 0.01）; while the mRNA and protein levels of caspase-12 were significantly less than those in ischemia-reperfusion group and K_ATP blocker group at all times （P 〈 0.05 or P〈0.01）. There were no differences between the ischemia-reperfusion group and K_ATP blocker group at each time （P〉 0.05）. Conclusion K_ATP opener may protect neurons from apoptosis following the cerebral ischemia-reperfusion by inhibiting ER stress pathway.

Hypoxic pulmonary hypertension and novel ATP-sensitive potassium channel opener: the new hope on the horizon

Hypoxic pulmonary hypertension(HPH) is a syndrome characterized by the increase of pulmonary vascular tone and the structural remodeling of peripheral pulmonary arteries.The aim of specific therapies for hypoxic pulmonary hypertension is to reduce pulmonary vascular resistance,reverse pulmonary vascular remodeling,and thereby improving right ventricular function.Iptakalim,a lipophilic para-amino compound with a low molecular weight,has been demonstrated to be a new selective ATP-sensitive potassium(K ATP) channel opener via pharmacological,electrophysiological,biochemical studies,and receptor binding tests.In hypoxia-induced animal models,iptakalim decreases the elevated mean pressure in pulmonary arteries,and attenuates remodeling in the right ventricle,pulmonary arteries and airways.Furthermore,iptakalim has selective antihypertensive effects,selective vasorelaxation effects on smaller arteries,and protective effects on endothelial cells,but no effects on the central nervous,respiratory,digestive or endocrine systems at therapeutic dose.Our previous studies demonstrated that iptakalim inhibited the effects of endothelin-1,reduced the intracellular calcium concentration and inhibited the proliferation of pulmonary artery smooth muscle cells.Since iptakalim has been shown safe and effective in both experimental animal models and phase I clinical trials,it can be a potential candidate of HPH in the future.

Beneficial effects of adenosine triphosphate-sensitive K^+ channel opener on liver ischemia/reperfusion injury

AIM:To investigate the effect of diazoxide administration on liver ischemia/reperfusion injury.METHODS:Wistar male rats underwent partial liver ischemia performed by clamping the pedicle from the medium and left anterior lateral segments for 1 h under mechanical ventilation.They were divided into 3 groups:Control Group,rats submitted to liver manipulation,Saline Group,rats received saline,and Diazoxide Group,rats received intravenous injection diazoxide(3.5 mg/kg) 15 min before liver reperfusion.4 h and 24 h after reperfusion,blood was collected for determination of aspartate transaminase(AST),alanine transaminase(ALT),tumor necrosis factor(TNF-α),interleukin-6(IL-6),interleukin-10(IL-10),nitrite/nitrate,creatinine and tumor growth factor-β1(TGF-β1).Liver tissues were assembled for mitochondrial oxidation and phosphorylation,malondialdehyde(MDA) content,and histologic analysis.Pulmonary vascular permeability and myeloperoxidase(MPO) were also determined.RESULTS:Four hours after reperfusion the diazoxide group presented with significant reduction of AST(2009 ± 257 U/L vs 3523 ± 424 U/L,P = 0.005); ALT(1794 ± 295 U/L vs 3316 ± 413 U/L,P = 0.005); TNF-α(17 ± 9 pg/mL vs 152 ± 43 pg/mL,P = 0.013; IL-6(62 ± 18 pg/mL vs 281 ± 92 pg/mL); IL-10(40 ± 9 pg/mL vs 78 ± 10 pg/mL P = 0.03),and nitrite/nitrate(3.8 ± 0.9 μmol/L vs 10.2 ± 2.4 μmol/L,P = 0.025) when compared to the saline group.A significant reduction in liver mitochondrial dysfunction was observed in the diazoxide group compared to the saline group(P < 0.05).No differences in liver MDA content,serum creatinine,pulmonary vascular permeability and MPO activity were observed between groups.Twenty four hours after reperfusion the diazoxide group showed a reduction of AST(495 ± 78 U/L vs 978 ± 192 U/L,P = 0.032); ALT(335 ± 59 U/L vs 742 ± 182 U/L,P = 0.048),and TGF-β1(11 ± 1 ng/mL vs 17 ± 0.5 ng/mL,P = 0.004) serum levels when compared to the saline group.The control group did not present alterations when compared to the diazoxide and saline groups.CONCLUSION:Diazoxide maintains liver mitochondrial function,increases liver tolerance to ischemia/reperfusion injury,and reduces the systemic inflammatory response.These effects require further evaluation for using in a clinical setting.

Effects of acupuncture combined with Kaijingtongmai Decoction on ATP sensitive potassium channel related proteins Kir6.1 and Kir6.2 in myocardial infarction rats

Objective:To study the effect of combination of acupuncture and medicine on the expression of ATP sensitive potassium channel related proteins Kir6.1 and Kir6.2 in rats with myocardial infarction,and to study the possible mechanism of combination of acupuncture and medicine on the improvement of myocardial infarction,so as to provide experimental data basis for the development of new treatment methods for myocardial infarction.Methods:65 healthy male SD rats were randomly selected as the control group.The other rats were fed with high-fat food for three weeks.The rats in the control group were injected with normal saline subcutaneously,and the other rats were injected with isoproterenol hydrochloride in the same way.Through ECG comparison,40 successful Mi rats were randomly divided into model group,acupuncture group,western medicine group and acupuncture drug combination group,with 10 rats in each group.After the corresponding treatment,the ECG changes of rats in each group were observed,the pathological changes of rat cardiomyocytes were observed by HE staining,and the expression of ATP sensitive potassium channel(Kir6.1,Kir6.2)protein was detected by Western blot.Results:compared with the control group,40 experimental specimens in the experimental group showed significant changes in cardiomyocyte protein The expression of Kir6.1 and Kir6.2 increased,and the difference was statistically significant.After treatment,compared with the model group,the protein expression of Kir6.1 and Kir6.2 in cardiomyocytes of Western medicine group,acupuncture group and acupuncture drug combination group showed a downward trend,among which the decline degree of acupuncture drug combination group was the most obvious,and the difference was statistically significant.The decline degree of acupuncture group and Western medicine group was not significant,and there was no significant difference Conclusion:acupuncture combined with medicine has a significant effect on improving myocardial infarction in rats,which may be related to the expression of ATP sensitive potassium channel related proteins Kir6.1 and Kir6.2 in rat cardiomyocytes.

Effect of G_(αq/11) Protein and ATP-sensitive Potassium Channels on Ischemic Preconditioning in Rat Hearts

Objectives To investigate the effect of Gαq/11 signaling pathway and ATP-sensitive potassium channel ( KATP channel ) on ischemic preconditioning (IPC) protection in rat hearts. Methods Two series of experiments were performed in Wistar rat hearts. In the first series of experiment, ischemic preconditioning was induced by left anterior descending occlusion (three, 5 min episodes separated by 5 min of reperfusion), ischemia-reperfusion injury was induced by 30 min coronary artery occlusion followed by 90 min reperfusion. Hemodynamics, infarct size and scores of ventricular arrhythmias were measured. The expression of Gαq/11 protein in the heart was measured by Western blot analysis in the second series. Results Ischemic preconditioning rats showed decreased infarct size and scores of ventricular arrhythmia vs non-IP control rats. The effect of IPC was significantly attenuated by glibenclamide (1 mg/kg, ip), a nonselective KATP channel inhibitor. IPC caused a significant increase in the expression of Gαq/11 protein. Conclusions Activations of Gαq/11 signal pathway and KATP channel played significant roles in the classical cardioprotection of ischemic precon-ditioning rat heart and might be an important mechanism of signal transduction pathway during the ischemic preconditioning.

Adenosine triphosphate-sensitive potassium channel opener protects PC12 cells against hypoxia-induced apoptosis through PI3K/Akt and Bcl-2 signaling pathways

Although previous studies have shown the neuroprotective effects of the adenosine triphosphate （ATP）-sensitive potassium （KATP） channel opener against ischemic neuronal damage, little is known about the mechanisms involved. Phosphatidylinositol-3 kinase （PI3K）/v-akt murine thy-moma viral oncogene homolog （Akt） and Bcl-2 are thought to be important factors that mediate neuroprotection. The present study investigated the effects of KATP openers on hypoxia-induced PC12 cell apoptosis, as well as mRNA and protein expression of Akt and Bcl-2. Results demon-strated that pretreatment of PC12 cells with pinacidil, a KATP opener, resulted in decreased PC12 cell apoptosis following hypoxia, as detected by Annexin-V fluorescein isothiocyanate/ propidium iodide double staining flow cytometry. In addition, mRNA and protein expression of phosphorylated Akt （p-Akt） and Bcl-2 increased, as detected by immunofluorescence, Western blot analysis, and reverse-transcription polymerase chain reaction. The protective effect of this preconditioning was attenuated by glipizide, a selective KATP blocker. These results demonstrate for the first time that the protective mechanisms of KATP openers on PC12 cell apoptosis following hypoxia could result from activation of the PI3K/Akt signaling pathway, which further activates expression of the downstream Bcl-2 gene.

K_(ATP)开放剂埃他卡林对高K^+刺激PC12细胞释放谷氨酸的影响

目的 :研究KATP 开放剂埃他卡林 (iptkalim ,IPT)对高K+ 刺激PC12释放谷氨酸 (Glu)的影响及其作用机制。方法 :以培养的PC12细胞为模型细胞 ,应用HPLC法测定细胞培养液中Glu含量。结果 :IPT以浓度依赖方式抑制高K+ 刺激PC12细胞释放Glu ,格列苯脲 (Gli)增强高K+ 刺激PC12细胞释放Glu的效应 ,并部分逆转IPT的抑制效应。PKC抑制剂HA 10 0和钙调素 (CaM )拮抗剂三氟拉嗪不影响高K+ 刺激PC12细胞释放Glu ,也不拮抗Gli的增强效应。结论 :IPT抑制Glu释放与开放KATP 有关 ,Gli拮抗IPT的抑制效应并非由PKC或CaM信号传导途径介导。

前列腺素E_1对豚鼠心室肌细胞ATP敏感K^+通道的影响

目的 从离子通道水平 ,探讨前列腺素E1(PGE1)对ATP敏感K+ (KATP)通道的作用。方法 膜片钳制技术全细胞记录模式。结果 PGE1可诱导KATP通道开放并呈浓度依赖关系。保持电位 - 40mV ,指令电位 +2 0mV ,持续时间 1s条件下 ,10 μmol·L-1PGE1使外向K+ 电流由给药前的 (2 2 7± 0 34 )nA增加到 (5 46± 0 34 )nA(n =6 ,P <0 0 1) ,增加了 (3 18± 0 2 3)nA。并且增加的钾电流可被KATP通道特异阻断剂Glibenclamide(10 μmol·L-1)抑制 ,抑制率是 6 3%± 7% (n =5 ,P <0 0 1)。

ATP敏感性K^+通道在海马缺氧损伤中的作用

目的研究ATP敏感性K+通道阻断剂glipizide（GLI）对缺氧后海马脑片损伤以及海马神经元[Ca(2+)]i变化的影响。方法以大鼠离体海马脑片和体外分散培养的海马神经元为标本，分别采用电生理微电极记录技术以及激光扫描共聚焦显微镜监测神经元[Ca(2+)]i的方法。结果预先用GLI（20μmol／L）灌流的海马脑片缺氧后PV持续时间较对照组显著缩短，提示其加重了海马不可逆缺氧损伤的发生；另外急性缺氧可诱导海马神经元[Ca(2+)]i迅速升高，而预先加入GLI（20μmol／L）能显著加剧[Ca(2+)]i的升高程度。结论ATP敏感性K+通道在缺氧过程中的开放对大鼠海马脑区具有重要的保护作用，它可显著降低缺氧所致神经元[Ca(2+)]i升高，提高海马脑片的抗缺氧能力。这可能是其对抗海马缺氧损伤的主要作用机制之一。

线粒体ATP敏感性钾离子通道开放剂调控冠心病大鼠心肌凋亡的功能及机制

目的:探讨线粒体ATP敏感性钾离子通道开放剂对冠心病大鼠心肌细胞凋亡的影响及机制。方法:将50只SD大鼠随机分为对照组、冠心病组及二氮嗪低、中、高剂量组,除对照组外,其余各组大鼠均用高脂饮食联合垂体后叶素构建冠心病大鼠模型,造模后二氮嗪低、中、高剂量组大鼠分别灌胃3,5,7 mg/kg的二氮嗪,每日给药1次,共14 d,对照组和冠心病组大鼠灌胃等体积的生理盐水。治疗14 d后,取各组大鼠心肌组织,苏木精-伊红(HE)染色检测心肌损伤,原位缺口末端转移酶标记法(TUNEL)检测心肌细胞凋亡,酶联免疫吸附法(ELISA)检测血清炎性细胞因子白细胞介素-1β(IL-1β)、白细胞介素-6(IL-6)、肿瘤坏死因子-α(TNF-α)浓度,蛋白免疫印迹法(Western Blot)检测心肌组织中Cleaved-Caspase 3、Bcl-2、Bax、磷酸化蛋白激酶B(p-AKT)、蛋白激酶B(AKT)、磷酸化磷脂酰肌醇-3-激酶(p-PI3K)、磷脂酰肌醇-3-激酶(PI3K)表达。结果:相比于对照组,冠心病组大鼠心肌损伤严重,血清TNF-α、IL-1β、IL-6显著增加,心肌细胞凋亡指数增加,Cleaved-Caspase 3和Bax表达增加,Bcl-2表达、PI3K和AKT磷酸化水平降低(P<0.05)。相比于冠心病组,二氮嗪低、中、高剂量组大鼠心肌损伤均有缓解,TNF-α、IL-1β、IL-6降低,心肌细胞凋亡指数降低,Cleaved-Caspase 3和Bax表达下调,Bcl-2表达、PI3K和AKT磷酸化水平增加(P<0.05)。结论:线粒体ATP敏感性钾离子通道开放剂二氮嗪可缓解冠心病大鼠心肌细胞损伤及凋亡,其机制为激活抗凋亡的PI3K/AKT信号通路。

低出生体重新生大鼠胰岛素与K^+_(ATP)通道表达的相关性研究

目的明确低出生体重(low birth weight,LBW)新生大鼠胰腺K+ATP通道表达和胰岛素表达的相关性。方法采用孕鼠全程饥饿法建立LBW新生大鼠模型,并设立对照组。于生后第一天取血和胰腺,测定血糖和胰岛素水平;应用免疫组化法检测胰岛β细胞量和胰岛素分泌,用半定量RT-PCR法检测K+ATP通道和胰岛素表达量。结果LBW组血胰岛素水平、胰腺重量和胰岛素分泌指数均低于对照组,LBW组胰岛素抵抗指数高于对照组(P均<0.05)。LBW组胰岛中胰岛素的积分吸光度以及胰岛素、K+ATP通道mRNA表达量均低于对照组(P均<0.05)。LBW组的胰岛素mRNA表达量与KATP通道mRNA表达量相关(r=0.934,P=0.007)。结论低出生体重新生大鼠生后第一天即存在胰岛素分泌缺陷和胰岛素抵抗,胰岛β细胞数量的减少,胰岛素表达减少。其胰岛素分泌缺陷可能与β细胞K+ATP通道表达减少有关。

ATP敏感性钾通道亚基突变对血管生理特性的影响

目的:探究ATP敏感性钾通道亚基突变(Kir6.1[V65M])对血管生理特性的影响。方法:以同窝野生型(WT,野生组,n=35)及杂合突变小鼠(V65M+/-,突变组,n=52)为研究对象,采用颈动脉插管测定两组小鼠的收缩压和舒张压;分离降主动脉,制成3-5mm左右动脉环,经生物信号采集与分析系统测定动脉环张力的变化;分离单个血管平滑肌细胞,利用全细胞膜片钳技术记录L型钙通道电流;眼眶内眦静脉采血,采用ELISA试剂盒检测血清肾素、血管紧张素、醛固酮表达水平。结果:与野生组小鼠相比,突变组小鼠收缩压和舒张压明显下降(P<0.01)。突变组小鼠在60mmol/L KCl及1μmol/L去甲肾上腺素刺激下的张力改变明显高于野生组小鼠(P<0.05);突变组小鼠动脉环对低浓度(0.1μmol/L)及高浓度吡那地尔(0.3μmol/L)的舒张反应性均大于野生组小鼠(P<0.01)。突变组小鼠血管平滑肌细胞钙电流峰值增加(P<0.05)。与野生组小鼠相比,突变组小鼠肾素、血管紧张素II水平升高(P<0.05)。结论:Kir6.1[V65M]突变使血压下降,反射性引起机体代偿调节,激活RAAS系统,血管平滑肌细胞钙电流增加,使得血管对收缩剂及舒张剂的张力反应性增加。

K-ATP channel openers facilitate glutamate uptake by GluTs in rat primary cultured Astrocytes

Increasing evidence, including from our laboratory, has revealed that opening of ATP sensitive potassium channels(K-ATP channels) plays the neuronal protective roles both in vivo and in vitro. Thus K-ATP channel openers(KCOs) have been proposed as potential neuroprotectants. Our previous studies demonstrated that K-ATP channels could regulate glutamate uptake activity in PC12 cells as well as in synaptosomes of rats. Since glutamate transporters(GluTs) of astrocytes play crucial roles in glutamate uptake and KATP channels are also expressed in astrocytes, the present study showed whether and how KATP channels regulated the function of GluTs in primary cultured astrocytes. The results showed that nonselective KCO pinacidil, selective mitochondrial KCO diazoxide, novel, and blood-brain barrier permeable KCO iptakalim could enhance glutamate uptake, except for the sarcolemmal KCO P1075. Moreover pinacidil, diazoxide, and iptakalim reversed the inhibition of glutamate uptake induced by 1-methyl-4-phenylpyridinium(MPP+). These potentiated effects were completely abolished by mitochondrial K-ATP blocker 5-hydroxydecanoate. Furthermore, either diazoxide or iptakalim could inhibit MPP+-induced elevation of reactive oxygen species (ROS) and phosphorylation of protein kinases C(PKC). These findings are the first to demonstrate that activation of K-ATP channel, especially mitochondrial K-ATP channel, improves the function of GluTs in astrocytes due to reducing ROS production and downregulating PKC phosphorylation. Therefore, the present study not only reveals a novel pharmacological profile of KCOs as regulators of GluTs, but also provides a new strategy for neuroprotection.

Activation of SUR2B/Kir6.1-type K ATP channels protects glomerular endothelial,mesangial and tubular epithelial cells against oleic acid renal damage

Cumulative evidence suggests that renal vascular endothelial injury play an important role in initiating and extending tubular epithelial injury and contribute to the development of ischemic acute renal failure.Our previous studies have demonstrated that iptakalim's endothelium protection is related to activation of SUR2B/Kir6.1 subtype of ATP sensitive potassium channel(K ATP) in the endothelium.It has been reported that SUR2B/Kir6.1 channels are widely distributed in the tubular epithelium,glomerular mesangium,and the endothelium and the smooth muscle of blood vessels.Herein,we hypothesized that activating renal K ATP channels with iptakalim might have directly neroprotective effects.In this study,glomerular endothelial,mesangial and tubular epithelial cells which are the main cell types to form nephron were exposed to oleic acid(OA) at various concentrations for 24 h.0.25 μl/ml OA could cause cellular damage of glomerular endothelium and mesangium,while 1.25μl/ml OA could lead to the injury of three types of renal cells.It was observed that pretreatment with iptakalim at concentrations of 0.1,1,10 or 100 μmol/L prevented cellular damage of glomerular endothelium and tubular epithelium,whereas iptakalim from 1 to 100 μmol/L prevented the injury of mesangial cells.Our data showed iptakalim significantly increased survived cell rates in a concentration-dependent manner,significantly antagonized by glibenclamide,a K ATP blocker.Iptakalim played a protective role in the main cell types of kidney,which was consistent with natakalim,a highly selective SUR2B/Kir6.1 channel opener.Iptakalim exerted protective effects through activating SUR2B/Kir6.1 channels,suggesting a new strategy for renal injury by its endothelial and renal cell protection.

硫化氢通过激活ATP敏感性钾通道保护小鼠在体缺血损伤视网膜和原代缺氧视网膜神经节细胞

目的:研究硫化氢(H_2S)是否能够通过激活ATP敏感性钾通道(K_(ATP)通道)减轻小鼠原代缺氧视网膜神经节细胞及在体缺血视网膜损伤。方法:(1)培养分离纯化的小鼠原代视网膜神经节细胞(RGCs),给予缺氧处理或缺氧+硫氢化钠(NaHS)处理,利用Hoechst 33258染色和ELISA测定培养液中乳酸脱氢酶(LDH)浓度观察细胞死亡率变化;给予K_(ATP)通道激动剂或阻断剂,利用膜片钳、Western blot和钙成像技术观察硫化氢是否通过K_(ATP)通道减轻缺氧导致的细胞损伤;(2)在体建立小鼠视网膜缺血模型,模型动物分为5组(每组8只小鼠),分别为溶剂对照组、NaHS组、NaHS+K_(ATP)通道阻断剂组、K_(ATP)通道激动剂组和K_(ATP)通道激动剂+K_(ATP)通道断剂组,组织学切片观察视网膜各层厚度及RGCs层细胞密度变化。结果:(1)与氧糖剥夺(OGD)组相比,100μmol/L和300μmol/L NaHS可以显著减轻缺氧导致的原代RGCs细胞死亡率(P<0.01),同时也减少LDH释放量(1.5±0.3和1.3±0.2, P<0.01);与OGD组相比,NaHS和K_(ATP)通道激动剂可使细胞显著超极化(P<0.05, n=26),诱发放电显著减少(P<0.01, n=29),显著减少钙内流(P<0.01, n=14)和cleaved caspase-3表达量(P<0.05, n=7),显著减轻氧糖剥夺导致的原代RGCs损伤;而K_(ATP)通道阻断剂使细胞去极化,诱发放电增多,增加钙离子内流和cleaved caspase-3表达,逆转了这种保护作用;(2)在体实验中,给予NaHS或K_(ATP)通道激动剂可以显著逆转缺血损伤导致的视网膜厚度降低(P<0.05,n=8);与缺血组比较,RGCs层细胞密度也显著增高(P<0.05, n=8),而K_(ATP)通道阻断剂能够抑制这种保护作用。结论:NaHS可通过激活K_(ATP)通道减轻原代缺氧小鼠RGCs和小鼠在体缺血视网膜导致的损伤。

线粒体ATP敏感钾通道与线粒体自噬对心力衰竭的作用研究

心力衰竭是由心脏的收缩和/或舒张功能发生障碍,导致心室泵血功能受损引起的循环障碍症候群。临床主要表现为呼吸困难、咳嗽和咳痰。心力衰竭是心脏疾病发展的终末阶段,患者预后较差,目前心力衰竭的发病机制尚不完全明确。近年来,许多研究表明线粒体功能障碍与心力衰竭的发生发展密切相关。现对线粒体ATP敏感钾通道以及线粒体自噬对心力衰竭的作用进展进行综述。

ATP敏感性钾通道与缺血性脑卒中关系的研究进展

缺血性脑卒中(CIS)是一种具有高致残率及高病死率特征的神经系统疾病。脑组织的快速缺血缺氧会破坏神经元、胶质细胞和内皮细胞的能量依赖过程(如跨膜离子梯度和细胞稳态),引发一系列神经损伤病理反应,如神经血管单元的破坏、突触结构与功能的破坏、兴奋性氨基酸毒性作用、炎症反应、细胞自噬、细胞凋亡、细胞焦亡等。研究发现ATP敏感性钾通道(KATP)在脑中广泛分布,且通道的开放和关闭状态会对CIS产生不同的影响,本文对KATP通道与CIS的关系进行总结,以期为CIS的进一步研究及临床治疗提供参考。