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.

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.

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.

Hydrogen sulfide attenuates gastric mucosal injury induced by restraint water-immersion stress via activation of KATPchannel and NF-κB dependent pathway

AIM To explore the effect of hydrogen sulfide(H2S)on restraint water-immersion stress(RWIS)-induced gastric lesions in rats and the influence of adenosine triphosphate(ATP)-sensitive potassium(KATP)channels and nuclear factor kappa-light-chain-enhancer of activated B cells(NF-κB)pathway on such an effect.METHODS Male Wistar rats were randomly divided into a control group,a physiological saline(PS)group,a sodium hydrosulfide(Na HS)group,a glibenclamide(Gl)group,Gl plus Na HS group,a pyrrolidine dithiocarbamate(PDTC)group,and a PDTC plus Na HS group.Gastric mucosal injury was induced by RWIS for 3 h in rats,and gastric mucosal damage was analyzed after that.The PS,Na HS(100μmol/kg body weight),Gl(100μmol/kg body weight),Gl(100μmol/kg or 150μmol/kg body weight)plus Na HS(100μmol/kg body weight),PDTC(100μmol/kg body weight),and PDTC(100μmol/kg body weight)plus Na HS(100μmol/kg bodyweight)were respectively injected intravenously before RWIS.RESULTS RWIS induced serious gastric lesions in the rats in the PS pretreatment group.The pretreatment of Na HS(a H2S donor)significantly reduced the damage induced by RWIS.The gastric protective effect of the Na HS during RWIS was attenuated by PDTC,an NF-κB inhibitor,and also by glibenclamide,an ATP-sensitive potassium channel blocker,in a dose-dependent manner.CONCLUSION These results suggest that exogenous H2S plays a protective role against RWIS injury in rats,possibly through modulation of KATP channel opening and the NF-κB dependent pathway.

Iptakalim,an ATP-sensitive potassium channel opener,confers neuroprotection against cerebral ischemia/reperfusion injury in rats by protecting neurovascular unit cells

Objective:To investigate the role of iptakalim,an ATP-sensitive potassium channel opener,in transient cerebral ischemia/reperfusion (I/R) injury and its involved mechanisms.Methods:Intraluminal occlusion of middle cerebral artery (MCAO) in a rat model was used to investigate the effect of iptakalim at different time points.Infarct volume was measured by staining with 2,3,5-triphenyltetrazolium chloride,and immunohistochemistry was used to evaluate the expressions of Bcl-2 and Bax.In vitro,neurovascular unit (NVU) cells,including rat primary cortical neurons,astrocytes,and cerebral microvascular endothelial cells,were cultured and underwent oxygen-glucose deprivation (OGD).The protective effect of iptakalim on NVU cells was investigated by cell viability and injury assessments,which were measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and release of lactate dehydrogenase.Caspase-3,Bcl-2 and Bax mRNA expressions were evaluated by real-time polymerase chain reaction (PCR).Results:Administration of iptakalim 0 or 1 h after reperfusion significantly reduced infarct volumes,improved neurological scores,and attenuated brain edema after cerebral I/R injury.Iptakalim treatment (0 h after reperfusion) also reduced caspase-3 expression and increased the ratio of Bcl-2 to Bax by immunohistochemistry.Iptakalim inhibited OGD-induced cell death in cultured neurons and astrocytes,and lactate dehydrogenase release from cerebral microvascular endothelial cells.Iptakalim reduced mRNA expression of caspase-3 and increased the ratio of Bcl-2 to Bax in NVU cells.Conclusions:Iptakalim confers neuroprotection against cerebral I/R injury by protecting NVU cells via inhibiting of apoptosis.

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.

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。

二氮嗪在长时程心脏低温保存中的作用

延长心脏的体外有效保存时间对临床心脏移植具有重要意义。本文旨在研究线粒体ATP 敏感性钾通道开放剂二氮嗪(diazoxide, DE)在离体大鼠心脏长时程低温保存中的作用。SD 大鼠随机分成 5 组,包括对照组(单纯 Celsior 保存液), DE 组(Celsior 液中含 15、30 或 45 μmol/L 的 DE)和 DE+5-HD 组 [Celsior 液中含 30 μmol/L 的 DE 和 100 μmol/L 的 5- 羟基葵酸盐(5-hydroxydecanoate, 5-HD)]。利用 Langendorff 离体鼠心灌注法, 观察心脏在 4℃条件下保存 10 h 后, 复灌期血流动力学恢复、冠脉流出液中心肌酶漏出量及心肌水含量变化, 并做心肌超微结构检查。结果显示:与对照组比较,DE 处理后,复灌期的左心室舒张末期压力明显降低,心率、左心室发展压、左心室压力变化率、冠脉流出量等的恢复率在多个复灌时间点上优于对照组,且能显著减少复灌过程中心肌酶(乳酸脱氢酶、磷酸肌酸激酶及谷草转氨酶)的漏出量,降低心肌水含量;其中30 和45 μmol/L DE 组的保护作用优于15 μmol/L DE 组;电镜结果显示DE 对长时程低温保存心脏的超微结构有较好的保护作用。DE 的上述作用可被线粒体ATP 敏感性钾通道的特异性阻断剂 5-HD 所取消。以上结果提示:DE 可通过激活线粒体 ATP 敏感性钾通道显著改善离体大鼠心脏长时程低?

线粒体ATP敏感性钾通道开放剂改善大鼠心脏冷保存

目的:探讨线粒体ATP敏感性钾通道开放剂二氮嗪(DE)对离体大鼠心脏冷保存效果的影响及作用机制。方法:SD大鼠随机分成对照组、DE组、DE+5-HD组。利用Langendorff离体鼠心灌注法,各组心脏在4℃条件下分别保存3h和8h后,复灌60min,观察各组大鼠血流动力学的恢复情况、冠脉流出液中心肌酶漏出量、心肌水含量的变化及心肌超微结构改变。结果:在Celsior心麻痹液中添加30μmol/L的DE后,能明显改善冷保存3h心脏的左心室发展压力的恢复,降低心肌酶(LDH、CK)在某些复灌时间点上的漏出,但对保存后左心室舒张末期压力的抬高和冠脉流量的恢复及心肌水肿程度无明显作用;而相同浓度的DE添加到Celsior心麻痹液中,可明显降低冷保存8h心脏左心室舒张末期压力的抬高,改善左心室发展压力和冠脉流量的恢复,降低心肌酶(LDH、CK、GOT)的漏出,缓解心肌水肿,对心肌的超微结构也有较好的保护作用,其中30和45μmol/LDE组对冷保存8h心脏的保护作用优于15μmol/LDE组,而30及45μmol/LDE组之间并无显著性差异。DE的上述作用可被线粒体ATP敏感性钾通道的特异性阻断剂5-HD所取消。结论:DE可通过激活线粒体ATP敏感性钾通道显著改善离体大鼠心脏冷保存效果。

ATP敏感性钾通道开放剂埃他卡林对大鼠低氧性肺动脉高压的影响

目的 :探讨新型ATP敏感性钾通道开放剂 (KATPCO)埃他卡林 (iptkalim ,Ipt)对低氧性肺动脉高压 (HPH)大鼠肺血管重构的影响。方法 :将大鼠置于常压低氧舱内 (O2 1 0 %± 0 .5 % ) ,8h/d ,每周 6d ,4周后测定平均肺动脉压(mPAP)、RV/ (LV +S) ;用图象分析仪测量与呼吸性细支气管伴行的肺小动脉外径 (ED)、动脉中层壁厚 (MT)、动脉管壁中层面积 (MA)、动脉管腔面积 (VA)和血管总面积 (TAA)。结果 :慢性低氧组大鼠的mPAP和RV/ (LV +S)显著高于正常对照组 (P <0 .0 1 ) ;图象分析显示低氧组大鼠肺小动脉中层壁厚与动脉外径百分比 (MT % )、动脉壁中层面积与血管总面积百分比 (MA % )均显著高于对照组 (P <0 .0 1 ) ;慢性低氧组大鼠肺小动脉管腔面积 (VA)与血管总面积 (TAA)百分比显著低于正常组 (P <0 .0 1 )。Ipt 0 .75mg·kg- 1 ·d- 1 和 1 .50mg·kg- 1 ·d- 1 均可显著抑制低氧性肺血管壁重构 ,降低肺动脉压 ,减少右心室肥厚 ,1 .50mg·kg- 1 ·d- 1 则可逆转持续低氧所致的所有病理性变化。结论

ATP敏感性钾通道及其心血管保护作用

ATP-sensitive potassium channel(KATP) consists of a 4.4 complex of an inwardly rectifying Kir6.x pore plus a sulfonylurea receptor,which is an ATP-binding cassette transporter.KATP has been indentified in a variety of tissues and recognized as an important drug target.It connects cell metabolism with cell electric activity.KATP has been proposed to play protective roles during heart failure,arrhythmia,myocardial infarction,stress,myocardial ischemia and hypertension.In this review,a summary of KATP is presented with molecular structure,localization,regulation,cardiovascular protective effect and its mechanisms.

线粒体三磷酸腺苷敏感性钾通道在未成熟心肌缺血预处理中的作用

目的探讨线粒体三磷酸腺苷敏感性钾通道（mitoKATP）在未成熟心肌预处理保护中的作用，为未成熟心肌的保护提供依据。方法采用Langendorff离体心脏灌注模型，将24只新生（出生14～21d）日本长耳大白兔按随机数字表法分为4组：缺血／再灌注组（I／R组），心脏缺血预处理组（E1组），mitoKATP阻滞剂5-hydroxydecanoate（5-HD）＋心脏缺血预处理（E2组），mitoKATP通道开放剂Diazoxide（Diaz）预处理组（E3组）；检测心脏功能恢复率、心肌含水量、血清肌酸激酶和乳酸脱氢酶漏出率、三磷酸腺苷（ATP）含量、超氧化物歧化酶活性、丙二醛含量、心肌细胞内Ca^2＋含量、心肌线粒体Ca^2＋含量、心肌线粒体Ca^2＋-三磷酸腺苷酶活性（Ca^2＋-ATPase）、心肌线粒体合成ATP的能力；电子显微镜观察心肌超微结构。结果E1组、E3组心功能恢复优于I／R组和E2组，心肌含水量低于I／R组和E2组（P〈0．05）；E1组、E3组三磷酸腺苷含量、超氧化物歧化酶活性、心肌线粒体Ca^2＋-ATPase活性、心肌线粒体合成ATP的能力均优于I／R组和E2组（P〈0．05），丙二醛含量、血清肌酸激酶和乳酸脱氢酶漏出率、心肌细胞内Ca^2＋含量、心肌线粒体Ca^2＋含量低于I／R组、E2组（P〈0．05）；E1组、E3组心肌超微结构损伤较I／R组和E2组明显减轻。结论心肌缺血预处理对未成熟心肌具有明显的保护作用，其机制可能是通过mitoKATP通道的开放起作用。

盐酸埃他卡林扩血管特征的研究

目的 观察新型抗高血压药盐酸埃他卡林对大、小动脉扩张作用的药理学特征。方法 采用大鼠主动脉离体血管环和尾动脉螺旋状血管条两种组织来对比分析盐酸埃他卡林的扩血管作用。结果 盐酸埃他卡林在 10 -7～ 10 -3 mol/L范围内对氯化钾预致收缩的大鼠尾动脉血管条产生剂量依赖性舒张反应 ,且具有部分内皮依赖性 ,但对主动脉离体血管环无明显的舒张反应 ,该作用在高血压状态时显著增强 ,能被ATP敏感性钾通道特异性阻断剂格列苯脲阻断。结论 盐酸埃他卡林具有选择性舒张小动脉的作用 ,该作用与其激活ATP敏感性钾通道有关。

七氟醚预处理对全身缺氧损伤小鼠的保护作用

目的观察七氟醚（Sev）预处理对小鼠全身缺氧损伤的保护作用。方法 6~7周龄健康雄性昆明小鼠180只随机分为Sev 0.5 h组、Sev 24 h组、Sev 0.5 h＋格列本脲（Gli）组、Sev 24 h＋Gli组及对照组（P组）5组,每组36只。Sev 0.5 h组小鼠吸入体积分数1.0%Sev 30 min,在空气中洗脱30 min后放入体积分数5%O2＋95%N2环境中持续20 min;Sev 24 h组小鼠每天吸入体积分数1.0%Sev 30 min,连续2 d,第3天放入体积分数5%O2＋95%N2环境中;Sev 0.5 h＋Gli组和Sev 24 h＋Gli组小鼠分别在吸入Sev前30 min腹腔注射Gli 6 mg·kg-1;P组小鼠不吸入Sev,直接放入体积分数5%O2＋95%N2环境中。预处理后洗脱30 min,观察小鼠在体积分数5%O2环境中20 min内的生存时间、生存率及复氧24 h后脑、心、肺组织含水量和海马CA、皮层区坏死及变性细胞病理量化评分。结果与P组比较,Sev 0.5 h组和Sev 0.5 h＋Gli组小鼠生存率提高、生存时间延长（P〈0.05）,而Sev 24 h组和Sev 24 h＋Gli组差异无统计学意义（P〉0.05）。Sev 0.5 h组与Sev 24 h组比较,小鼠生存率显著增高,生存时间显著延长（P〈0.05）。Sev 0.5 h＋Gli组较Sev 0.5 h组小鼠生存时间显著延长,生存率显著增高（P〈0.05）。Sev 24 h组和Sev24 h＋Gli组比较差异无统计学意义（P〉0.05）。各组小鼠组织含水量和脑组织病理量化评分比较差异无统计学意义（P〉0.05）。结论 Sev预处理对全身缺氧损伤小鼠有保护作用,通过即刻效应提高小鼠在低氧环境中的生存率,延长其生存时间;ATP敏感性钾通道阻断剂Gli不能阻断其保护效应。

埃他卡林等三种结构类型的钾通道开放剂对非血管平滑肌舒张作用的选择性

目的:研究新结构类型的ATP敏感性钾通道(KATP)开放剂(KCO)、抗高血压新药埃他卡林(iptakalim,Ipt)对胃、回肠和膀胱等非血管平滑肌舒张作用的影响,并比较Ipt与其结构完全不同的KCO、氰胍类的吡那地尔(pinacidil,Pin)和苯并噻二嗪类的二氮嗪(diazoxide,Dia)舒张作用的差异,为进一步明确Ipt舒张作用的选择性特征提供一定的依据。方法:采用大鼠离体胃底、回肠和膀胱肌条3种组织,以10-5mol·L-1乙酰胆碱预收缩,观察不同浓度的药物对它们的舒张作用。结果:Ipt在10-8～10-4mol·L-1范围内对3种组织均无显著的舒张作用;Pin在10-8～10-4mol·L-1范围内对胃底条和膀胱平滑肌等均无显著的舒张作用,但在10-5和10-4mol·L-1时对回肠的舒张率分为28.8%和51.9%,诱发显著的舒张作用;Dia对3种组织的作用与Ipt相似,均不引起明显的舒张作用。结论:Ipt不影响胃、回肠和膀胱的舒张作用,选择性优于Pin,与Dia相似;化学结构类型不同的KCO对回肠、胃和膀胱的作用既相似也有不同。

急性心肌缺血与ST段抬高

ST段抬高可见于许多临床病理情况,是冠心病急性心肌缺血进行急诊血运重建的主要标准。目前,ST段抬高的具体分子机制尚未完全明确。现就急性心肌缺血时ST段抬高的可能机制作一综述。

三磷酸腺苷敏感性钾离子通道在外源性硫化氢抑制高糖诱导的成骨细胞损伤中的作用

目的研究三磷酸腺苷敏感性钾离子通道(KATP)在硫化氢(H2S)抑制高糖(HG)诱导的成骨细胞损伤中的作用。方法原代培养大鼠下颌骨成骨细胞并鉴定,将成骨细胞给予HG、H2S、KATP通道开放剂吡拉地尔(Pia)、阻断剂格列本脲(Gli)处理后,用Western blot检测KATP通道蛋白的表达水平,同时采用CCK8、实时逆转录聚合酶链反应(RT-PCR)、茜素红S染色分析方法检测其对成骨细胞增殖、分化及矿化的影响。结果细胞KATP通道蛋白的表达水平在HG的影响下明显降低,H2S预处理明显抑制HG对KATP通道蛋白的下调作用和对成骨细胞增殖的影响,并防止HG引起的成骨细胞分化和矿化的减少;相反,KATP通道阻断剂能明显阻断H2S对成骨细胞的上述保护作用。结论 H2S通过KATP通道抑制了HG诱导的成骨细胞损伤。

三磷酸腺苷后处理通过RISK信号通路和mKATP减轻兔心肌缺血再灌注损伤

目的探讨再灌注损伤挽救激酶(RISK)信号通路和线粒体ATP敏感性钾通道(mKATP)在三磷酸腺苷(ATP)后处理减轻兔心肌缺血再灌注损伤中的作用。方法选择60只雄性大耳白兔随机为缺血再灌注损伤组(IRI组)、ATP后处理组、PI3K抑制剂Wortmannin+ATP后处理组(Wortmannin+ATP组)、ERK1/2抑制剂PD98059+ATP后处理组(PD98059+ATP组)、选择性mKATP抑制剂5-HD+ATP后处理组(5-HD+ATP组),每组12只,建立心肌缺血再灌注模型。采用依文思蓝和四氮唑蓝双重染色测定心肌梗死面积,TUNEL法检测心肌细胞凋亡,Western blot检测心肌Akt、p-Akt、ERK1/2及p-ERK1/2蛋白的表达。结果 ATP后处理组心肌梗死面积、心肌细胞凋亡指数明显低于IRI组(P<0.01)。Wortmannin+ATP组、PD98059+ATP组和5-HD+ATP后处理组心肌梗死面积、心肌细胞凋亡指数与IRI组比较差异无统计学意义。Western blot检测显示,ATP后处理组p-Akt、p-ERK1/2表达水平明显高于IRI组(P<0.05)。结论 ATP后处理可通过缩小心肌梗死面积和减少心肌细胞凋亡发挥对缺血再灌注心肌的保护作用,其机制可能与RISK信号通路及mKATP有关。

海马脑片缺氧早期腺苷的作用及其机制研究

本实验采用海马脑片细胞外记录技术，观察了缺氧早期突触功能可逆性抑制中腺苷的作用并初步探讨其作用机制。结果发现：海马脑片缺氧早期突触功能出现可逆性抑制，与外源施加高浓度腺苷反应类同。腺苷Ａ１受体拮抗剂ＣＰＴ以及Ｋ＋通道阻断剂４－ＡＰ可阻断这种抑制作用；而ＴＥＡ以及ＡＴＰ敏感Ｋ＋通道阻断剂ｇｌｉｐｉｚｉｄｅ均未见显著效应。结果提示：缺氧早期突触功能可逆性抑制与内源性腺苷大量释放有关，腺苷通过作用其Ａ１受体，激活４－ＡＰ敏感Ｋ＋通道，从而抑制突触传递，显示其抗缺氧作用。ＡＴＰ敏感性Ｋ＋通道可能不参于这个过程。

2例新生儿糖尿病患者致病基因型及疗效分析

目的分析2例新生儿糖尿病患者的致病基因型及探讨格列苯脲的疗效。方法选取2013年4月至2014年10月本院收治并确诊的新生儿糖尿病患儿2例,对其进行常见致病基因KCNJ11、ABCC8、INS和GCK 4个基因测序分析,并复习相关文献,根据基因结果给予硫脲类药物试验性治疗。结果病例1的KCNJ11基因检测到3个杂合突变,其中Arg201His为已报道的永久性新生儿糖尿病致病突变,余2个位点为无致病性的单核苷酸多态性,ABCC8、INS和GCK基因检测未发现突变;病例2的KCNJ11基因检测到2个杂合突变,位点与病例1非致病性突变位点相同,余基因测序未发现异常。给予病例1格列苯脲口服疗效满意,胰岛素减停后随访血糖平稳;给予病例2格列苯脲试验性用药,疗效不佳。结论新生儿糖尿病的遗传发病机制复杂,KCNJ11基因突变可导致新生儿糖尿病的发生,格列苯脲适于用治疗KCNJ11基因突变阳性病例。