Objective This review focuses on the role of the large conductance calcium-activated potassium （BKCa） channels in diabetic vascular complications.Data sources Relevant articles published in English or Chinese from 1...Objective This review focuses on the role of the large conductance calcium-activated potassium （BKCa） channels in diabetic vascular complications.Data sources Relevant articles published in English or Chinese from 1981 to present were selected from PubMed.The search terms were ＂BKCa channels＂ and ＂diabetes＂.Important references from selected articles were also retrieved.Study selection Articles regarding the role of BKCa channels in diabetic vascular complications and relevant mechanisms were selected.Results The BKCa channels are abundantly expressed in vascular smooth cells and play an important role in regulation of vascular tone.Multiple studies indicated that the expression and function of BKCa channels are altered by different mechanisms in diabetic vascular diseases such as coronary arterial disease,cerebral arterial disease,and diabetic retinopathy.Conclusion BKCa channels may play an important role in diabetic vascular complications and may be an effective therapeutic target for relieving and reducing the burden of diabetic vascular complications.展开更多
Increasing evidence suggests that low to mod- erate ethanol ingestion protects against the deleterious effects of subsequent ischemia/reperfusion; however, the underlying mechanism has not been elucidated. In the pres...Increasing evidence suggests that low to mod- erate ethanol ingestion protects against the deleterious effects of subsequent ischemia/reperfusion; however, the underlying mechanism has not been elucidated. In the present study, we showed that expression of the neuronal large-conductance, Ca2＋-activated K＋ channel （BKca） α- subunit was upregulated in cultured neurons exposed to oxygen-glucose deprivation/reoxygenation （OGD/R） compared with controls. Preconditioning with low-dose ethanol （10 mmol/L） increased cell survival rate in neurons subjected to OGD/R, attenuated the OGD/R-induced elevation of cytosolic Ca2＋ levels, and reduced the number of apoptotic neurons. Western blots revealed that ethanol preconditioning upregulated expression of the anti-apoptotic protein Bcl-2 and downregulated the pro-apoptotic protein Bax. The protective effect of ethanol precondi- tioning was antagonized by a BKα channel inhibitor, paxilline. Inside-out patches in primary neurons also demonstrated the direct activation of the BKCa channel by 10 mmol/L ethanol. The above results indicated that low- dose ethanol preconditioning exerts its neuroprotective effects by attenuating the elevation of cytosolic Ca2＋ and preventing neuronal apoptosis, and this is mediated by BKca channel activation.展开更多
Some drugs exert curative effects intracellu- larly, but their hydrophilic property prohibits the mem- brane-penetrating process and thus limits the curative efficacies, although this property guarantee their solubili...Some drugs exert curative effects intracellu- larly, but their hydrophilic property prohibits the mem- brane-penetrating process and thus limits the curative efficacies, although this property guarantee their solubility in aqueous phase. An example is sodium tanshinone II-A sulfonate （DS-201）, a derivative of Chinese medical herb Danshen （Salvia miltiorrhiza） which is a BKc~ channel opener and a vasodilator. This study established and opti- mized a liposome delivery system which could pack and deliver DS-201 into HEK293 cells transfected with BKca channels, and DS-201 given this way significantly increased the open probability of BKca channel from baseline 0.013 ~ 0.004 to 0.036 -4- 0.011 at -t-40 mV membrane potential （P 〈 0.05） in single-channel attached study, and also increased the current density from baseline 23.2 ＋ 4.4 to 66.0 4- 15.2 pA/pF at ＋40 mV membrane potential （P 〈 0.05）, compared with the direct extracellular administration of this drug. Moreover, showing a ~ 60 % inhibition of the PE or PGF2a induced vascular constric- tion, the DS-201 liposomes did posses significantly enhanced vasorelaxant effect on rat mesenteric artery, compared with 20 % inhibition of the directly administration of this drug （P 〈 0.05）, suggesting that DS-201 delivered by liposomes significantly improved the drug＇s vasorelaxing effect. Taken together, the optimized DS-201 liposomes in our study successfully delivered DS-201 into cells and thus significantly activated BKca channels to reverse the contraction induced by PE and PGF2a, attesting the enhanced bioavailability.展开更多
目的:研究茜草素对Wistar大鼠肾叶间动脉及其平滑肌细胞大电导钙激活钾通道(Large Conductance Calcium Activated Potassium Channels;BKCa)的影响。方法:压力型小动脉测量仪用于观察给予茜草素前后肾叶间动脉血管直径的变化;全细胞膜...目的:研究茜草素对Wistar大鼠肾叶间动脉及其平滑肌细胞大电导钙激活钾通道(Large Conductance Calcium Activated Potassium Channels;BKCa)的影响。方法:压力型小动脉测量仪用于观察给予茜草素前后肾叶间动脉血管直径的变化;全细胞膜片钳技术用于研究茜草素对离体的Wistar大鼠肾叶间动脉平滑肌细胞BKCa介导的外向电流的调节作用。结果:(1)茜草素(10^(-7)~3×10^(-5)mol/L)舒张肾叶间动脉(P<0.01);(2)茜草素(10^(-7)~3×10^(-5)mol/L)增强Wistar大鼠肾叶间动脉平滑肌细胞外向电流(60 m V)呈浓度依赖性(P<0.05);(3)在0 m V^60 m V,茜草素(10-5mol/L)增强Wistar大鼠肾叶间动脉平滑肌细胞外向电流呈电压依赖性(P<0.05);(4)TEA(10-4mol/L)阻断茜草素(10-5mol/L)增强的肾叶间动脉平滑肌细胞外向电流(60 m V)(P<0.01);(5)10^(-7)mol/L的BKCa阻断剂伊比利亚毒素(ib TX)阻断茜草素(10^(-5)mol/L)对肾叶间动脉平滑肌细胞外向电流(60 m V)的增强作用(P<0.01)。结论:茜草素通过激活更多BKCa开放促进钾离子外流,引起Wistar大鼠肾叶间动脉平滑肌细胞超极化,舒张肾叶间动脉血管。展开更多
There is accumulating evidence that the subfamily of large-conductance potassium (“big”, “BK”) channels are involved in diverse, and perhaps coordinated, protective or counteractive responses to local or generaliz...There is accumulating evidence that the subfamily of large-conductance potassium (“big”, “BK”) channels are involved in diverse, and perhaps coordinated, protective or counteractive responses to local or generalized ischemia and hypoxia. Although widely distributed, the physiological differences among BK channels which results from posttranslational modification (alternative splicing) and co-assembly with auxiliary modulatory subunits (<em>β</em><sub>1-4</sub> and <em>γ</em><sub>1-4</sub>), bestows localized differences in subunit composition, distribution, 2<sup>nd</sup>-messenger coupling, and pharmacologic properties. Due to the ubiquitous nature of BK channels and the multiplicity of subtypes, they have many potential therapeutic applications in the maintenance of oxygen homeostasis, cerebro- and cardio-protection, and stimulation of respiration in response to drug-induced respiratory depression. BK channels may also offer other potentially broad and underrecognized promising targets for novel pharmaceutical development.展开更多
Large conductance Ca^(2+)-activated K^+ (BK_(Ca)) channel exhibits a phenotype-dependent expression on vascular smooth muscle cells(VSMCs), which prefers to contractile phenotype. Meanwhile, shear stress definitely in...Large conductance Ca^(2+)-activated K^+ (BK_(Ca)) channel exhibits a phenotype-dependent expression on vascular smooth muscle cells(VSMCs), which prefers to contractile phenotype. Meanwhile, shear stress definitely influences VSMCs proliferation and contraction. Thereby, a hypothesis was raised, would shear stress change the BK_(Ca)expression and correlate with VSMC phenotype? In order to investigate it, VSMCs were exposed to shear stress in a parallel-plate flow chamber with 12 dynes/cm^2 for 12 h. Subsequently, the effect of shear stress on VSMC proliferation, BK_(Ca)channel expression and contractile phenotype marker, α-smooth muscle cell actin(α-SMA) and smooth muscle myosin heavy chain(SMMHC), was determined by immunofluorescence microscopy, flow cytometery as well as reverse transcriptionpolymerase chain reaction(RT-PCR), respectively. Data show that shear stress enhanced the expression of BK_(Ca)channel while inhibiting VSMC proliferation.Paralleled to those phenomena, the expression of both α-SMA and SM-MHC were decreased significantly. These results demonstrated that upregulation of BK_(Ca)channel was irrelevant to the maintenance VSMC of contractile phenotype under shear stress.This finding provides a new insight into understanding the correlation of BK_(Ca)channel and VSMC phenotype.展开更多
OBJCETIVE Epidemiologic studies have demonstrated that consumption of moderate amounts of red wine is associated with significant reductions in incidences of cardiovascular and cerebrovascular diseases,which may be re...OBJCETIVE Epidemiologic studies have demonstrated that consumption of moderate amounts of red wine is associated with significant reductions in incidences of cardiovascular and cerebrovascular diseases,which may be related to alcohol in red wine.Our previous study demonstrated that ethanol ingestion 24 h prior to induction of cerebral ischemic/reperfusion(I/R)reduced delayed neuronal death(DND).Our most recent results supported a role for big Ca2+-sensitive K+channel(BKCa channel)activation in the neuroprotective effects of ethanol preconditioning(Et OH-PC)in global cerebral I/R.Therefore,we hypothesis that moderate Et OH-PC activates BKCa channel to protect brain damage induced by focal cerebral I/R.This project will utilize focal cerebral I/R animal model to explore the function of BKCa channel in Et OH-PC protection in vivo levels by means of pharmacological intervention such as BKCa channel opene(rNS11021,NS)and blocke(rpaxilline,PX).The results will provide theoretical evidence for neuroprotective effect of moderate alcohol preconditioning against ischemic stroke,and the conclusion will also bring to a concept that extrinsic moderate ethanol preconditioning may activate intrinsic protective mechanism in the brain.METHODS The SD rat were randomly divided into the following six groups(n=10):sham,I/R,Et OH-PC+I/R,NS11021-PC+I/R,paxilline+Et OH-PC+I/R,Paxilline+NS11021-PC+I/R.Both Et OH-PC and NS11021-PC(0.1mg·kg-1;ip)were induced 24 h before I/R.The volume of 95%ethanol to be instilled(inμL)was calculated as follows:〔body weight(g)×0.6〕+0.3.This volume of ethanol was mixed in 0.3 m L of sterile distilled water just before administration to the animals by gavage.The Paxilline(2.5 mg·kg-1;ip)was administered 10min beforeEt OH-PC and NS11021-PC.The right middle cerebral artery occlusion(MCAO)was produced by inversion of a 4-0-nylon filament.The filament was withdrawn 2 h after onset of MCAO and then reperfused.Neurological deficits and infarct volume were measured 24 h after I/R.Another 36 rats were random展开更多
The aim of the current study was to investigate the pharmacological activity of glabridinon the isolated human saphenous vein (SV) and explore the underlying mechanisms. Samples of patients' SVs were removed durin...The aim of the current study was to investigate the pharmacological activity of glabridinon the isolated human saphenous vein (SV) and explore the underlying mechanisms. Samples of patients' SVs were removed during bypass surgery, and 4-mm lengths of the vessels were placedin Krebs solution at ±4℃ and hung in an isolated organ bath to assess their contraction/relaxationresponses. The contraction/relaxation responses were recorded to observe if the cyclic guanosinemonophosphate (cGMP)/protein kinase G (PKG) pathway mediates the relaxant effect of glabridinafter treatment with blockers like ODQ (a guanylate cyclase inhibitor), KT5823 (a PKG inhibitor),isobutylmethylxanthine [IBMX, a phosphodiesterase (PDE) inhibitor], and cantharidin [Cant,a myosin light-chain phosphatase (MLCP) inhibitor]. Moreover, nitric oxide (NO), cGMP, andPKG levels in SV tissues were determined by ELISA after incubation with glabridin, N(o)-nitro-L-arginine methyl ester (L-Name, a NO synthetase inhibitor), phenylephrine (PE), ODQ, IBMX,and KT5823. The results showed that glabridin relaxed the vascular smooth muscle of humanSV pretreated with PE in a dose-dependent manner, which was independent of the endothelium.The vasorelaxant effect of glabridin was only inhibited by iberiotoxin (IbTX), Cant, and KT5823.Glabridin increased cGMP and PKG levels in SV homogenates, whereas it did not alter the NOlevel. The enhancing efects of cGMP and PKG levels by glabridin were abolished by ODQ andKT5823. In conclusion, glabridin has a vasorelaxant effect, which is associated with the activationof BKc. channels and inhibition of PDE.展开更多
基金This study was supported in part by grants from the National Natural Science Foundation of China （No. 81070157 and No. 81370303）, Natural Science Foundation of Jiangsu Province （No. BK2011179）, Medical Key Personnel of Jiangsu Province （RC 2011034） and Top Qualified Personnel in Six Fields of Jiangsu Province （006） to Dr. Wang Ruxing.
文摘Objective This review focuses on the role of the large conductance calcium-activated potassium （BKCa） channels in diabetic vascular complications.Data sources Relevant articles published in English or Chinese from 1981 to present were selected from PubMed.The search terms were ＂BKCa channels＂ and ＂diabetes＂.Important references from selected articles were also retrieved.Study selection Articles regarding the role of BKCa channels in diabetic vascular complications and relevant mechanisms were selected.Results The BKCa channels are abundantly expressed in vascular smooth cells and play an important role in regulation of vascular tone.Multiple studies indicated that the expression and function of BKCa channels are altered by different mechanisms in diabetic vascular diseases such as coronary arterial disease,cerebral arterial disease,and diabetic retinopathy.Conclusion BKCa channels may play an important role in diabetic vascular complications and may be an effective therapeutic target for relieving and reducing the burden of diabetic vascular complications.
基金supported by the National Natural Science Foundation of China(81171097 and 81271312)the Beijing Key Laboratory of Translational Medicine for Cerebrovascular Disease,China(TMCD201502)
文摘Increasing evidence suggests that low to mod- erate ethanol ingestion protects against the deleterious effects of subsequent ischemia/reperfusion; however, the underlying mechanism has not been elucidated. In the present study, we showed that expression of the neuronal large-conductance, Ca2＋-activated K＋ channel （BKca） α- subunit was upregulated in cultured neurons exposed to oxygen-glucose deprivation/reoxygenation （OGD/R） compared with controls. Preconditioning with low-dose ethanol （10 mmol/L） increased cell survival rate in neurons subjected to OGD/R, attenuated the OGD/R-induced elevation of cytosolic Ca2＋ levels, and reduced the number of apoptotic neurons. Western blots revealed that ethanol preconditioning upregulated expression of the anti-apoptotic protein Bcl-2 and downregulated the pro-apoptotic protein Bax. The protective effect of ethanol precondi- tioning was antagonized by a BKα channel inhibitor, paxilline. Inside-out patches in primary neurons also demonstrated the direct activation of the BKCa channel by 10 mmol/L ethanol. The above results indicated that low- dose ethanol preconditioning exerts its neuroprotective effects by attenuating the elevation of cytosolic Ca2＋ and preventing neuronal apoptosis, and this is mediated by BKca channel activation.
基金supported by the National Natural Science Foundation of China(3067076381173661+2 种基金31300948)the Sichuan Technology and Education Committee(2011FZ0106and XYTD20100509ZZ010)
文摘Some drugs exert curative effects intracellu- larly, but their hydrophilic property prohibits the mem- brane-penetrating process and thus limits the curative efficacies, although this property guarantee their solubility in aqueous phase. An example is sodium tanshinone II-A sulfonate （DS-201）, a derivative of Chinese medical herb Danshen （Salvia miltiorrhiza） which is a BKc~ channel opener and a vasodilator. This study established and opti- mized a liposome delivery system which could pack and deliver DS-201 into HEK293 cells transfected with BKca channels, and DS-201 given this way significantly increased the open probability of BKca channel from baseline 0.013 ~ 0.004 to 0.036 -4- 0.011 at -t-40 mV membrane potential （P 〈 0.05） in single-channel attached study, and also increased the current density from baseline 23.2 ＋ 4.4 to 66.0 4- 15.2 pA/pF at ＋40 mV membrane potential （P 〈 0.05）, compared with the direct extracellular administration of this drug. Moreover, showing a ~ 60 % inhibition of the PE or PGF2a induced vascular constric- tion, the DS-201 liposomes did posses significantly enhanced vasorelaxant effect on rat mesenteric artery, compared with 20 % inhibition of the directly administration of this drug （P 〈 0.05）, suggesting that DS-201 delivered by liposomes significantly improved the drug＇s vasorelaxing effect. Taken together, the optimized DS-201 liposomes in our study successfully delivered DS-201 into cells and thus significantly activated BKca channels to reverse the contraction induced by PE and PGF2a, attesting the enhanced bioavailability.
文摘目的:研究茜草素对Wistar大鼠肾叶间动脉及其平滑肌细胞大电导钙激活钾通道(Large Conductance Calcium Activated Potassium Channels;BKCa)的影响。方法:压力型小动脉测量仪用于观察给予茜草素前后肾叶间动脉血管直径的变化;全细胞膜片钳技术用于研究茜草素对离体的Wistar大鼠肾叶间动脉平滑肌细胞BKCa介导的外向电流的调节作用。结果:(1)茜草素(10^(-7)~3×10^(-5)mol/L)舒张肾叶间动脉(P<0.01);(2)茜草素(10^(-7)~3×10^(-5)mol/L)增强Wistar大鼠肾叶间动脉平滑肌细胞外向电流(60 m V)呈浓度依赖性(P<0.05);(3)在0 m V^60 m V,茜草素(10-5mol/L)增强Wistar大鼠肾叶间动脉平滑肌细胞外向电流呈电压依赖性(P<0.05);(4)TEA(10-4mol/L)阻断茜草素(10-5mol/L)增强的肾叶间动脉平滑肌细胞外向电流(60 m V)(P<0.01);(5)10^(-7)mol/L的BKCa阻断剂伊比利亚毒素(ib TX)阻断茜草素(10^(-5)mol/L)对肾叶间动脉平滑肌细胞外向电流(60 m V)的增强作用(P<0.01)。结论:茜草素通过激活更多BKCa开放促进钾离子外流,引起Wistar大鼠肾叶间动脉平滑肌细胞超极化,舒张肾叶间动脉血管。
文摘There is accumulating evidence that the subfamily of large-conductance potassium (“big”, “BK”) channels are involved in diverse, and perhaps coordinated, protective or counteractive responses to local or generalized ischemia and hypoxia. Although widely distributed, the physiological differences among BK channels which results from posttranslational modification (alternative splicing) and co-assembly with auxiliary modulatory subunits (<em>β</em><sub>1-4</sub> and <em>γ</em><sub>1-4</sub>), bestows localized differences in subunit composition, distribution, 2<sup>nd</sup>-messenger coupling, and pharmacologic properties. Due to the ubiquitous nature of BK channels and the multiplicity of subtypes, they have many potential therapeutic applications in the maintenance of oxygen homeostasis, cerebro- and cardio-protection, and stimulation of respiration in response to drug-induced respiratory depression. BK channels may also offer other potentially broad and underrecognized promising targets for novel pharmaceutical development.
基金The National Natural Science Foundation of Chinagrant number:10972024,11120101001,10925208,and 10802006+3 种基金Doctoral Fund of Ministry of Education of Chinagrant number:0800061001National Basic Research Program of Chinagrant number:2011CB710901
文摘Large conductance Ca^(2+)-activated K^+ (BK_(Ca)) channel exhibits a phenotype-dependent expression on vascular smooth muscle cells(VSMCs), which prefers to contractile phenotype. Meanwhile, shear stress definitely influences VSMCs proliferation and contraction. Thereby, a hypothesis was raised, would shear stress change the BK_(Ca)expression and correlate with VSMC phenotype? In order to investigate it, VSMCs were exposed to shear stress in a parallel-plate flow chamber with 12 dynes/cm^2 for 12 h. Subsequently, the effect of shear stress on VSMC proliferation, BK_(Ca)channel expression and contractile phenotype marker, α-smooth muscle cell actin(α-SMA) and smooth muscle myosin heavy chain(SMMHC), was determined by immunofluorescence microscopy, flow cytometery as well as reverse transcriptionpolymerase chain reaction(RT-PCR), respectively. Data show that shear stress enhanced the expression of BK_(Ca)channel while inhibiting VSMC proliferation.Paralleled to those phenomena, the expression of both α-SMA and SM-MHC were decreased significantly. These results demonstrated that upregulation of BK_(Ca)channel was irrelevant to the maintenance VSMC of contractile phenotype under shear stress.This finding provides a new insight into understanding the correlation of BK_(Ca)channel and VSMC phenotype.
基金The project supported by NSFC(81171079,81271312)
文摘OBJCETIVE Epidemiologic studies have demonstrated that consumption of moderate amounts of red wine is associated with significant reductions in incidences of cardiovascular and cerebrovascular diseases,which may be related to alcohol in red wine.Our previous study demonstrated that ethanol ingestion 24 h prior to induction of cerebral ischemic/reperfusion(I/R)reduced delayed neuronal death(DND).Our most recent results supported a role for big Ca2+-sensitive K+channel(BKCa channel)activation in the neuroprotective effects of ethanol preconditioning(Et OH-PC)in global cerebral I/R.Therefore,we hypothesis that moderate Et OH-PC activates BKCa channel to protect brain damage induced by focal cerebral I/R.This project will utilize focal cerebral I/R animal model to explore the function of BKCa channel in Et OH-PC protection in vivo levels by means of pharmacological intervention such as BKCa channel opene(rNS11021,NS)and blocke(rpaxilline,PX).The results will provide theoretical evidence for neuroprotective effect of moderate alcohol preconditioning against ischemic stroke,and the conclusion will also bring to a concept that extrinsic moderate ethanol preconditioning may activate intrinsic protective mechanism in the brain.METHODS The SD rat were randomly divided into the following six groups(n=10):sham,I/R,Et OH-PC+I/R,NS11021-PC+I/R,paxilline+Et OH-PC+I/R,Paxilline+NS11021-PC+I/R.Both Et OH-PC and NS11021-PC(0.1mg·kg-1;ip)were induced 24 h before I/R.The volume of 95%ethanol to be instilled(inμL)was calculated as follows:〔body weight(g)×0.6〕+0.3.This volume of ethanol was mixed in 0.3 m L of sterile distilled water just before administration to the animals by gavage.The Paxilline(2.5 mg·kg-1;ip)was administered 10min beforeEt OH-PC and NS11021-PC.The right middle cerebral artery occlusion(MCAO)was produced by inversion of a 4-0-nylon filament.The filament was withdrawn 2 h after onset of MCAO and then reperfused.Neurological deficits and infarct volume were measured 24 h after I/R.Another 36 rats were random
文摘The aim of the current study was to investigate the pharmacological activity of glabridinon the isolated human saphenous vein (SV) and explore the underlying mechanisms. Samples of patients' SVs were removed during bypass surgery, and 4-mm lengths of the vessels were placedin Krebs solution at ±4℃ and hung in an isolated organ bath to assess their contraction/relaxationresponses. The contraction/relaxation responses were recorded to observe if the cyclic guanosinemonophosphate (cGMP)/protein kinase G (PKG) pathway mediates the relaxant effect of glabridinafter treatment with blockers like ODQ (a guanylate cyclase inhibitor), KT5823 (a PKG inhibitor),isobutylmethylxanthine [IBMX, a phosphodiesterase (PDE) inhibitor], and cantharidin [Cant,a myosin light-chain phosphatase (MLCP) inhibitor]. Moreover, nitric oxide (NO), cGMP, andPKG levels in SV tissues were determined by ELISA after incubation with glabridin, N(o)-nitro-L-arginine methyl ester (L-Name, a NO synthetase inhibitor), phenylephrine (PE), ODQ, IBMX,and KT5823. The results showed that glabridin relaxed the vascular smooth muscle of humanSV pretreated with PE in a dose-dependent manner, which was independent of the endothelium.The vasorelaxant effect of glabridin was only inhibited by iberiotoxin (IbTX), Cant, and KT5823.Glabridin increased cGMP and PKG levels in SV homogenates, whereas it did not alter the NOlevel. The enhancing efects of cGMP and PKG levels by glabridin were abolished by ODQ andKT5823. In conclusion, glabridin has a vasorelaxant effect, which is associated with the activationof BKc. channels and inhibition of PDE.
