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 opene...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.展开更多
Background Previous studies suggested that mechanical intervention during early reperfusion, or ischemia postconditioning （Ipo）, could protect kidneys against renal ischemia reperfusion injury （RIRI）. However, the...Background Previous studies suggested that mechanical intervention during early reperfusion, or ischemia postconditioning （Ipo）, could protect kidneys against renal ischemia reperfusion injury （RIRI）. However, the mechanisms responsible for this protection remain unclear. This study therefore investigated the protection afforded by Ipo in rat kidneys in vivo, and the roles of mitochondrial KATP channels （mitOKATP） and mitochondrial permeability transition pores （MPTPs）, by inhibiting mitOKATP with 5-hydroxydecanoate （5-HD）, and by directly detecting open MPTPs using calcein-AM and CoCl2.Methods Thirty-five male Sprague-Dawley rats were randomly assigned to sham-operation （S）, ischemia-reperfusion （I/R）,Ipo, ischemia reperfusion with 5-HD （I/R＋5-HD）, or Ipo with 5-HD （Ipo ＋5-HD） groups. Rats in each group were sacrificed after 6 hours of reperfusion by heart exsanguination or cervical dislocation under anesthesia. RIRI was assessed by determination of creatinine and blood urea nitrogen （BUN）, and by examination of histologic sections. The roles of mitoKATP and MPTP were investigated by analyzing fluorescence intensities of mitochondria, mitochondrial membrane potential,intracellular reactive oxygen species （ROS） and intracellular calcium, using appropriate fluorescent markers. The relationship between apoptosis and RIRI was assessed by determining the apoptotic index （Al） of kidney tubular epithelial cells.Results The RIRI model was shown to be successful. Significantly higher levels of creatinine and BUN, and abnormal pathology of histologic sections, were observed in group I/R, compared with group S. 5-HD eliminated the renoprotective effects of Ipo. Mitochondrial and mitochondrial membrane potential fluorescence intensities increased, and intracellular calcium, ROS fluorescence intensities and AI decreased in group Ipo, compared with group I/R. However, mitochondrial and mitochondrial membrane potential fluorescence intensities decreased, and intracellular calcium and ROS fluorescence intensities and AI increased in group Ipo＋5-HD, compared with group Ipo.Conclusions mitoKATP and MPTPs participated in Ipo-induced renoprotective mechanisms in rat kidneys subjected to RIRI, possibly through decreased renal tubular epithelial cell apoptosis.展开更多
文摘目的 通过研究高效氯氰菊酯与德国小蠊Na K ATPase活性水平的量效与时效关系 ,进一步完善高效氯氰菊酯作用机制的研究 ,为德国小蠊的防制工作提供理论基础和方法参考。方法 参照国标GB 13917 1～ 13917 8- 92《农药登记卫生杀虫剂室内药效试验方法》喷施一定剂量不同浓度的高效氯氰菊酯 ,用ATP酶测定试剂盒测定德国小蠊Na K ATPase活性。结果 4 8h内高效氯氰菊酯对德国小蠊Na K ATPase活性的抑制作用呈浓度梯度效应 ,高效氯氰菊酯的浓度与德国小蠊 72h的死亡率和 14 4h内对Na K ATPase活性的抑制时效呈正相关。结论 Na K ATPase是高效氯氰菊酯的作用靶标之一 ,Na K ATPase敏感度降低而产生的靶标抗性可能是德国小蠊对高效氯氰菊酯产生抗药性的重要原因之一。
文摘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.
基金This study was supported by a grant from Natural Science Foundation of Hebei Province （No. C2011307006）.
文摘Background Previous studies suggested that mechanical intervention during early reperfusion, or ischemia postconditioning （Ipo）, could protect kidneys against renal ischemia reperfusion injury （RIRI）. However, the mechanisms responsible for this protection remain unclear. This study therefore investigated the protection afforded by Ipo in rat kidneys in vivo, and the roles of mitochondrial KATP channels （mitOKATP） and mitochondrial permeability transition pores （MPTPs）, by inhibiting mitOKATP with 5-hydroxydecanoate （5-HD）, and by directly detecting open MPTPs using calcein-AM and CoCl2.Methods Thirty-five male Sprague-Dawley rats were randomly assigned to sham-operation （S）, ischemia-reperfusion （I/R）,Ipo, ischemia reperfusion with 5-HD （I/R＋5-HD）, or Ipo with 5-HD （Ipo ＋5-HD） groups. Rats in each group were sacrificed after 6 hours of reperfusion by heart exsanguination or cervical dislocation under anesthesia. RIRI was assessed by determination of creatinine and blood urea nitrogen （BUN）, and by examination of histologic sections. The roles of mitoKATP and MPTP were investigated by analyzing fluorescence intensities of mitochondria, mitochondrial membrane potential,intracellular reactive oxygen species （ROS） and intracellular calcium, using appropriate fluorescent markers. The relationship between apoptosis and RIRI was assessed by determining the apoptotic index （Al） of kidney tubular epithelial cells.Results The RIRI model was shown to be successful. Significantly higher levels of creatinine and BUN, and abnormal pathology of histologic sections, were observed in group I/R, compared with group S. 5-HD eliminated the renoprotective effects of Ipo. Mitochondrial and mitochondrial membrane potential fluorescence intensities increased, and intracellular calcium, ROS fluorescence intensities and AI decreased in group Ipo, compared with group I/R. However, mitochondrial and mitochondrial membrane potential fluorescence intensities decreased, and intracellular calcium and ROS fluorescence intensities and AI increased in group Ipo＋5-HD, compared with group Ipo.Conclusions mitoKATP and MPTPs participated in Ipo-induced renoprotective mechanisms in rat kidneys subjected to RIRI, possibly through decreased renal tubular epithelial cell apoptosis.
