The ATP-sensitive potassium（KATP）channels which extensively distribute in diverse tissues（e.g.vascular smooth muscle,cardiac cells,and pancreas）are well-established for characteristics like vasodilatation,myocardi...The ATP-sensitive potassium（KATP）channels which extensively distribute in diverse tissues（e.g.vascular smooth muscle,cardiac cells,and pancreas）are well-established for characteristics like vasodilatation,myocardial protection against ischemia,and insulin secretion.The aim of this review is to get insight into the novel roles of KATPchannels in Parkinson＇s disease（PD）,with consideration of the specificities KATPchannels in the central nervous system（CNS）, such as the control of neuronal excitability,action potential,mitochondrial function and neurotransmitter release.展开更多
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...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.展开更多
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...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.展开更多
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 cer...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.展开更多
Subject Code:C05 With the support by the National Natural Science Foundation of China,the collaborative research team led by Prof.Chen Lei(陈雷)at the State Key Laboratory of Membrane Biology,Institute of Molecular Me...Subject Code:C05 With the support by the National Natural Science Foundation of China,the collaborative research team led by Prof.Chen Lei(陈雷)at the State Key Laboratory of Membrane Biology,Institute of Molecular Medicine,Peking-Tsinghua Center for Life Sciences,Beijing Key Laboratory of Cardiometabolic展开更多
Objective: This study aims to investigate the effects of urocortin (Ucn) on the viability of endothelial cells (ECV304) and rat vascular muscle cells (VSMC). Methods: Rat aortic VSMC were isolated from the rats' t...Objective: This study aims to investigate the effects of urocortin (Ucn) on the viability of endothelial cells (ECV304) and rat vascular muscle cells (VSMC). Methods: Rat aortic VSMC were isolated from the rats' thoracic aorta. We studied the effect of Ucn on the viability of ECV304 cells and VSMC by using a tetrazolium (MTT) assay.Results: Ucn (10 -7 mol/L) inhibited the viability of ECV304 cells and VSMC. Inhibition rates are 13% and 15%, respectively(P<0.05, compared with Control). This inhibition was not dependent on the affecting time and was not affected by the addition of ATP-sensitive potassium channel (KATP channel) blocker, glybenclamide (Gly, 10 mol/L). Conclusion: Ucn inhibits the viability of ECV304 and VSMC. Our results suggest that Ucn may be a new vasoactive agent and may have a beneficial effect in the process of vascular remodeling (VR).展开更多
Diazoxide, an activator of mitochondrial ATP-sensitive potassium channels, can protect neurons and astrocytes against oxidative stress and apoptosis. In this study, we established a cellular mode of epilepsy by cultur...Diazoxide, an activator of mitochondrial ATP-sensitive potassium channels, can protect neurons and astrocytes against oxidative stress and apoptosis. In this study, we established a cellular mode of epilepsy by culturing hippocampal neurons in magnesium-free medium, and used this to investigate effects of diazoxide preconditioning on the expression of inwardly rectifying potassium channel （Kir） subunits of the ATP-sensitive potassium. We found that neuronal viability was significantly reduced in the epileptic cells, whereas it was enhanced by diazoxide preconditioning. Double immunofluorescence and western blot showed a significant increase in the expression of Kir6.1 and Kir6.2 in epileptic cells, especially at 72 hours after seizures. Diazoxide pretreatment completely reversed this effect at 24 hours after seizures. In addition, Kir6.1 expression was significantly upregulated compared with Kir6.2 in hippocampal neurons after seizures. These findings indicate that diazoxide pretreatment may counteract epileptiform discharge-induced cytotoxicity by suppressing the expression of Kir subunits.展开更多
Background The myocardial ATP sensitive potassium channel （KATP channel） has been known for more than two decades, the properties of this channel have been intensively investigated, especially the myocardial protect...Background The myocardial ATP sensitive potassium channel （KATP channel） has been known for more than two decades, the properties of this channel have been intensively investigated, especially the myocardial protection effect by opening this channel. Numerous studies, including hypothermic, using KATP agonists to achieve a hyperpolarizing cardioplegic arrest, have shown a better myocardial protection than potassium arrest. However, there is no evidence showing that KATP channel could be opened by its agonists under profound hypothermia. We investigated the effect of temperature on activation of myocardial KATP channel by nicorandil.Methods Isolated ventricular myocytes were obtained by collagenase digestion of the hearts of guinea pigs and stored in KB solution at 4℃. With a steady ground current, the myocytes were perfused with 1 mmol/L nicorandil until a steady IKATP occurred. Then the cells were perfused with 1 mmol/L nicorandil plus 1 μmol/L glybenclamide. Currents signals were recorded on whole cells using patch clamp technique at several temperatures. The temperature of the bath solution around myocytes was monitored and was controlled at 4℃, 10℃, 20℃, 25℃ and 35℃ respectively. About 10 cells were tested at each temperature, the cells were considered useful only when the outward current could be induced by nicorandil and blocked by glybenclamide. All data were analyzed using Graphpad PRISM 3.0 （Graphpad, San Diego, CA, USA）. Nonlinear curve fitting was done in Clampfit （Axon） or Sigmaplot （SPSS）.Results At 4℃, 10℃, 20℃, 25℃ and 35℃, the time needed to open the myocardial KATP channel was （81.0±0） minutes, （50.54±11.7） minutes, （28.84±2.3） minutes, （9.4± 10.2） minutes and （2.3± 1.0） minutes respectively （P=0.003）. The linear relationship between temperature and time needed to open the channel was y （min） = （4348.790±124.277x）/60, where y （min） is time needed to open KATP channel, x is temperature, correlation coefficient r =-0.942 （P=0.00）, regression coefficient b =-124.277 （P=0.00）. The current densities among different temperatures were statistically different （P=0.022）, the current density was greater after the activation of KATP channel at higher temperatures. The lower the temperature, the fewer cells in which KATP channels could be opened. At 4℃, only one cell in which the KATP channel could be opened, took a quite long time （81 minutes）and the Ⅰ-Ⅴ curve was quite untypical.Conclusions KATP channel activated by nicorandil is temperature dependent and the temperature linearly related to time needed to open KATP channel; the lower the temperature, the longer the time needed to open channel and the smaller the current density. At profound hypothermia, it is difficult to activate KATP channels.展开更多
The myocardial protection afforded by ischernic preconditioning （IPC） can alleviate ischemi- a-repel-fusion injury in normal rat heart. However, this myocardial protection is seldom studied in the type 2 diabetic ra...The myocardial protection afforded by ischernic preconditioning （IPC） can alleviate ischemi- a-repel-fusion injury in normal rat heart. However, this myocardial protection is seldom studied in the type 2 diabetic rat with myocardial ischemia disease. In this study, we aimed to evaluate the effects of ATP-sensitive potassium channels （KATP channels） on IPC in the isolated type 2 diabetic rat heart and the role of the sul- fonylurea gliclazide. Methods Streptozotocin（STZ）-induced type 2 diabetic male Wistar rats with or without gliclazide （64 mg/kg body weight, orally） and age-matched non-diabetic control rats were used for all studies. The isolated hearts were perfused with Langendorff＇s system under the constant flow, pressure and tempera- ture conditions with Kreb＇s-Henseleit solution （K-H）. After 5 minutes of balance peffusion, these rats were randomly divided into six groups： non-diabetic control rats without IPC （CIR） ; non-diabetic control rats with IPC （CIP）; diabetic rats without 1PC （DIR）; diabetic rats with IPC （DIP）; gliclazide-treated diabetic rats without IPC （GIR）; and gliclazide-treated diabetic rats with IPC （GIP）. Groups CIR, DIR, and GIR were subjected to 30-rain global ischemia and 60-rain reperfusion for induction of ischemia/reperfusion injury. Groups CIP, DIP, and GIP were given three cycles of 5-min ischemia and 5-rain reperfusion as IPC, and then ischemia/reperfusion injury program was implemented. Extent of ischemia/reperfusion injury was measured in terms of the release of lactate dehydrogenase （LDH）, creatine kinase （CK）, and creatin kinase-MB （CK- MB） in coronary effluent. After perfusion, Kir6.2 and SUR2A mRNA expressions in the myocardial tissue were characterized by fluorescent quantitative real-time PCR method, and Kir6.2 and SUR2A protein expres- sions were assessed by immunohistochemistry. Result In non-diabetic control rats, the release of LDH, CK, and CK-MB in coronary effluent markedly decreased with IPC compared with No-IPC （P 〈 0.05）, but not in diabetic rats. However, in gliclazide-treated diabetic rats, IPC-induced decrease in the release of LDH, CK, and CK-MB was restored compared with No-IPC （P 〈 0.05）. The expressions of Kir6.2 both at mRNA and protein levels in CIP were significantly higher than those in CIR. There was no significant difference in theexpression of Kir6.2 and SUR2A both at mRNA and protein levels between DIP and DIR. However, the expression of Kir6.2 both at mRNA and protein levels was significantly higher in GIP than in GIR. No significant difference was detected in the mRNA expression level of SUR2A between the six groups. The expression of SUR2A at protein level was significantly higher in CIP than in CIR and in GIP than in GIR. Conclusions The cardioprotective effect of IPC is abolished in the isolated type 2 diabetic rats compared with non-diabetic control rats. However, to some extent, gliclazide can improve the myocardial protection of IPC against ischemia/reperfusion injury, thus suggesting that it is mediated mainly by KATP channels at mRNA or protein level, which provides a basis for further investigating the effects of KATP channels on IPC.展开更多
基金the National Natural Science Foundation of China（No.30700251）；the National Basic Research Development Program of China（No.2006CB500706）；the Young Excellent Scholar（2007-2008）Program of Shanghai Jiaotong University School of Medicine.
文摘The ATP-sensitive potassium（KATP）channels which extensively distribute in diverse tissues（e.g.vascular smooth muscle,cardiac cells,and pancreas）are well-established for characteristics like vasodilatation,myocardial protection against ischemia,and insulin secretion.The aim of this review is to get insight into the novel roles of KATPchannels in Parkinson＇s disease（PD）,with consideration of the specificities KATPchannels in the central nervous system（CNS）, such as the control of neuronal excitability,action potential,mitochondrial function and neurotransmitter release.
文摘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.
基金the Natural Science Foundation of Liaoning Province,No.20052097,2008225010
文摘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.
文摘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.
文摘Subject Code:C05 With the support by the National Natural Science Foundation of China,the collaborative research team led by Prof.Chen Lei(陈雷)at the State Key Laboratory of Membrane Biology,Institute of Molecular Medicine,Peking-Tsinghua Center for Life Sciences,Beijing Key Laboratory of Cardiometabolic
文摘Objective: This study aims to investigate the effects of urocortin (Ucn) on the viability of endothelial cells (ECV304) and rat vascular muscle cells (VSMC). Methods: Rat aortic VSMC were isolated from the rats' thoracic aorta. We studied the effect of Ucn on the viability of ECV304 cells and VSMC by using a tetrazolium (MTT) assay.Results: Ucn (10 -7 mol/L) inhibited the viability of ECV304 cells and VSMC. Inhibition rates are 13% and 15%, respectively(P<0.05, compared with Control). This inhibition was not dependent on the affecting time and was not affected by the addition of ATP-sensitive potassium channel (KATP channel) blocker, glybenclamide (Gly, 10 mol/L). Conclusion: Ucn inhibits the viability of ECV304 and VSMC. Our results suggest that Ucn may be a new vasoactive agent and may have a beneficial effect in the process of vascular remodeling (VR).
基金supported by the Technology Development Plan of Linyi City, No. 201113002
文摘Diazoxide, an activator of mitochondrial ATP-sensitive potassium channels, can protect neurons and astrocytes against oxidative stress and apoptosis. In this study, we established a cellular mode of epilepsy by culturing hippocampal neurons in magnesium-free medium, and used this to investigate effects of diazoxide preconditioning on the expression of inwardly rectifying potassium channel （Kir） subunits of the ATP-sensitive potassium. We found that neuronal viability was significantly reduced in the epileptic cells, whereas it was enhanced by diazoxide preconditioning. Double immunofluorescence and western blot showed a significant increase in the expression of Kir6.1 and Kir6.2 in epileptic cells, especially at 72 hours after seizures. Diazoxide pretreatment completely reversed this effect at 24 hours after seizures. In addition, Kir6.1 expression was significantly upregulated compared with Kir6.2 in hippocampal neurons after seizures. These findings indicate that diazoxide pretreatment may counteract epileptiform discharge-induced cytotoxicity by suppressing the expression of Kir subunits.
基金This work was supported by a grant from the Natural Science Foundation of China (No. 30371374).
文摘Background The myocardial ATP sensitive potassium channel （KATP channel） has been known for more than two decades, the properties of this channel have been intensively investigated, especially the myocardial protection effect by opening this channel. Numerous studies, including hypothermic, using KATP agonists to achieve a hyperpolarizing cardioplegic arrest, have shown a better myocardial protection than potassium arrest. However, there is no evidence showing that KATP channel could be opened by its agonists under profound hypothermia. We investigated the effect of temperature on activation of myocardial KATP channel by nicorandil.Methods Isolated ventricular myocytes were obtained by collagenase digestion of the hearts of guinea pigs and stored in KB solution at 4℃. With a steady ground current, the myocytes were perfused with 1 mmol/L nicorandil until a steady IKATP occurred. Then the cells were perfused with 1 mmol/L nicorandil plus 1 μmol/L glybenclamide. Currents signals were recorded on whole cells using patch clamp technique at several temperatures. The temperature of the bath solution around myocytes was monitored and was controlled at 4℃, 10℃, 20℃, 25℃ and 35℃ respectively. About 10 cells were tested at each temperature, the cells were considered useful only when the outward current could be induced by nicorandil and blocked by glybenclamide. All data were analyzed using Graphpad PRISM 3.0 （Graphpad, San Diego, CA, USA）. Nonlinear curve fitting was done in Clampfit （Axon） or Sigmaplot （SPSS）.Results At 4℃, 10℃, 20℃, 25℃ and 35℃, the time needed to open the myocardial KATP channel was （81.0±0） minutes, （50.54±11.7） minutes, （28.84±2.3） minutes, （9.4± 10.2） minutes and （2.3± 1.0） minutes respectively （P=0.003）. The linear relationship between temperature and time needed to open the channel was y （min） = （4348.790±124.277x）/60, where y （min） is time needed to open KATP channel, x is temperature, correlation coefficient r =-0.942 （P=0.00）, regression coefficient b =-124.277 （P=0.00）. The current densities among different temperatures were statistically different （P=0.022）, the current density was greater after the activation of KATP channel at higher temperatures. The lower the temperature, the fewer cells in which KATP channels could be opened. At 4℃, only one cell in which the KATP channel could be opened, took a quite long time （81 minutes）and the Ⅰ-Ⅴ curve was quite untypical.Conclusions KATP channel activated by nicorandil is temperature dependent and the temperature linearly related to time needed to open KATP channel; the lower the temperature, the longer the time needed to open channel and the smaller the current density. At profound hypothermia, it is difficult to activate KATP channels.
基金supported by the Qingdao Municipal Science and Technology Commission (No. 11-2-3-2-(12)-nsh)
文摘The myocardial protection afforded by ischernic preconditioning （IPC） can alleviate ischemi- a-repel-fusion injury in normal rat heart. However, this myocardial protection is seldom studied in the type 2 diabetic rat with myocardial ischemia disease. In this study, we aimed to evaluate the effects of ATP-sensitive potassium channels （KATP channels） on IPC in the isolated type 2 diabetic rat heart and the role of the sul- fonylurea gliclazide. Methods Streptozotocin（STZ）-induced type 2 diabetic male Wistar rats with or without gliclazide （64 mg/kg body weight, orally） and age-matched non-diabetic control rats were used for all studies. The isolated hearts were perfused with Langendorff＇s system under the constant flow, pressure and tempera- ture conditions with Kreb＇s-Henseleit solution （K-H）. After 5 minutes of balance peffusion, these rats were randomly divided into six groups： non-diabetic control rats without IPC （CIR） ; non-diabetic control rats with IPC （CIP）; diabetic rats without 1PC （DIR）; diabetic rats with IPC （DIP）; gliclazide-treated diabetic rats without IPC （GIR）; and gliclazide-treated diabetic rats with IPC （GIP）. Groups CIR, DIR, and GIR were subjected to 30-rain global ischemia and 60-rain reperfusion for induction of ischemia/reperfusion injury. Groups CIP, DIP, and GIP were given three cycles of 5-min ischemia and 5-rain reperfusion as IPC, and then ischemia/reperfusion injury program was implemented. Extent of ischemia/reperfusion injury was measured in terms of the release of lactate dehydrogenase （LDH）, creatine kinase （CK）, and creatin kinase-MB （CK- MB） in coronary effluent. After perfusion, Kir6.2 and SUR2A mRNA expressions in the myocardial tissue were characterized by fluorescent quantitative real-time PCR method, and Kir6.2 and SUR2A protein expres- sions were assessed by immunohistochemistry. Result In non-diabetic control rats, the release of LDH, CK, and CK-MB in coronary effluent markedly decreased with IPC compared with No-IPC （P 〈 0.05）, but not in diabetic rats. However, in gliclazide-treated diabetic rats, IPC-induced decrease in the release of LDH, CK, and CK-MB was restored compared with No-IPC （P 〈 0.05）. The expressions of Kir6.2 both at mRNA and protein levels in CIP were significantly higher than those in CIR. There was no significant difference in theexpression of Kir6.2 and SUR2A both at mRNA and protein levels between DIP and DIR. However, the expression of Kir6.2 both at mRNA and protein levels was significantly higher in GIP than in GIR. No significant difference was detected in the mRNA expression level of SUR2A between the six groups. The expression of SUR2A at protein level was significantly higher in CIP than in CIR and in GIP than in GIR. Conclusions The cardioprotective effect of IPC is abolished in the isolated type 2 diabetic rats compared with non-diabetic control rats. However, to some extent, gliclazide can improve the myocardial protection of IPC against ischemia/reperfusion injury, thus suggesting that it is mediated mainly by KATP channels at mRNA or protein level, which provides a basis for further investigating the effects of KATP channels on IPC.
