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Sulfonylureas are widely used oral anti-diabetic drugs. However, its long-term usage effects on patients' lifespan remain controversial, with no reports of influence on animal longevity. Hence, the anti-aging effects of chlorpropamide along with glimepiride, glibenclamide, and tolbutamide were studied with special emphasis on the interaction of chlorpropamide with mitochondrial ATP-sensitive K+ (mitoK-ATP) channels and mitochondrial complex II. Chlorpropamide delayed aging in Caenorhabditis elegans, human lung fibroblast MRC-5 cells and reduced doxorubicin-induced senescence in both MRC-5 cells and mice. In addition, the mitochondrial membrane potential and ATP levels were significantly increased in chlorpropamide-treated worms, which is consistent with the function of its reported targets, mitoK-ATP channels. Increased levels of mitochondrial reactive oxygen species (mtROS) were observed in chlorpropamide-treated worms. Moreover, the lifespan extension by chlorpropamide required complex II and increased mtROS levels, indicating that chlorpropamide acts on complex II directly or indirectly via mitoK-ATP to increase the production of mtROS as a pro-longevity signal. This study provides mechanistic insight into the anti-aging effects of sulfonylureas in C. elegans.
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@#Objective To explore the effect and mechanism of exercise preconditioning on neurological deficits in rats after cerebral ischemia-reperfusion. Methods Thirty-six healthy Sprague-Dawley rats were randomly divided into sham group (n=12), model group (n=12) and exercise preconditioning group (n=12). The latter two groups were occluded middle cerebral artery for 120 minutes and reperfused with modified suture method. The rats were evaluated with Longa's score two, twelve and 24 hours after reperfusion. The expression of mitochondrial ATP-sensitive potassium (mitoKATP) channel proteins inwardly rectifying potassium channel (Kir6.2) and sulphonylurea receptor 1 (SUR1) were detected with Western blotting and the cerebral cell apoptosis was detected with TUENL assay 24 hours after reperfusion. Results Compared with the model group, the Longa's score decreased in the exercise preconditioning group 24 hours after reperfusion (P<0.05), while the expression of Kir6.2 and SUR1 decreased (P<0.05), and TUNEL-positive cells decreased (P<0.05).Conclusion Exercise preconditioning may improve neurological function after cerebral ischemia-reperfusion, which may associate with inhibiting the expression of mitoKATP channel proteins and cell apoptosis.
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Two patients with neonatal diabetes tested as V59A and V59M mutations were chosen for the study. Clinical data were analyzed retrospectively. The results showed that the patient with V59A mutation was characteristic of spasm and hyperglycemia at the age of three month, and treated with insulin for a long time as unresponsive to the glibenclamide at the beginning. Myasthenia and delay of development were observed during the follow-up. At the age of two years, glibenclamide was tried for the second time with a high dose and fairly-controlled glucose level. The patient with V59M mutation was diagnosed with diarrhea, hyperglycemia, and ketosis at the age of two month, and was responsive to glibenclamide at a relatively low dose with well-controlled glucose level. These results suggest that KCNJ11 V59M mutation would show some milder clinical manifestations and better glibenclamide efficacy as compared with V59A mutation.
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Aim To investigate the role of ATP-sensi-tive potassium channels-Akt pathway in exogenous hy-drogen sulfide( H2 S) inhibiting the high glucose( HG)-induced injury in H9c2 cardiac cells. Methods The expression level of Akt protein was tested by Western blot assay. The cell viability was measured by cell counter kit-8(CCK-8 assay). The number of apoptotic cells was tested by Hoechst 33258 nuclear staining fol-lowed by photofluorography. The intracellular levels of reactive oxygen species ( ROS ) were detected by DCFH-DA staining followed by photofluorography. Mi-tochondrial membrane potential ( MMP ) was examined by JC-1 staining followed by photofluorography. Results H9c2 cells were treated with 35 mmol·L-1 glucose (high glucose, HG) for 0 ~24 h respectively. After treating for 3 h, the expression level of phosphorated ( p )-Akt protein began to be obviously reduced, the maximum reduced expression level was observed after the cells were exposed to HG for 24 h. Pretreatment of the cells with 50 μmol · L-1 pinacidil ( Pin, a KATP channel opener) or 400 μmol·L-1 NaHS( a donor of H2 S) prior to exposure to HG considerably blocked the down regulation of p-Akt expression level induced by HG. However, pretreatment with 1 mmol · L-1 KATP channel blocker glibenclamide( Gli) obviously attenua-ted the inhibitory effect of NaHS on HG-induced down-regulation of p-Akt expression level. On the other hand, the protective effects of NaHS against the HG-induced cardiomyocyte injury were markedly blocked by 30 μmol·L-1 Ly294002(an inhibitor of Akt), as indicated by the decrease in cell viability and MMP dissipation as well as the increases in the number of apoptotic cells and ROS generation. Conclution KATP channels-Akt pathway mediates the protective effect of H2 S against the HG-induced cardiac injury.
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Aim To observe the influences of dexmen-detomidine on the spontaneous contraction of duodenal smooth muscle of rabbits in vitro and explore the mech-anisms.Methods The rabbits ( male or female ) were stunned and the duodenums were isolated .The sam-ples of duodenal segments were connected with tension transducer , which were then put into oxygen saturation Krebs-Henseleit ( K-H) solution .The influences of dex-mendetomidine on amplitude ( AM ) and frequency ( FR ) of duodenal smooth muscle were recorded by BL-420 F biological signal processing system .The cu-mulative dosing method was used to observe the differ-ent concentrations of dexmedetomidine on duodenal smooth muscle spontaneous contraction .Glibenclamide ( Gli) was added to K-H solution before dexmendeto-midine.In the calcium-free K-H solution, calcium chloride and rynodine were added before dexmendeto-midine.The mechanisms of dexmendetomidine were studied .Results ① Dexmendetomidine reduced the amplitude of spontaneous contraction of duodenal smooth muscle in rabbits in a dose-dependent manner ( P0.05 ) .② Gli ( P <0.05 ) partly abolished the inhibitory effects of dexmendetomi-dine on duodenal smooth muscle .③ Dexmendetomi-dine inhibited the contraction of duodenum smooth muscle induced by calcium chloride ( P <0.05 ) and rynodine ( P<0.05 ) application into calcium-free K-H solution.Conclusion Dexmendetomidine inhibits the spontaneous contraction of duodenal smooth muscle of rabbits in vitro.The mechanisms may be related to ac-tivating ATP sensitive potassium channels , inhibition of the extracellular calcium influx via cell membrane and intracellular calcium release via sarcoplasmic reticulum in duodenal smooth muscle .
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Nicorandil is a commonly used antianginal agent, which has both nitrate‑like and ATP‑sensitive potassium (KATP) channel activator properties. Activation of potassium channels by nicorandil causes expulsion of potassium ions into the extracellular space leading to membrane hyperpolarization, closure of voltage‑gated calcium channels and finally vasodilatation. However, on the other hand, being an activator of KATP channel, it can expel K+ ions out of the cells and can cause hyperkalemia. Here, we report a case of nicorandil induced hyperkalemia unresponsive to medical treatment in a patient with diabetic nephropathy.
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Aged , Channelopathies/chemically induced , Humans , Hyperkalemia , KATP Channels , Male , Nicorandil/adverse effects , Potassium Channels , Syndrome/chemically inducedABSTRACT
[ ABSTRACT] AIM:To investigate the potential role of exogenous hydrogen sulfide ( H2 S) and ATP-sensitive po-tassium ( KATP ) channels in chronic stress-induced colonic hypermotility.METHODS:Male Wistar rats were divided into water avoidance stress ( WAS) group and sham WAS ( SWAS) group.Organ bath recordings were used to test the contrac-tile activity of colonic strips.The effects of H2 S donor NaHS and pretreatment with glibenclamide on the contractions of co-lonic smooth muscle were studied and the IC50 of NaHS was calculated.The localization and expression of the subunits of KATP channels were determined by the methods of immunohistochemistry and Western blotting.RESULTS:WAS increased contractile activity of colonic strips.NaHS concentration-dependently inhibited the spontaneous contractions of strips from the SWAS and WAS rats.The IC50 of NaHS for longitudinal muscle ( LM) and circular muscle ( CM) of the WAS rats was 0.2033 mmol/L and 0.1438 mmol/L, significantly lower than those of the SWAS rats.Glibenclamide significantly in-creased the IC50 of NaHS for LM and CM from the SWAS and WAS rats.In both SWAS and WAS rat colon, Kir6.1, Kir6.2 and SUR2B were expressed on the plasma membrane of the smooth muscle cells.WAS treatment resulted in up-reg-ulation of the expression of Kir6.1 and SUR2B in the colon devoid of mucosa and submucosa.CONCLUSION: The in-creased expression of Kir 6.1 and SUR2B in colonic smooth muscle cells may be a defensive response to chronic WAS.H2 S donors may have potential clinical effect on treating chronic stress-induced colonic hypermotility.
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Objective: To observe the protective effect of ischemic post-conditioning on myocardial reperfusion injury with the potential mechanism in experimental rabbits. Methods: A total of 36 healthy New Zealand rabbits were divided into 6 groups:①Sham group,②Ischemic reperfusion control (CON) group,③Myocardial ischemic post-conditioning (MpostC) group,④Remote ischemic post-conditioning (RPostC) group,⑤MPostC+5-HD group,⑥RPostC+5-HD group.n=6 in each group. The ischemic reperfusion injury model was established by left ventricular descending artery occlusion for 45 min followed by reperfusion for 120 min. Bilateral external iliac artery was occluded for 5 min to induce the short skeletal muscle ischemia. The indexes of cardiac function and plasma CK , LDH activities were measured at baseline, end of ischemia and 1, 2 h after reperfusion respectively, the sizes of myocardial infarction (MI) were examined and compared among different groups. Results: ①Compared with CON group, the indexes of cardiac function were improved in MPostC and RPostC groups at 1, 2 h after reperfusion,P0.05. The MI ranges and areas in MPostC and RPostC groups were much less than that in CON group,P0.05. Conclusion: Classical ischemic post-conditioning and remote organ ischemic post-conditioning both have protective effect on myocardial reperfusion injury in experimental rabbit, which might be related to the activation of mitochondrial ATP-sensitive potassium channels.
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AIM:To investigate the roles of ATP-sensitive potassium ( KATP ) channels in high glucose-induced cardiac injury and the inhibitory effect of hydrogen sulfide ( H2 S) on the cardiomyocyte injury.METHODS:The expres-sion level of KATP channel protein was tested by Western blot.The cell viability was measured by CCK-8 assay.The number of apoptotic cells was observed by Hoechst 33258 nuclear staining.Mitochondrial membrane potential ( MMP) was exam-ined by JC-1 staining.RESULTS:After the H9c2 cells were treated with 35 mmol/L glucose ( high glucose, HG) for 1~24 h, the protein level of KATP channel was significantly reduced at 6 h, 9 h, 12 h and 24 h, reaching the minimum level at 12 h and 24 h.Pretreatment of the cells with 400μmol/L NaHS ( a donor of H2 S) prior to exposure to HG for 12 h con-siderably blocked the down-regulation of KATP channels induced by HG.Pretreatment of the cells with 100 μmol/L mito-chondrial KATP channel opener diazoxide, 50μmol/L non-selective KATP channel opener pinacidil or NaHS obviously inhibi-ted HG-induced injuries, leading to an increase in the cell viability, and decreases in the number of apoptotic cells and the MMP loss.Pretreatment with 100μmol/L mitochondrial KATP channel antagonist 5-hydroxydecanoic acid or 1 mmol/L non-selective KATP channel antagonist glibenclamide attenuated the above cardioprotective effects of NaHS.CONCLUSION:KATP channels mediate the inhibitory effect of H2 S on HG-induced cardiac injury.
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Daniellia oliveri stem bark is used traditionally by the people of Northern Ghana to manage pain. This study therefore sought to validate the antinociceptive property of an aqueous stem bark extract of Daniellia oliveri (DOE) using murine hot plate and paw pressure pain models as well as its antioxidant property. Groups of ICR mice were pre-treated with DOE (250, 500, 1000 or 2000 mg kg-1 , p.o), morphine (3 mg kg-1 , i.p), diclofenac (3 mg kg-1 , i.p) or normal saline (2 ml/kg) respectively for 0.5 - 1 h, prior to pain induction. Pain latency period were measured at 0.5 h intervals for 1.5 h. To establish the possible mode of analgesic activity, nociceptive activity of DOE was antagonized by naloxone (2 mg kg-1), glibenclamide (8mg kg-1), and theophylline (5mg kg1). The extract was screened for antioxidant property by its effect on DPPH radical scavenging activity. DOE in both pain models produced significant (P ≤ 0.001) dose and time - dependent antinociceptive effect comparable to morphine, and diclofenac. The antinociceptive effect of DOE was significantly (P ≤ 0.001) attenuated by naloxone, glibenclamide, and theophylline. DOE caused a concentration dependent percentage increase in DPPH radical scavenging activity. The aqueous stem bark extract of Daniellia oliveri therefore has antinociceptive and antioxidant effect with antinoception possibly mediated through activation of ATP-sensitive potassium channels, as well as opioidergic and adenosinergic receptor pathways.
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Objective To reveal the clinical features of children with transient neonatal diabetes mellitus (TNDM) in order to provide a basis for the TNDM treatment strategy formulation.Methods Four patients diagnosed as TNDM hospitalized in Beijing Children's Hospital Affiliated to Capital Medical University from Dec.2008 to Dec.2010 were chosen as research subjects.Their clinical data were analyzed retrospectively.Results The 4 patients diagnosed as TNDM started insulin therapy.Two cases of the 4 patients transferred from insulin to oral Sulfonylureas for 2-3 weeks after their conditions became steady.One patient was treated with Sulfonylureas successfully and the other one was partially effective with this therapy.After 2 to 3 years follow-up,3 cases remitted in 1 month after birth with no other severe complications,one case lost.Conclusions Infants with TNDM had unique clinical features.The patients develop diabetes in the first few weeks of life but go into remission in a few months.So the follow-up for those TNDM patient is very essential for clinical classification.Oral glibenclamide therapy seems highly effective and safe for some TNDM patients.
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0 05) group. Treatment with propofol or the combination of propofol and 5 HD delayed the onset of contracture during ischemia compared with control or 5 HD treatments for (6 4?2 1) min or (6 8?2 5) min vs (4 4?1 4) min or (4 2?1 6) min, respectively; P 0 05). The LVEDP in propofol or propofol plus 5 HD increased more slowly than in the control or 5 HD group. Maximal LVEDP occurred 17 min or 16 min,respectively after ischemia in the control group,whereas it occurred 20 and 22 min after ischemia in propofol and propofol plus 5 HD groups, respectively( P
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ATP sensitive potassium (K ATP ) channels widely expressed in many tissue and cell types including neurons are heteromultimers of sulfonylurea receptor (SUR) and inward rectifier K + channel (Kir6) subunits associated with 1∶1 stoichiometry as a tetramer (SUR/Kir6) 4. The activity of K ATP channels is modulated by intracellular ATP concentrations. Neuronal K ATP channels are involved in the mediation of glucose sensing and metabolic stress. Under physiological condition, they also possess important pathophysiological functions in acute brain ischemic and chronic neurodegenerative diseases.
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AIM To investigate whether ATP sensitive pota ss ium channels are involved in the protective effects of ischemic preconditioning on spinal cord in rabbits. METHODS Twenty seven male New Zealands white rabbits were randomly assigned to 3 groups (9 in each group):ischemia gro up(IC)、ischemic preconditioning group (IPC) and glibenclamide + ischemic precon ditioning group(G+I). In IC group, spinal cord ischemia was induced by an infrar enal aorta clamping for 20 min; IPC group underwent a 6 min ischemic preconditio ning followed by 30 min of reperfusion before the 20 min clamping; G+I group wer e administered glibenclamide (an ATP sensitive potassium channel blocker, 2 mg? kg -1 )intravenously 20 min before the ischemic preconditioning. Neurologic function was scored at 8,12,24 and 48 h after reperfusion. All animals were sa crificed at 48 h after reperfusion and the spinal cords (L 5～7 ) were remov ed for histopathologic study. RESULTS The neurologic function sco res in IPC group at each observe interval were higher than those in IC group and G+I group (P
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AIM: To investigate the protective effects and mechanisms of iptakalim hydrochloride(Ipt)on H_2O_2 induced neurotoxity. METHODS: Neurotoxity injury was induced by H_2O_2 in PC12 cells. The cell viability was tested by MTT assay. The glutamate released from PC12 cells was measured by HPLC combined with fluorescent detector analysis. Changes in the intracellular free Ca 2+ concentration ([Ca 2+ ]_i) were determined in fluo-3 AM loaded PC12 cells. RESULTS: Ipt (1, 10 and 100 ?mol?L -1 ) markedly mitigated H_2O_2-induced neurotoxity, 10 ?mol?L -1 Ipt inhibited the release of glutamate and the increase of [Ca 2+ ]_i induced by H_2O_2 .The protective effects was incompletely blocked by 5-HD which is a mitochondrial K_ ATP channels antagnist. CONCLUSION: Ipt provides neuroprotective effects on H_2O_2 induced cytoxixity in cultured PC12 cells and the protective effects may be partially related with mitochondrial KATP channels.
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A regulating mechanism of the ATP-sensitive potassium channels (KATP channels) is yet to fully explained. This study was carried out to investigate the effects of intracellular application of monocarboxylates (acetate, formate, lactate, and pyruvate) on KATP channels in isolated rabbit ventricular myocytes. Single channel currents of KATP channels were recorded using the excised inside-out or permeabilized attached (open-cell) patch-clamp technique at room temperature. Intracellular application of acetate, formate and pyruvate led to an inhibition of channel activity, whereas intracellular application of lactate increased channel activity. These effects were reversible upon washout. Analysis of single channel kinetics showed that monocarboxylates did not affect open-time constant and close-time constant. These results suggest that monocarboxylates participate in modulating KATP channels activity in cardiac cells and that modulation of KATP channels activity may resolve the discrepancy between the low Ki in excised membrane patches and high levels of intracellular ATP concentration during myocardial ischemia or hypoxia.
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Adenosine Triphosphate , Hypoxia , KATP Channels , Kinetics , Lactic Acid , Membranes , Muscle Cells , Myocardial Ischemia , Patch-Clamp Techniques , Pyruvic AcidABSTRACT
Objective To observe the delayed cardioprotective effect of the extract of Gingkgo biloba leaves(EGb761)and its possible mechanisms in rats.Methods Myocardial ischemia-reperfusion(I/R)injury was induced by 30 min of global ischemia and 30 min of reperfusion in isolated rat hearts.Heart rate(HR),coronary flow(CF),left ventricular pressure(LVP),and its first derivatives(+dp/dtmax)were recorded,and the releasing content of creatine kinase(CK),contents of malondialdehyde(MDA)and nitric oxide(NO)in myocardial tissues were measured.Results Single ig EGb761(50 or 100 mg/kg)at 24 h before I/R were done could significantly attenuate the damage of cardiac function(LVP and +dp/dtmax)and the lowering of NO level in myocardial tissues,and inhibit the increasing in CK release and MDA level induced by I/R in myocardial tissues.The delayed cardioprotective effects of EGb761 were markedly inhibited by pretreatment with L-NAME(5 mg/kg),an inhibitor of NO synthase,or HMR1883(3 mg/kg),an antagonist of sarcolemmal ATP-sensitive potassium channels(sarcKATP).Conclusion Pretreatment with EGb761 could protect against I/R-induced myocardial injury in rats,and the delayed cardioprotection of EGb761 may be related to increasing in NO production and opening of sarcKATP.
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ATP sensitive potassium channels (K ATP ) have been thought to be a mediator of cardioprotection. Recent pharmacologic and molecular biology studies show the protective effects of K ATP openers are not dependent of action potential shortening and cardiodepressant effects, but mediated by preservation of mitochondrial function, which suggests a role for intracellular mitochondrial K ATP (mito K ATP ). The mechanism by opening mito K ATP produces cardioprotection is less clearer, however, it is thought that a beneficial effect may occur as the result of K + entry and intramitochondrial depolarization. This effect would reduce mitochondrial calcium overload and cause matrix swelling, which are shown to enhance ATP synthesis and stimulate mitochondrial respiration.