Role Of ATP-sensitive Potassium Channels Research Articles

Изменение вклада К АТФ -каналов в поддержание базального тонуса и дилатацию пиальных артериальных сосудов крыс после ишемии

The changes in the contribution of ATP-sensitive potassium channels (KATP) in basal tone and acetylcholine (ACh) mediated dilation of pial arterial vessels after global cerebral ischemia (2VO + hypo model) were studied in Wistar rats. Vascular examination was performed 7, 14 and 21 days after ischemia. False- operated rats served as a control. The change in the contribution of KATP channels in basal tone was assessed using intravital microphotography. The number of vessels that constricted in response to the effect of the KATP channel blocker (glibenclamide, 10 μM) was assessed. The change in the contribution of channels in vascular dilatation was assessed by comparing the number and degree of arterial dilatation in response to ACh (10-7 M, 5 min) before and after the use of a KATP channel blocker. It was found that ischemia decreases the role of ATP-sensitive potassium channels in basal tone of the pial arterial vessels for 14 days after ischemic exposure. At the same time, the contribution of KATP - channels in the ACh mediated dilator reactions of pial vessels decreases. And by 21 days after ischemia, KATP channels do not participate in the dilator response to ACh.

Protective effect of modafinil on skin flap survival in the experimental random-pattern skin flap model in rats: The role of ATP-sensitive potassium channels and nitric oxide pathway

Background The brain-stimulating agent modafinil acts through nitric oxide (NO) and adenosine triphosphate (ATP)-sensitive potassium (KATP) channels, involved in the skin flap survival (SFS). The main aim of this study was to investigate the efficacy of modafinil on SFS in rats through the involvement of NO pathway and KATP channels. Methods Using controlled experiment study design, we enrolled a sample of Wistar male rats. Different doses of modafinil (10, 25, 50, and 100 mg/kg) were injected intraperitoneally (i.p.) before the surgery. L-NAME (non-selective nitric oxide synthase [NOS] inhibitor), aminoguanidine (inducible NOS inhibitor), and 7-nitroindazole (neuronal NOS inhibitor) were administered prior to modafinil. The role of KATP channels was determined by coadministering glibenclamide (KATP channel blocker) or cromakalim (KATP channel opener) with modafinil. The predictor variables were administration of different doses of modafinil, and the coadministration of modafinil with L-NAME, aminoguanidine, 7-nitroindazole, glibenclamide, and cromakalim. The main outcome variables included the percentage of necrotic area (PNA) in flap tissues, histopathological results, vascular endothelial growth factor (VEGF) immunohistochemical (IHC) staining, and nitrite concentrations. Appropriate statistics were computed considering p-value ≤ 0.05 significant. Results Modafinil 25 mg/kg was the most effective dose (PNA: 26 [95% CI: 19–33]) vs. control (PNA: 81 [95% CI: 71–92]) (p< 0.001). All NOS inhibitors significantly reversed the protective effect of modafinil (p< 0.001). Non-effective dose of cromakalim had a synergistic effect with the sub-effective dose of modafinil (10 mg/kg), while glibenclamide reversed the effect of modafinil 25 mg/kg (p< 0.001). Conclusions Modafinil increases SFS mediated by NO pathway and KATP channels, which could therefore be a target to improve SFS. The brain-stimulating agent modafinil acts through nitric oxide (NO) and adenosine triphosphate (ATP)-sensitive potassium (KATP) channels, involved in the skin flap survival (SFS). The main aim of this study was to investigate the efficacy of modafinil on SFS in rats through the involvement of NO pathway and KATP channels. Using controlled experiment study design, we enrolled a sample of Wistar male rats. Different doses of modafinil (10, 25, 50, and 100 mg/kg) were injected intraperitoneally (i.p.) before the surgery. L-NAME (non-selective nitric oxide synthase [NOS] inhibitor), aminoguanidine (inducible NOS inhibitor), and 7-nitroindazole (neuronal NOS inhibitor) were administered prior to modafinil. The role of KATP channels was determined by coadministering glibenclamide (KATP channel blocker) or cromakalim (KATP channel opener) with modafinil. The predictor variables were administration of different doses of modafinil, and the coadministration of modafinil with L-NAME, aminoguanidine, 7-nitroindazole, glibenclamide, and cromakalim. The main outcome variables included the percentage of necrotic area (PNA) in flap tissues, histopathological results, vascular endothelial growth factor (VEGF) immunohistochemical (IHC) staining, and nitrite concentrations. Appropriate statistics were computed considering p-value ≤ 0.05 significant. Modafinil 25 mg/kg was the most effective dose (PNA: 26 [95% CI: 19–33]) vs. control (PNA: 81 [95% CI: 71–92]) (p< 0.001). All NOS inhibitors significantly reversed the protective effect of modafinil (p< 0.001). Non-effective dose of cromakalim had a synergistic effect with the sub-effective dose of modafinil (10 mg/kg), while glibenclamide reversed the effect of modafinil 25 mg/kg (p< 0.001). Modafinil increases SFS mediated by NO pathway and KATP channels, which could therefore be a target to improve SFS.

ATP-Sensitive Potassium Channels Mediate the Cardioprotective Effect of Panax notoginseng Saponins against Myocardial Ischaemia-Reperfusion Injury and Inflammatory Reaction.

Inflammatory response during myocardial ischemia reperfusion injury (MIRI) is essential for cardiac healing, while excessive inflammation extends the infarction and promotes adverse cardiac remodeling. Understanding the mechanism of these uncontrolled inflammatory processes has a significant impact during the MIRI therapy. Here, we found a critical role of ATP-sensitive potassium channels (KATP) in the inflammatory response of MIRI and its potential mechanism and explored the effects of Panax Notoginseng Saponins (PNS) during this possess. Rats underwent 40 min ischemia by occlusion of the left anterior descending (LAD) coronary artery and 60 min of reperfusion. PNS was treated at the corresponding time point before operation; 5-hydroxydecanoate (5-HD) and glybenclamide (Gly) (or Nicorandil (Nic)) were used as pharmacological blocker (or nonselective opener) of KATP. Cardiac function and pathomorphology were evaluated and a set of molecular signaling experiments was tested. KATP current density was measured by patch-clamp. Results revealed that in MIRI, PNS pretreatment restored cardiac function, reduced infarct size, and ameliorated inflammation through KATP. However, inhibiting KATP by 5-HD and Gly significantly reversed the effects, including NLRP3 inflammasome and inflammatory mediators IL-6, MPO, TNF-α, and MCP-1. Moreover, PNS inhibited the phosphorylation and nuclear translocation of NF-κB in I/R myocardium when the KATP was activated. Importantly, PNS promoted the expression of subunits and activation of KATP. The study uncovered KATP served as a new potential mechanism during PNS modulating MIRI-induced inflammation and promoting injured heart recovery. The manipulation of KATP could be a potential therapeutic approach for MIRI and other inflammatory diseases.

Cardioprotective effect of hemin in isoprenaline-induced myocardial infarction: role of ATP-sensitive potassium channel and endothelial nitric oxide synthase.

Ischemic heart disease is a common cardiac health problem. Despite the significant advances in prevention and treatment of this disorder, its incidences and complications are very serious. So, the search for more antioxidants and anti-inflammatory agents with cardioprotective effects is an urgent task. We aimed to evaluate the effects of a heme oxygenase 1 (HO1) inducer, hemin (HEM), on isoprenaline (ISO)-induced myocardial damage. Forty-five Wistar albino rats were used. Animals were treated with HEM (25mg/kg/day) i.p. for 5days and injected with ISO (150mg/kg/day) i.p. on 4th and 5th day of the experiment. Detection of the role of ATP-sensitive potassium channel (KATP ) was performed by administration of glibenclamide (GP) (5mg/kg/day) orally 2h before HEM. Moreover, the role of endothelial nitric oxide synthase (eNOS) was detected by coadministration of Nitro- ω-L-arginine (L-NNA) (25mg/kg/day) for 5days. The ISO group showed increase in heart weight, cardiac enzymes, tumor necrosis factor alpha (TNFα), and malondialdehyde (MDA) with decrease in reduced glutathione (GSH), HO1, and total antioxidant capacity (TAC). In addition, there were increases in Bcl-2 associated X protein (Bax) and cleaved caspase-3, but decreases in B-cell lymphoma-2 (Bcl-2) and eNOS. Moreover, the histopathological examination ofthe ISO group showed degeneration of the cardiac muscle fibers and marked infiltration of the inflammatory cells. The biochemical and histopathological changes induced by ISO were markedly ameliorated in the HEM plus ISO group. This protective effect was diminished with coadministration of GP or L-NNA; thus, KATP and eNOS might mediate HEM cardioprotection.

Role of ATP-sensitive potassium channels and inflammatory response of basilar artery smooth muscle cells in subarachnoid hemorrhage of rabbit and immune-modulation by shikonin

ObjectiveTo investigate the role of inflammatory response, oxidative damage and changes of ATP-sensitive potassium channels (sKATP) in basilar artery (BA) smooth muscle cells (SMCS) of rabbits in subarachnoid hemorrhage (SAH) model. MethodsTime course studies on inflammatory response by real-time PCR, oxidative process and function of isolated basilar artery after SAH in New Zealand White rabbits were performed. Basilar artery smooth muscle cells (BASMCs) in each group were obtained and whole-cell patch-clamp technique was applied to record cell membrane capacitance and KATP currents. The morphologies of basal arteries were analyzed. Protective effect of shikonin were also determine by same parameters. ResultsInflammatory cytokines levels were highest at 24h compare to 72h after SAH whereas the oxidative damage and cell death marker were at highest peak at 72h. Oxidative damage peak coincided with significant alterations in cell membrane capacitance, KATP currents and morphological changes in basilar arteries. Shikokin pretreatment attenuated early inflammatory response at 24h and associated oxidative damage at 72h. Finally, shikonin attenuated morphological changes in basilar arteries and dysfunction. ConclusionCurrents of ATP-sensitive potassium channels in basilar smooth muscle cells decreased after SAH by putative oxidative modification from immediate inflammatory response and can be protected by shikonin pretreatment.

Role of ATP-Sensitive Potassium Channel (KATP) and eNOS in Mediating the Protective Effect of Nicorandil in Cyclophosphamide-Induced Cardiotoxicity.

Cyclophosphamide (CP) is a widely used chemotherapeutic agent but its clinical usefulness is challenged with different forms of toxicities. No studies have evaluated the possible protective effect of nicorandil (NIC) in CP-induced cardiotoxicity. Our study aimed to investigate this effect by using NIC (3mg/kg/day) orally for 5days, in the presence or absence of cardiotoxicity induced by intraperitoneal (i.p.) injection of CP (150mg/kg) on 4th and 5th days. We confirmed the role of ATP-sensitive potassium channel (KATP) by coadministration of glibenclamide (GP) (5mg/kg/day) 2h before NIC (3mg/kg/day) for 5days. Moreover, the role of endothelial nitric oxide synthase (eNOS) was confirmed by coadministration of nitro-ω-L-arginine (L-NNA) (25mg/kg/day) for 5days. Results showed that CP succeeded in induction of cardiotoxicity which manifested by a significant increase in heart weights, creatine kinase-MB (CK-MB), lactate dehydrogenase (LDH), troponin I, cardiac tissue malondialdehyde (MDA), tumor necrosis factor alpha (TNF-α), interleukin 1β (IL1 β), and caspase-3 levels. Furthermore, CP group showed toxic histopathological changes of marked cardiac damage in addition to a significant decrease in total antioxidant capacity (TAC), superoxide dismutase (SOD), eNOS gene expression, and B cell lymphoma 2 (Bcl2) immunoexpression. NIC succeeded in reversing CP-induced cardiotoxicity by its potassium channel opening effect, stimulating eNOS gene expression, anti-inflammatory, antiapoptotic, and antioxidant properties. Coadministration of GP or L-NNA could diminish the protective effect of NIC. This proves the important role of KATP and eNOS in mediating such protection.

Hyperglycemia induces mechanical hyperalgesia and depolarization of the resting membrane potential of primary nociceptive neurons: Role of ATP-sensitive potassium channels

Cumulating data suggests that ion channel alterations in nociceptive neurons might be involved in the development of diabetic painful neuropathy. In the present study we investigated the involvement of ATP-sensitive potassium (K+ATP) channels in the acute effect of high glucose solution in vitro and in vivo. High glucose concentrations depolarized cultured nociceptive neurons and depolarization was blocked by the K+ATP opener, diazoxide or by insulin. Glucose injection at the rat dorsal root ganglia (L5) resulted in acute mechanical hyperalgesia that was blocked by diazoxide. Mannitol injection indicates that osmolarity changes are not responsible for glucose effect. Therefore, this study suggests that K+ATP channels expressed in peripheral sensory neurons might be involved in the development of diabetic painful neuropathy. Since sulfonylureas, that act by blocking K+ATP are used for diabetes treatment, it is important to evaluate the possible side effects of such drugs at primary sensory neurons.

Role of ATP-sensitive potassium channels on hypoxic pulmonary vasoconstriction in endotoxemia

BackgroundATP-regulated potassium channels (KATP) regulate pulmonary vascular tone and are involved in hypoxic pulmonary vasoconstriction (HPV). In patients with inflammation like sepsis or ARDS, HPV is impaired, resulting in a ventilation-perfusion mismatch and hypoxia. Since increase of vascular KATP channel Kir6.1 has been reported in animal models of endotoxemia, we studied the expression and physiological effects of Kir6.1 in murine endotoxemic lungs. We hypothesized that inhibition of overexpressed Kir6.1 increases HPV in endotoxemia.MethodsMice (C57BL/6; n = 55) with (n = 27) and without (n = 28) endotoxemia (35 mg/kg LPS i.p. for 18 h) were analyzed for Kir6.1 gene as well as protein expression and HPV was examined in isolated perfused mouse lungs with and without selective inhibition of Kir6.1 with PNU-37883A. Pulmonary artery pressure (PAP) and pressure-flow curves during normoxic (FiO2 0.21) and hypoxic (FiO2 0.01) ventilation were obtained. HPV was quantified as the increase in perfusion pressure in response to hypoxic ventilation in mmHg of baseline perfusion pressure (ΔPAP) in the presence and absence of PNU-37883A.ResultsEndotoxemia increases pulmonary Kir6.1 gene (+ 2.8 ± 0.3-fold) and protein expression (+ 2.1 ± 0.3-fold). Hypoxia increases HPV in lungs of control animals, while endotoxemia decreases HPV (∆PAP control: 9.2 ± 0.9 mmHg vs. LPS: 3.0 ± 0.7 mmHg, p < 0.05, means ± SEM). Inhibition of Kir6.1 with 1 μM PNU-37883A increases HPV in endotoxemia, while not increasing HPV in controls (∆PAP PNU control: 9.3 ± 0.7 mmHg vs. PNU LPS: 8.3 ± 0.9 mmHg, p < 0.05, means ± SEM).ConclusionEndotoxemia increases pulmonary Kir6.1 gene and protein expression. Inhibition of Kir6.1 augments HPV in murine endotoxemic lungs.

The Role of ATP-Sensitive Potassium Channels and Nitric Oxide in the Protective Effect of Preconditioning of the Brain

Objective. The role of ATP-dependent potassium (K+ ATP) channels in the neuroprotective effect of ischemic (IPre) and pharmacological (PPre) preconditioning and changes in blood levels of nitric oxide (NO) metabolites were studied in conditions of cerebral ischemia. Materials and methods. Ischemic stroke (IS) was modeled in male rats (n = 86) by electrocoagulation of a branch of the middle cerebral artery (MCA). The nonselective K+ ATP channel blocker glibenclamide and the K+ ATP channel activator diazoxide were used. IPre and PPre were performed one day before MCA occlusion. Blood concentrations of NO, nitrates (NO3 –) and nitrites (NO2 –) were determined in experimental animals at 5, 24, and 72 h after MCA occlusion. Results. IPre decreased the lesion zone by 37% (p < 0.05), while prior administration of glibenclamide countered the action of IPre. The protective effect of PPre was analogous to that of IPre. Decreases in blood levels of oxygenated R-conformers of hemoglobin-bound NO (Hb-NO) were seen 5 h after MCA occlusion, with an inversely proportional increase in the concentration of nonoxygenated T-conformers; there were also increases in NO3 – and NO2 – concentrations. NO3 – and NO2 – levels showed normalization by one day after MCA occlusion, along with changes in the concentrations of Hb-NO complexes – R-conformers dominated, while the blood level of T-conformers reached a minimum. Furthermore, by 24 h there was a correlation between blockade of K+ ATP channels and decreases in serum NO3 – and NO2 – levels (p < 0.03). Conclusions. The neuroprotective effect of preconditioning was due to activation of K+ ATP channels. Analysis of blood levels of NO metabolites in rats with IS showed that Hb-NO complexes in the R-conformation stored and carried NO to the tissues, releasing NO on occurrence of the R → T transition in ischemic conditions.

Role of ATP-Sensitive Potassium Channels in Remote Ischemic Preconditioning Induced Tissue Protection.

Remote ischemic preconditioning (RIPC) is an innovative treatment strategy that alleviates ischemia-reperfusion injury, whereby short episodes of regional ischemia and reperfusion delivered to remote organs including hind limb, kidney and intestine, and so on provide protection to the heart. The RIPC is known to reduce infarct size, serum levels of cardiac enzymes, and myocardial dysfunction in various animal species as well as in patients. There have been a large number of studies suggesting that the ATP-sensitive potassium channels (KATP channel) play a significant role as a mediator or end effector in RIPC. The present review discusses the role of KATP channels and possible mechanisms in RIPC-induced cardioprotection.

1078 Methylglyoxal Reduces Gastric Tone in Rats: Role of ATP-Sensitive Potassium Channel

1078 Methylglyoxal Reduces Gastric Tone in Rats: Role of ATP-Sensitive Potassium Channel

A role for ATP-sensitive potassium channels in the anticonvulsant effects of triamterene in mice

There are reports indicating that diuretics including chlorothiazide, furosemide, ethacrynic acid, amiloride and bumetanide can have anticonvulsant properties. Intracellular acidification appears to be a mechanism for the anticonvulsant action of some diuretics. This study was conducted to investigate whether or not triamterene, a K+-sparing diuretic, can generate protection against seizures induced by intravenous or intraperitoneal pentylenetetrazole (PTZ) models. And to see if, triamterene can withstand maximal electroshock seizure (MES) in mice. We also investigated to see if there is any connection between triamterene's anti-seizure effect and ATP-sensitive K+ (KATP) channels. Five days triamterene oral administration (10, 20 and 40mg/kg), significantly increased clonic seizure threshold which was induced by intravenous pentylenetetrazole. Triamterene (10, 20 and 40mg/kg) treatment also increased the latency of clonic seizure and decreased its frequency in intraperitoneal PTZ model. Administration of triamterene (20mg/kg) also decreased the incidence of tonic seizure in MES-induced seizure. Co-administration of a KATP sensitive channel blocker, glibenclamide, in the 6th day, 60min before intravenous PTZ blocked triamterene's anticonvulsant effect. A KATP sensitive channel opener, diazoxide, enhanced triamterene's anti-seizure effect in both intravenous PTZ or MES seizure models. At the end, triamterene exerts anticonvulsant effect in 3 seizure models of mice including intravenous PTZ, intraperitoneal PTZ and MES. The anti-seizure effect of triamterene probably is induced through KATP channels.

Role of ATP-sensitive potassium channels in modulating nociception in rat model of bone cancer pain

Bone cancer pain is a major clinical problem and remains difficult to treat. ATP-sensitive potassium (KATP) channels may be involved in regulating nociceptive transmission at the spinal cord level. We determined the role of spinal KATP channels in the control of mechanical hypersensitivity in a rat model of bone cancer pain. The rat model of bone cancer pain was induced by implanting rat mammary gland carcinoma cells (Walker256) into the tibias. KATP modulators (pinacidil and glibenclamide) or the specific Kir6.2-siRNA were injected via an intrathecal catheter. The mechanical withdrawal threshold of rats was tested using von Frey filaments. The Kir6.2 mRNA and protein levels were measured by quantitative PCR and western blots, respectively. Intrathecal injection of pinacidil, a KATP channel opener, significantly increased the tactile withdrawal threshold of cancer cell-injected rats in a dose-dependent manner. In contrast, intrathecal delivery of glibenclamide, a KATP channel blocker, or the specific Kir6.2-siRNA significantly reduced the tactile withdrawal threshold of cancer cell-injected rats. The mRNA and protein levels of Kir6.2 in the spinal cord of cancer cell-injected rats were significantly lower than those in control rats. Our findings suggest that the KATP channel expression level in the spinal cord is reduced in bone cancer pain. Activation of KATP channels at the spinal level reduces pain hypersensitivity associated with bone cancer pain.

Relationship Between Mitochondrial Matrix Volume and Cellular Volume in Response to Stress and the Role of ATP-Sensitive Potassium Channel

Cardiac myocytes demonstrate significant swelling and associated reduced contractility in response to stress that is prevented by the ATP-sensitive potassium channel opener, diazoxide (DZX) via an unknown mechanism. One proposed mechanism of cardioprotection is mitochondrial matrix swelling. To establish the relationship between mitochondrial and cellular volume during stress, this study examined the effect of DZX on mitochondrial volume. Isolated mouse mitochondria were exposed to the following solutions: Tyrode, isolation buffer, cardioplegia (CPG)±DZX±ATP-sensitive potassium channel inhibitor, 5-hydroxydecanoate, and metabolic inhibition (MI) ± DZX ± 5-hydroxydecanoate. Mitochondrial volume was measured. DZX resulted in significant mitochondrial swelling (P<0.0001 versus Tyrode). MI and CPG resulted in significant mitochondrial swelling compared with baseline volume. The addition of DZX did not alter the response of mitochondrial volume to CPG (P=0.912) but increased swelling in response to MI (P=0.036). The addition of 5-hydroxydecanoate to MI + DZX or CPG+DZX significantly reduced mitochondrial swelling (P<0.003 MI+DZX versus MI + DZX + 5HD; P<0.001 CPG+DZX versus CPG + DZX + 5HD). Both cellular and mitochondrial volume increased during exposure to MI and CPG. DZX did not alter mitochondrial volume during CPG; however, it was associated with an increase in mitochondrial volume during MI. 5-Hydroxydecanoate reduced mitochondrial volume during exposure to both stresses with DZX, supporting a role for a mitochondrial ATP-sensitive potassium channel in the mechanism of cardioprotection by DZX.

Congenital hyperinsulinism: Clinical and molecular analysis of a large Italian cohort

Congenital hyperinsulinism (CHI) is a genetic disorder characterized by profound hypoglycemia related to an inappropriate insulin secretion. It is a heterogeneous disease classified into two major subgroups: “channelopathies” due to defects in ATP-sensitive potassium channel, encoded by ABCC8 and KCNJ11 genes, and “metabolopathies” caused by mutation of several genes (GLUD1, GCK, HADH, SLC16A1, HNF4A and HNF1A) and involved in different metabolic pathways. To elucidate the genetic etiology of CHI in the Italian population, we conducted an extensive sequencing analysis of the CHI-related genes in a large cohort of 36 patients: Twenty-nine suffering from classic hyperinsulinism (HI) and seven from hyperinsulinism–hyperammonemia (HI/HA). Seventeen mutations have been found in fifteen HI patients and five mutations in five HI/HA patients. Our data confirm the major role of ATP-sensitive potassium channel in the pathogenesis of Italian cases (~70%) while the remaining percentage should be attributed to other. A better knowledge of molecular basis of CHI would lead to improve strategies for genetic screening and prenatal diagnosis. Moreover, genetic analysis might also help to distinguish the two histopathological forms of CHI, which would lead to a clear improvement in the treatment and in genetic counseling.

Role of ATP-sensitive potassium channel in spinal dorsal horn neurons in hyperalgesia after thoracotomy in rats

Objective To evaluate the role of ATP-sensitive potassium (KATP) channel in spinal dorsal horn neurons in hyperalgesia after thoracotomy in rats.Methods Twenty-eight Sprague-Dawley rats,aged 7-9 weeks,weighing 250-350 g,in which intrathecal catheters were successfully implanted without complications on 14th day after chronic post-thoracotomy pain was induced,were randomly divided into 4 groups (n =7 each):control group,the solvent dimethyl sulfoxide (DMSO) group,KATP channel opener pinacidil group (group P) and KATP channel blocker glibenclamide group (group G).10％ DMSO 10 μl,pinacidil 10 μg/10 μl and glibenclamide 50μg/10μ1 were injected intrathecally in groups DMSO,P and G at 5 day after the intrathecal catheter was implanted,respectively.Paw withdrawal threshold to von Frey filament stimulation was measured before intrathecal administration and at 10,30 and 60 min after intrathecal administration and the acetone test was performed.Coldinduced pain threshold was measured.Results There was no significant difference in paw withdrawal threshold to yon Frey filament stimulation at each time point among the four groups (P ＞ 0.05).Compared with C and DMSO groups,cold-induced pain threshold was significantly increased in group P and decreased in group G (P ＜ 0.05).There was no significant difference in cold-induced pain threshold between C and DMSO groups (P ＞ 0.05).Conclusion KATP channel in spinal dorsal horn neurons is involved in the maintenance of hyperalgesia after thoracotomy in rats. Key words: Hyperalgesia ; KATP channels ; Pain, postoperative

Role of ATP sensitive potassium channel in protective effects of post-conditioning with hydrogen sulfide against hepatic ischemia-reperfusion injury in rats

Objective To investigate the role of ATP sensitive potassium (KATP ) channel in protective effects of post-conditioning with hydrogen sulfide against hepatic ischemia-reperfusion (I/R) injury in rats.Methods Thirty adult male SD rats weighing 220-250 g were randomly divided into 5 groups ( n =6 each):sham operation gorup (group S) ; hepatic I/R group; NaHS group; glibenclamide + NaHS group (group G) and 5-hydroxydecanoate (5-HD) + NaHS group (group 5-HD).Hepatic ischemia was produced by 60 min occlusion of left and middle lobe blood flow (about 70％ of the whole liver blood flow) followed by 6 h reperfusion in groups I/R,NaHS,G and 5-HD.NaH S 28 μmol/kg was administered intraperitoneally (IP) at 5 min before reperfusion in groups NaHS,G and 5-HD.Glibenclamide 6 mg/kg and 5-HD 10 mg/kg (KATP channel blockers) were administered IP at 5 min before IP NaHS in groups G and 5-HD respectively.Blood samples were collected at the end of 6 h of reperfusion for measurement of ALT and AST activities and liver specimens were obtained for microscopic examination and measurement of TNF-α content and MPO activity.Results Liver I/R significantly increased ALT,AST and MPO activities and TNF-α concentration in group I/R as compared with group S.NaHS administered at 5 min before reperfusion significantly attenuated hepatic I/R injury.Glibenclamide and 5-HD administered before NaHS could block the protective effect of NaHS against hepatic I/R injury.Conclusion Hydrogen sulfide postconditioning can protect the liver from I/R injury by activating KATP channel. Key words: KATP channels; Hydrogen sulfide; Reperfusion injury; Livers

The role of ATP-sensitive potassium channels on DMT1-mediated ferrous iron uptake in SK-N-SH cells

Background Elevated iron accumulation has been reported in the substantia nigra (SN) in Parkinson’s disease (PD). Our previous study observed that increased levels of the iron importer divalent metal transporter 1 (DMT1) were involved in this nigral iron accumulation and dopaminergic neurons loss in PD. The iron transport function of DMT1 is also related to the membrane potential level, which increases with hyperpolarization of the cell membrane. Activation of ATP-sensitive potassium (KATP) channels, which could induce hyperpolarization of nigral dopaminergic neurons, is reported to be involved in the selective loss of these neurons in PD. The present study is to investigate whether activation of KATP channels could change the iron uptake function of DMT1. Methods DiBAC4(3) and calcein were used to detect membrane potential and ferrous iron influx. Intracellular iron concentration was measured using an inductively coupled plasma (ICP-2) detector. Mitochondrial transmembrane potential (ΔΨm) and reactive oxygen species (ROS) were measured by flow cytometry using rhodamine123 and H2DCF-DA. Results (1) When treated with diazoxide, a novel KATP channel opener, the membrane potential of SK-N-SH cells showed hyperpolarization. (2) The influx of ferrous iron and the intracellular iron levels were observed dramatically increased when the cells were co-incubated with diazoxide and ferrous iron, resulting in a decreased ΔΨm and an elevated level of ROS production. (3) When treated with diazoxide, cells with DMT1 knockdown showed decreased ferrous iron influx compared with the vector control. (4) When treated with diazoxide, cells overexpressed of SUR1 and Kir6.2 showed increased ferrous iron influx compared with the vector control, which induced a decrease in ΔΨ ma nd an increase in ROS production. Conclusion These results suggest that the activation of the KATP channels could enhance DMT1-mediated ferrous iron uptake, leading to increase intracellular oxidative stress.

The role of ATP-sensitive potassium channel on acute urinary retention and subsequent catheterization in the rat

We investigated the role of K ATP channel on acute urinary retention (AUR) induced bladder dysfunction. Eight-week-old female Sprague–Dawley rats were divided into seven groups: a sham-operated control group, an AUR group, and five AUR groups treated with: two different K ATP channel openers namely nicorandil (3 or 10 mg/kg), or cromakalim (100 or 300 μg/kg), or one K ATP channel inhibitor namely glibenclamide (5 mg/kg). The drugs were administered 30 min before induction of AUR. After the urethra was obstructed with a clip, AUR was induced by intravesical infusion of 2.5 ml of saline via cystostomy. Following a 30 min obstruction the bladder was allowed to drain with a catheter in place for 60 min with real-time monitoring of intravesical pressure and blood flow. After the experimental period, the bladder function was assessed, using organ bath techniques (carbachol and 100 mM KCl). AUR increased the intravesical pressure and decreased the blood flow. The subsequent catheterization decreased the intravesical pressure and increased the blood flow. AUR group reduced significantly the contractile responses to both carbachol and KCl compared with the control group. Nicorandil and cromakalim but not glibenclamide prevented the bladder dysfunction after AUR suggesting that K ATP channel openers may prevent the bladder dysfunction caused by AUR and subsequent catheterization.

Hydrogen Sulfide Prevents Ethanol-Induced Gastric Damage in Mice: Role of ATP-Sensitive Potassium Channels and Capsaicin-Sensitive Primary Afferent Neurons

The aim of this study was to evaluate the protective effect of hydrogen sulfide (H(2)S) on ethanol-induced gastric lesions in mice and the influence of ATP-sensitive potassium (K(ATP)) channels, capsaicin-sensitive sensory afferent neurons, and transient receptor potential vanilloid (TRPV) 1 receptors on such an effect. Saline and L-cysteine alone or with propargylglycine, sodium hydrogen sulfide (NaHS), or Lawesson's reagent were administrated for testing purposes. For other experiments, mice were pretreated with glibenclamide, neurotoxic doses of capsaicin, or capsazepine. Afterward, mice received L-cysteine, NaHS, or Lawesson's reagent. After 30 min, 50% ethanol was administrated by gavage. After 1 h, mice were sacrificed, and gastric damage was evaluated by macroscopic and microscopic analyses. L-cysteine, NaHS, and Lawesson's reagent treatment prevented ethanol-induced macroscopic and microscopic gastric damage in a dose-dependent manner. Administration of propargylglycine, an inhibitor of endogenous H(2)S synthesis, reversed gastric protection induced by L-cysteine. Glibenclamide reversed L-cysteine, NaHS, or Lawesson's reagent gastroprotective effects against ethanol-induced macroscopic damage in a dose-dependent manner. Chemical ablation of sensory afferent neurons by capsaicin reversed gastroprotective effects of L-cysteine or H(2)S donors (NaHS or Lawesson's reagent) in ethanol-induced macroscopic gastric damage. Likewise, in the presence of the TRPV1 antagonist capsazepine, the gastroprotective effects of L-cysteine, NaHS, or Lawesson's reagent were also abolished. Our results suggest that H(2)S prevents ethanol-induced gastric damage. Although there are many mechanisms through which this effect can occur, our data support the hypothesis that the activation of K(ATP) channels and afferent neurons/TRPV1 receptors is of primary importance.