[Interventional effects of activating SUR2B/Kir6.1-type KATP channels on renal cells injury and its mechanisms].

Objective: To investigate the interventional effects of a new SUR2B/Kir6.1-type KATP Channel opener iptakalim on injury renal cells (the renal glomerular endothelial, mesangial and tubular epithelial cells) and its mechanisms. Methods: ①Experimental protocol: control: the cells were treated with with 0 mg/L uric acid for 24 h; model: the cells were treated with with 1 200 mg/L uric acid for 24 h; pretreatment with iptakalim: the cells were pretreated with 0.01,0.1,1,10,100 µmol/L iptakalim for 24 h prior to treatment with 1 200 mg/L uric acid for 24 h; pretreatment with glibenclamide: the cells were preincubated with/without 10 µmol/L glibenclamide for 1 h and then treated with 10 µmol/L iptakalim for 24 h followed by incubation with 1 200 mg/L uric acid for another 24 h. ②The cell viability was measured by MTT assay and flow cytometry; the protein expressions of Kir6.1 and SUR2B and nuclear translocation were detected by immunostaining; the protein expressions of Kir6.1 and SUR2B were determined by Western blot analysis; adhesion of mononuclear cells to endothelial cells were tested by fluorimetric assay; the content of MCP-1 was measured by enzyme linked-immunosorbent assay (ELISA). Results: The renal glomerular endothelial, mesangial and tubular epithelial cells were exposed to 1 200 mg/L uric acid for 24 h. Compared with the control group, 1 200 mg/L uric acid decreased the cell survival rates significantly (P＜0.01, P＜0.01, P＜0.01). Compared with the model group, pretreatment with 0.1, 1, 10, 100 µmol/L iptakalim could remarkably alleviate cellular damages of glomerular endothelium, mesangium cells induced by uric acid (P＜0.05, P＜0.01, P＜0.01, P＜0.01). The KATP channel blocker could clearly reduce survival rates of the renal glomerular endothelial, mesangial cells(P＜0.01) and markedly reverse the inhibitory effects of iptakalim on cell death (P＜0.05, P＜0.01), no obvious difference in comparison with the model group (P＞0.05). Compared with the model group, pretreatment with 10, 100 µmol/L iptakalim could notably attenuate cellular damages of tubular epithelial cells induced by uric acid (P＜0.05, P＜0.05). The KATP channel blocker could obviously damage the tubular epithelial cells (P＜0.01), no obvious difference in comparison with the model group (P＞0.05). Compared with control group, exposure of renal tubular epithelial, mesangial and glomerular endothelial cells to 1 200 mg/L uric acid for 24 h caused a significant increase in the protein expressions of Kir6.1 and SUR2B(P＜0.05). Compared with the model group, the overexpressions of Kir6.1 and SUR2B were suppressed in presence of iptakalim at a concentration of 10 µmol/L (P＜0.05). These decreases in the expressions of Kir6.1 and SUR2B were prevented by the KATP channel blocker, no obvious difference in comparison with the model group (P＞0.05). Compare with the control group, monocytic adhesion to renal glomerular endothelial cells was notably promoted by 1 200 mg/L uric acid for 24 h (P＜0.01). Pretreatment with 10 µmol/L iptakalim for 24 h significantly reduced the monocytic adhesion in comparison with the model group (P＜0.05). It was showed that the inhibitory effects of iptakalim were antagonized by the KATP channel blocker, no obvious difference in comparison with the model group (P＞0.05). After stimulating glomerular endothelial cells with 1 200 mg/L uric acid for 24 hours, the secretion of MCP-1 was significantly increased compared to the control group (P＜0.05). Compare with the model group, preincubation with 10 µmol/L iptakalim significantly decreased MCP-1 production (P＜0.05). KATP channel blocker suppressed the downregulation of MCP-1 protein synthesis induced by iptakalim. After stimulation with uric acid, translocation of NF-κB from cytoplasms to nuclei of renal glomerular endothelial cells were observed, while that of NF-κB was suppressed in presence of iptakalim at the concentration of 10 µmol/L. This inhibition of NF-κB translocation was clearly prevented by KATP channel blocker. Conclusion: These results suggests that a new SUR2B/Kir6.1-type KATP channel opener iptakalim plays interventional roles in renal cells damages caused by uirc acid and its mechanism is involved in activating KATPchannels .

Iptakalim improves cerebral microcirculation in mice after ischemic stroke by inhibiting pericyte contraction.

Pericytes are present tight around the intervals of capillaries, play an essential role in stabilizing the blood-brain barrier, regulating blood flow and immunomodulation, and persistent contraction of pericytes eventually leads to impaired blood flow and poor clinical outcomes in ischemic stroke. We previously show that iptakalim, an ATP-sensitive potassium (K-ATP) channel opener, exerts protective effects in neurons, and glia against ischemia-induced injury. In this study we investigated the impacts of iptakalim on pericytes contraction in stroke. Mice were subjected to cerebral artery occlusion (MCAO), then administered iptakalim (10 mg/kg, ip). We showed that iptakalim administration significantly promoted recovery of cerebral blood flow after cerebral ischemia and reperfusion. Furthermore, we found that iptakalim significantly inhibited pericytes contraction, decreased the number of obstructed capillaries, and improved cerebral microcirculation. Using a collagen gel contraction assay, we demonstrated that cultured pericytes subjected to oxygen-glucose deprivation (OGD) consistently contracted from 3 h till 24 h during reoxygenation, whereas iptakalim treatment (10 µM) notably restrained pericyte contraction from 6 h during reoxygenation. We further showed that iptakalim treatment promoted K-ATP channel opening via suppressing SUR2/EPAC1 complex formation. Consequently, it reduced calcium influx and ET-1 release. Taken together, our results demonstrate that iptakalim, targeted K-ATP channels, can improve microvascular disturbance by inhibiting pericyte contraction after ischemic stroke. Our work reveals that iptakalim might be developed as a promising pericyte regulator for treatment of stroke.

Iptakalim alleviates synaptic damages via targeting mitochondrial ATP-sensitive potassium channel in depression.

Synaptic plasticity damages play a crucial role in the onset and development of depression, especially in the hippocampus, which is more susceptible to stress and the most frequently studied brain region in depression. And, mitochondria have a major function in executing the complex processes of neurotransmission and plasticity. We have previously demonstrated that Iptakalim (Ipt), a new ATP-sensitive potassium (K-ATP) channel opener, could improve the depressive-like behavior in mice. But the underlying mechanisms are not well understood. The present study demonstrated that Ipt reversed depressive-like phenotype in vivo (chronic mild stress-induced mice model of depression) and in vitro (corticosterone-induced cellular model). Further study showed that Ipt could upregulate the synaptic-related proteins postsynaptic density 95 (PSD 95) and synaptophysin (SYN), and alleviated the synaptic structure damage. Moreover, Ipt could reverse the abnormal mitochondrial fission and fusion, as well as the reduced mitochondrial ATP production and collapse of mitochondrial membrane potential in depressive models. Knocking down the mitochondrial ATP-sensitive potassium (Mito-KATP) channel subunit MitoK partly blocked the above effects of Ipt. Therefore, our results reveal that Ipt can alleviate the abnormal mitochondrial dynamics and function depending on MitoK, contributing to improve synaptic plasticity and exert antidepressive effects. These findings provide a candidate compound and a novel target for antidepressive therapy.

Evaluation of the Potential Effect of Iptakalim Hydrochloride on the QT Interval in Single- and Multiple-Ascending-Dose Studies Using Concentration-QTc Analysis.

Cardiotoxicity has been one of the most common causes of withdrawal of drugs from the market, and prolongation of the QT interval is one of the manifestations of drug cardiotoxicity. Iptakalim hydrochloride (ITKL) is a selective ATP-sensitive potassium channel opener used to treat hypertension. It is crucial to assess the risk of cardiac repolarization of ITKL in clinical trials. This study was conducted to determine the effect of ITKL on corrected QT (QTc) interval. A randomized, double-blind, placebo-controlled single- and multidose regimen was carried out to investigate the QTc and ITKL concentration correlation. ITKL was administered at doses of 5, 10, 15, and 20 mg with single oral administration and 10 and 20 mg with multiple oral administration, along with placebo, in 83 healthy subjects. Electrocardiograms (ECGs) and blood samples were collected on a preset time schedule. A ΔΔQTcF effect above 10 milliseconds was excluded at all observed plasma levels. Among them, the highest dose was 20 mg, which is twice the therapeutic dose. We concluded that ITKL did not prolong the QT interval in healthy subjects within the therapeutic dose. Retrospectively registered: The study was registered at Chinese Clinical Trial Registry with registration number ChiCTR1800014466.

Iptakalim ameliorates hypoxia-impaired human endothelial colony-forming cells proliferation, migration, and angiogenesis via Akt/eNOS pathways.

Hypoxia-associated pulmonary hypertension is characterized by pulmonary vascular remodeling. Pulmonary arterial endothelial cells dysfunction is considered as the initial event. As precursor of endothelial cells, endothelial colony-forming cells (ECFCs) play significant roles in maintenance of endothelium integrity and restoration of normal endothelial cell function. Accumulating data have indicated that hypoxia leads to a decrease in the number and function of ECFCs with defective capacity of endothelial regeneration. Previous studies have reported that the activation of ATP-sensitive potassium channels (KATP) shows therapeutic effects in pulmonary hypertension. However, there have been few reports focusing on the impact of KATP on ECFC function under hypoxic condition. Therefore, the aim of this study was to investigate whether the opening of KATP could regulate hypoxia-induced ECFC dysfunction. Using ECFCs derived from adult peripheral blood, we observed that Iptakalim (Ipt), a novel KATP opener (KCO), significantly promoted ECFC function including cellular viability, proliferation, migration, angiogenesis, and apoptosis compared with ECFCs exposed to hypoxia. Glibenclamide (Gli), a nonselective KATP blocker, could eliminate the effects. The protective role of Ipt is attributed to an increased production of nitric oxide (NO), as well as an enhanced activation of angiogenic transduction pathways, containing Akt and endothelial nitric oxide synthase. Our observations demonstrated that KATP activation could improve ECFC function in hypoxia via Akt/endothelial nitric oxide synthase pathways, which may constitute increase ECFC therapeutic potential for hypoxia-associated pulmonary hypertension treatment.

SUR2B/Kir6.1 channel openers correct endothelial dysfunction in chronic heart failure via the miR-1-3p/ET-1 pathway.

The SUR2B/Kir6.1 channel openers iptakalim and natakalim reverse cardiac remodeling and ameliorate endothelial dysfunction by re-establishing the balance between the nitric oxide and endothelin systems. In this study, we investigated the microRNAs (miRs) involved in the molecular mechanisms of SUR2B/Kir6.1 channel opening in chronic heart failure. Both iptakalim and natakalim significantly upregulated the expression of miR-1-3p, suggesting that this miR is closely associated with the therapeutic effects against chronic heart failure. Bioinformatic analysis showed that many of the 183 target genes of miR-1-3p are involved in cardiovascular diseases, suggesting that miR-1-3p plays a vital role in such diseases and vascular remodeling. Target gene prediction showed that miR-1-3p combines with the 3' untranslated region (UTR) of endothelin-1 (ET-1) mRNA. Iptakalim and natakalim upregulated miR-1-3p expression and downregulated ET-1 mRNA expression in vitro. The dual luciferase assay confirmed that there is a complementary binding sequence between miR-1-3p and the 3' UTR 158-165 sequence of ET-1 mRNA. To verify the effect of miR-1-3p on ET-1, lentiviral vectors overexpressing or inhibiting miR-1-3p were constructed for the transduction of rat primary cardiac microvascular endothelial cells. The results showed that natakalim enhanced the miR-1-3p level. miR-1-3p overexpression downregulated the expression of ET-1, whereas miR-1-3p inhibition had the opposite effect. Therefore, we verified that SUR2B/Kir6.1 channel openers could correct endothelial imbalance and ameliorate chronic heart failure through the miR-1-3p/ET-1 pathway in endothelial cells. Our study provides comprehensive insights into the molecular mechanisms behind the SUR2B/Kir6.1 channel's activity against chronic heart failure.

Activation of ATP-sensitive potassium channel by iptakalim normalizes stress-induced HPA axis disorder and depressive behaviour by alleviating inflammation and oxidative stress in mouse hypothalamus.

Stress-induced disturbance of the hypothalamic-pituitary-adrenal (HPA) axis is strongly implicated in incidence of mood disorders. A heightened neuroinflammatory response and oxidative stress play a fundamental role in the dysfunction of the HPA axis. We have previously demonstrated that iptakalim (Ipt), a new ATP-sensitive potassium (K-ATP) channel opener, could prevent oxidative injury and neuroinflammation against multiple stimuli-induced brain injury. The present study was to demonstrate the impacts of Ipt in stress-induced HPA axis disorder and depressive behavior. We employed 2 stress paradigms: 8 weeks of continuous restraint stress (chronic restraint stress, CRS) and 2h of restraint stress (acute restraint stress, ARS), to mimic both chronic stress and severe acute stress. Prolonged (4 weeks) and short-term (a single injection) Ipt treatment was administered 30min before each stress paradigm. We found that HPA axis was altered after stress, with different responses to CRS (lower ACTH and CORT, higher AVP, but normal CRH) and ARS (higher CRH, ACTH and CORT, but normal AVP). Both prolonged and short-term Ipt treatment normalized stress-induced HPA axis disorders and abnormal behaviors in mice. CRS and ARS up-regulated mRNA levels of inflammation-related molecules (TNFα, IL-1ß, IL-6 and TLR4) and oxidative stress molecules (gp91phox, iNOS and Nrf2) in the mouse hypothalamus. Double immunofluorescence showed CRS and ARS increased microglia activation (CD11b and TNFα) and oxidative stress in neurons (NeuN and gp91phox), which were alleviated by Ipt. Therefore, the present study reveals that Ipt could prevent against stress-induced HPA axis disorders and depressive behavior by alleviating inflammation and oxidative stress in the hypothalamus.

Activation of ATP-sensitive potassium channels facilitates the function of human endothelial colony-forming cells via Ca2+ /Akt/eNOS pathway.

Accumulating data, including those from our laboratory, have shown that the opening of ATP-sensitive potassium channels (KATP ) plays a protective role in pulmonary vascular diseases (PVD). As maintainers of the endothelial framework, endothelial colony-forming cells (ECFCs) are considered excellent candidates for vascular regeneration in cases of PVD. Although KATP openers (KCOs) have been demonstrated to have beneficial effects on endothelial cells, the impact of KATP on ECFC function remains unclear. Herein, this study investigated whether there is a distribution of KATP in ECFCs and what role KATP play in ECFC modulation. By human ECFCs isolated from adult peripheral blood, KATP were confirmed for the first time to express in ECFCs, comprised subunits of Kir (Kir6.1, Kir6.2) and SUR2b. KCOs such as the classical agent nicorandil (Nico) and the novel agent iptakalim (Ipt) notably improved the function of ECFCs, promoting cell proliferation, migration and angiogenesis, which were abolished by a non-selective KATP blocker glibenclamide (Gli). To determine the underlying mechanisms, we investigated the impacts of KCOs on CaMKII, Akt and endothelial nitric oxide synthase pathways. Enhanced levels were detected by western blotting, which were abrogated by Gli. This suggested an involvement of Ca2+ signalling in the regulation of ECFCs by KATP . Our findings demonstrated for the first time that there is a distribution of KATP in ECFCs and KATP play a vital role in ECFC function. The present work highlighted a novel profile of KATP as a potential target for ECFC modulation, which may hold the key to the treatment of PVD.

Iptakalim induces mitochondria-dependent apoptosis in hypoxic rat pulmonary arterial smooth muscle cells.

OBJECTIVES: Pulmonary vascular medial hypertrophy in hypoxic pulmonary arterial hypertension (HPH) is caused in part by decreased apoptosis in pulmonary artery smooth muscle cells (PASMCs). Iptakalim (Ipt), an ATP sensitive potassium channel opener, ameliorates HPH in animal models. Here we investigated the effects of Ipt on proliferation and apoptosis of hypoxic rat PASMCs, and to determine the possible underlying mechanisms. METHODS: Primary rat PASMCs were isolated and cultured. PASMCs were cultured for 24h in normoxia or hypoxia (5% O2) conditions with and without Ipt. Cell proliferation and cycle were determined by MTT assay and flow cytometry, respectively. Mitochondrial membrane potential (Δym) was detected by fluorescence microscope Western blot assays were used to examine the expression of cyclin D, CDK4, endothelin-1 (ET-1), hypoxia-inducible factor-1 (HIF-1), platelet-derived growth factor-BB (PDGF-BB), Bax, Bcl-2, cytochrome c (Cyt c), caspase-9, and caspase-3 in PASMCs. RESULTS: We found that hypoxia significantly stimulated proliferation and rendered resistance to apoptosis in PASMCs. Ipt suppressed proliferation and induced cell cycle arrest in hypoxia PASMCs. Ipt decreased the expression of cyclin D, CDK4, HIF-1, ET-1, and PDGF-BB in hypoxia PASMCs. It reversed the depolarization of Δψm in hypoxia PASMCs too. Ipt significantly upregulated Bax expression and downregulated Bcl-2 expression, and promoted the release of Cyt c from mitochondria to cytoplasm in hypoxia PASMCs. Furthermore, Ipt significantly activated the caspase cascades evidenced by increased expression of caspase-9 and caspase-3 in hypoxia PASMCs. CONCLUSIONS: Ipt could inhibit cell proliferation and induce apoptosis associated with cell cycle arrest, decreased ET-1, HIF-1, cyclin D, CDK4, PDGF-BB and Δψm, increased Bax/Bcl-2 ratio, enhanced Cyt c release, and activation of caspases in PASMCs under hypoxia status. Our data indicated that Ipt could be a therapeutic candidate for treatment of HPH.

ATP-sensitive potassium channels: uncovering novel targets for treating depression.

ATP-sensitive potassium (K-ATP) channels have been shown to couple membrane electrical activity to energy metabolism in a variety of cells and are important in several physiological systems. In the brain, K-ATP channels are strongly expressed in the neuronal circuitry. The distributional profile and functional significance of K-ATP channels suggest that they may be involved in stress-induced depression. First, we showed that chronic mild stress (CMS) significantly increased the expression of hippocampal Kir6.2 and Kir6.1 subunits of K-ATP channels. Next, using Kir6.2 knockout (Kir6.2(-/-)) mice, we presented that Kir6.2 deficiency resulted in antidepressant-like behaviors under non-stress conditions, but aggravated depressive behaviors accompanied by the loss of CA3 neuron and the reduction of brain-derived neurotrophic factor in hippocampus under chronic stress. Finally, we demonstrated that the K-ATP channel opener iptakalim, as well as a classical antidepressant fluoxetine, can reverse CMS-induced depression-related behaviors and counteract the deleterious effects of stress on hippocampus in wild-type mice, but only partially alleviate these symptoms in Kir6.2(-/-) mice. Collectively, our findings demonstrate that K-ATP channels are involved in the pathogenesis of depression and may be a promising target for the therapy of depression.

[Iptakalim ameliorates relaxation to acetylcholine in thoracic aortic rings impaired by microvesicles derived from hypoxia/reoxygenation-treated HUVECs].

OBJECTIVE: To investigate the effect of Iptakalim (Ipt) preventing injury of endothelial microvesicles (EMVs) derived from hypoxia/reoxygenation (H/R)-treated HUVECs on the relaxation of rat thoracic aortic rings and explore the underlying mechanism. METHODS: H/R injury model was established to release H/R-EMVs from HUVECs. H/R-EMVs from HUVECs were isolated by ultracentrifugation from the conditioned culture medium. H/R-EMVs were characterized by using Transmission Electron Microscope (TEM). Thoracic aortic rings of rats were incubated with 10-7-10-3 mol/L Ipt and co-cultured with 10 µg/ml H/R-EMVs for 4 hours, and their endothelium-dependent relaxation in response to acetylcholine (ACh) was recorded in vitro. The nitric oxide (NO) production of ACh-treated rat thoracic aortic rings was measured by using Griess reagent. The expression of endothelial NO synthase (eNOS), phosphorylated eNOS (p-eNOS, Ser-1177), serine/threonine kinas (Akt) and phosphorylated Akt (p-Akt, Ser-473) in the thoracic aortic rings of rats was detected by Western blotting. RESULTS: H/R-EMVs were induced by H/R-treated HUVECs and isolated by ultracentrifugation. The isolated H/R-EMVs subjected to TEM revealed small, rounded vesicles (100-1 000 nm) surrounded by a membrane. H/R-EMVs impaired relaxation induced by ACh of rat thoracic aortic rings significantly. Compared with H/R-EMVs treatment individually, relaxation and NO production of rat thoracic aortic rings were increased by Ipt treatment in a concentration-dependent manner (P<0.05, P<0.01). The expression of total eNOS (t-eNOS) and total Akt (t-Akt) was not affected by Ipt or H/R-EMVs. However, the expression of p-eNOS and p-Akt increased after treated with Ipt (P<0.01). CONCLUSIONS: Based on H/R-EMVs treatment, ACh induced endothelium-dependent relaxation of rat thoracic aortic rings was ameliorated by Ipt in a concentration-dependent manner. The mechanisms involved the increase in NO production, p-eNOS and p-Akt expression.

[Molecular of pulmonary arterioles relaxation through SUR2B/Kir6.1 channel opening].

OBJECTIVE: To study the dilatation characteristics of ATP-sensitive potassium channel (KATP) SUR2B/Kir6.1 subtype opener iptakalim (Ipt) in pulmonary arterioles, and to explore its possible mechanism. METHODS: Vessels pressure-diameter monitoring perfusion technique was used to observe the dilatation effects of Ipt in rats fourth pulmonary arterioles (n=6~8). After the pulmonary arterioles were pre-treated with removing endothelium or pre-incubated with KATP channel blocker glibenclamide (Gli), cyclo-oxygenase (COX) inhibitor indomethacin (Indo) and nitric oxide synthase (NOS) inhibitor L-Nω-Nitro-arginine methyl ester(L-NAME), the dilatation effects of Ipt were observed. RESULTS: Pulmonary arterioles could be relaxed by Ipt, the maximal relaxation rate was (60.53±2.08)%. Compaired with control group, the effects of Ipt in endothelium denuded arterioles were significantly decreased, the maximal relaxation rate was (9.47±1.56)% (P<0.01). The maximal relaxation rate were decreased to(17.49±1.47)%,(37.00±3.88)% and(24.91±2.30)% respectively after Gli,Indo,L-NAME were pre-incubated (P<0.01). CONCLUSIONS: Pulmonary arterioles can be relaxed by Ipt. The selective activation of KATP SUR2B/Kir6.1 subtype by Ipt was involved in its mechanisms. The endothelium-dependently dilatation of Ipt was related to nitric oxide (NO) and prostacyclin (PGI2) released by endothelial cells.

Iptakalim inhibits PDGF-BB-induced human airway smooth muscle cells proliferation and migration.

Chronic airway diseases are characterized by airway remodeling which is attributed partly to the proliferation and migration of airway smooth muscle cells (ASMCs). ATP-sensitive potassium (KATP) channels have been identified in ASMCs. Mount evidence has suggested that KATP channel openers can reduce airway hyperresponsiveness and alleviate airway remodeling. Opening K(+) channels triggers K(+) efflux, which leading to membrane hyperpolarization, preventing Ca(2+)entry through closing voltage-operated Ca(2+) channels. Intracellular Ca(2+) is the most important regulator of muscle contraction, cell proliferation and migration. K(+) efflux decreases Ca(2+) influx, which consequently influences ASMCs proliferation and migration. As a KATP channel opener, iptakalim (Ipt) has been reported to restrain the proliferation of pulmonary arterial smooth muscle cells (PASMCs) involved in vascular remodeling, while little is known about its impact on ASMCs. The present study was designed to investigate the effects of Ipt on human ASMCs and the mechanisms underlying. Results obtained from cell counting kit-8 (CCK-8), flow cytometry and 5-ethynyl-2'-deoxyuridine (EdU) incorporation showed that Ipt significantly inhibited platelet-derived growth factor (PDGF)-BB-induced ASMCs proliferation. ASMCs migration induced by PDGF-BB was also suppressed by Ipt in transwell migration and scratch assay. Besides, the phosphorylation of Ca(2+)/calmodulin-dependent kinase II (CaMKII), extracellular regulated protein kinases 1/2 (ERK1/2), protein kinase B (Akt), and cyclic adenosine monophosphate (cAMP) response element binding protein (CREB) were as well alleviated by Ipt administration. Furthermore, we found that the inhibition of Ipt on the PDGF-BB-induced proliferation and migration in human ASMCs was blocked by glibenclamide (Gli), a selective KATP channel antagonist. These findings provide a strong evidence to support that Ipt antagonize the proliferating and migrating effects of PDGF-BB on human ASMCs through opening KATP channels. Altogether, our results highlighted a novel profile of Ipt as a potent option against the airway remodeling in chronic airway diseases.

Iptakalim protects against ischemic injury by improving neurovascular unit function in the mouse brain.

It has been reported that the novel ATP-sensitive potassium (K-ATP) channel opener iptakalim (IPT) decreases ischemic neuronal damage in rats. However, the mechanisms underlying neuroprotection are still to be fully elucidated. The results of this study showed that mice with ischemia induced by middle cerebral artery occlusion exhibited higher mortality and more neurological deficits, as well as larger infarct volume, compared with sham mice. Moreover, it was found that ischemia activated astrocytes surrounding CA1 neurons with an increased expression of D-serine, induced greater microglial activation accompanied by higher tumor necrosis factor alpha (TNF-α) production, and caused higher expressions of matrix metalloproteinase 9 (MMP-9) in the endothelial cells of mice. Pretreatment with IPT significantly attenuated the neurological deficits and decreased the infarct volume in mice. IPT treatment could decrease MMP-9 secretion, inhibit astrocytic activation with decreasing D-serine and elevating connexin43 expression. Microglial activation was also inhibited and TNF-α production was decreased by IPT. Taken together, a K-ATP channel opener may improve the function of neurovascular unit and protect against ischemic injury. These findings suggest that targeting K-ATP channels provides a promising therapeutic approach for stroke.

Iptakalim attenuates self-administration and acquired goal-tracking behavior controlled by nicotine.

Iptakalim is an ATP-sensitive potassium channel opener, as well as an α4ß2-containing nicotinic acetylcholine receptor (nAChR) antagonist. Pretreatment with iptakalim diminishes nicotine-induced dopamine (DA) and glutamate release in the nucleus accumbens. This neuropharmacological profile suggests that iptakalim may be useful for treatment of nicotine dependence. Thus, we examined the effects of iptakalim in two preclinical models. First, the impact of iptakalim on the interoceptive stimulus effect of nicotine was evaluated by training rats in a discriminated goal-tracking task that included intermixed nicotine (0.4 mg/kg, SC) and saline sessions. Sucrose was intermittently presented in a response-independent manner only on nicotine sessions. On intervening test days, rats were pretreated with iptakalim (10, 30, 60 mg/kg, IP). Results revealed that iptakalim attenuated nicotine-evoked responding controlled by the nicotine stimulus in a dose-dependent manner. In a separate study, the impact of iptakalim on the reinforcing effects of nicotine was investigated by training rats to lever-press to self-administer nicotine (0.01 mg/kg/infusion) [Dosage error corrected]. Results revealed that pretreatment with iptakalim (1, 3, 6 mg/kg, IV) decreased nicotine intake (i.e., less active lever responding). Neither behavioral effect was due to a non-specific motor effect of iptakalim, nor to an ability of iptakalim to inhibit DA transporter (DAT) or serotonin transporter (SERT) function. Together, these finding support the notion that iptakalim may be an effective pharmacotherapy for increasing smoking cessation and a better understanding of its action could contribute to medication development.

Iptakalim Preferentially Decreases Nicotine-induced Hyperlocomotion in Phencyclidine-sensitized Rats: A Potential Dual Action against Nicotine Addiction and Psychosis.

OBJECTIVE: Iptakalim is a putative ATP-sensitive potassium (K(ATP)) channel opener. It is also a novel nicotinic acetylcholine receptor (nAChR) blocker and can antagonize nicotine-induced increase in dopamine release in the nucleus accumbens. Our recent work also shows that iptakalim exhibits a clozapine-like atypical antipsychotic profile, indicating that iptakalim may possess a dual action against nicotine addiction and schizophrenia. METHODS: The present study examined the potential therapeutic effects of iptakalim on nicotine use in schizophrenia. We created an animal model of comorbidity of nicotine addiction and schizophrenia by injecting male Sprague-Dawley rats with nicotine (0.40 mg/kg, subcutaneously[sc]) or saline, in combination with phencyclidine (PCP, 3.0 mg/kg, sc) or saline daily for 14 consecutive days. RESULTS: During the PCP/nicotine sensitization phase, PCP and nicotine independently increased motor activity over time. PCP also disrupted prepulse inhibition (PPI) of acoustic startle response. Acute nicotine treatment attenuated the PCP-induced hyperlocomotion and PCP-induced disruption of PPI, whereas repeated nicotine treatment potentiated these effects. Importantly, pretreatment with iptakalim (10-20 mg/kg, intraperitoneally) reduced nicotine-induced hyperlocomotion in a dose-dependent fashion. This reduction effect was highly selective: it was more effective in rats previously sensitized to the combination of PCP and nicotine, but less effective in rats sensitized to saline, nicotine alone or PCP alone. CONCLUSION: To the extent that the combined nicotine and PCP sensitization mimics comorbid nicotine addiction in schizophrenia, the preferential inhibitory effect of iptakalim on nicotine-induced hyperlocomotion suggests that iptakalim may be a potential useful drug for the treatment nicotine abuse in schizophrenia.

Iptakalim Preferentially Decreases Nicotine-induced Hyperlocomotion in Phencyclidine-sensitized Rats: A Potential Dual Action against Nicotine Addiction and Psychosis

OBJECTIVE: Iptakalim is a putative ATP-sensitive potassium (KATP) channel opener. It is also a novel nicotinic acetylcholine receptor (nAChR) blocker and can antagonize nicotine-induced increase in dopamine release in the nucleus accumbens. Our recent work also shows that iptakalim exhibits a clozapine-like atypical antipsychotic profile, indicating that iptakalim may possess a dual action against nicotine addiction and schizophrenia. METHODS: The present study examined the potential therapeutic effects of iptakalim on nicotine use in schizophrenia. We created an animal model of comorbidity of nicotine addiction and schizophrenia by injecting male Sprague-Dawley rats with nicotine (0.40 mg/kg, subcutaneously[sc]) or saline, in combination with phencyclidine (PCP, 3.0 mg/kg, sc) or saline daily for 14 consecutive days. RESULTS: During the PCP/nicotine sensitization phase, PCP and nicotine independently increased motor activity over time. PCP also disrupted prepulse inhibition (PPI) of acoustic startle response. Acute nicotine treatment attenuated the PCP-induced hyperlocomotion and PCP-induced disruption of PPI, whereas repeated nicotine treatment potentiated these effects. Importantly, pretreatment with iptakalim (10-20 mg/kg, intraperitoneally) reduced nicotine-induced hyperlocomotion in a dose-dependent fashion. This reduction effect was highly selective: it was more effective in rats previously sensitized to the combination of PCP and nicotine, but less effective in rats sensitized to saline, nicotine alone or PCP alone. CONCLUSION: To the extent that the combined nicotine and PCP sensitization mimics comorbid nicotine addiction in schizophrenia, the preferential inhibitory effect of iptakalim on nicotine-induced hyperlocomotion suggests that iptakalim may be a potential useful drug for the treatment nicotine abuse in schizophrenia.

Iptakalim, a novel ATP-sensitive potassium channel opener, inhibits pulmonary arterial smooth muscle cell proliferation by downregulation of PKC-α.

Iptakalim is a new ATP-sensitive potassium (KATP) channel opener, and it inhibits the proliferation of pulmonary arterial smooth muscle cells (PASMCs) and pulmonary vascular remodeling. However, the underlying mechanism remains unclear. In the present study, we found that iptakalim significantly decreased pulmonary artery pressure, inhibited pulmonary ariery remodeling and PKC-α overexpression in chronic hypoxia in a rat pulmonary hypertension model. Iptakalim reduced hypoxia-induced expression of PKC-α, and abolished the effect of hypoxia on PASMC proliferation significantly in a dose-dependent manner in vitro. Moreover, these effects were abolished by glibenclamide, a selective KATP channel antagonist. These results indicate that iptakalim inhibits PASMC proliferation and pulmonary vascular remodeling induced by hypoxia through downregulating the expression of PKC-α. Iptakalim can serve as a novel promising treatment for hypoxic pulmonary hypertension.

Effects of iptakalim on renal injury induced by lipopolysaccharide, oleic acid and diethylene glycol / 国际药学研究杂志

Objective: To observe the effects of iptakalim on renal injury induced by lipopolysaccharide (LPS), oleic acid and diethylene glycol(DEG). Methods: By njection of 2% ead acetate and 1 μg (1 ml/kg) LPS to rats' femoral vein, 4 h later the experimental models of renal injury induced by LPS have been developed. By injection of 0.15 ml/kg oleic acid to rats' left renal artery, 24h later the experimental models of renal injury induced by oleic acid have been developed. Iptakalim was orally gavaged at the doses of 1,3,9 mg/(kg · d) for 3 d and 1 h before injury. The experimental models of renal injury have been developed by injection of DEG 10 g/kg to mice's peritoneal cavity, then iptakalim was orally gavaged at the doses of 1,3,9 mg/(kg·d) for 6 d. After the experimental models have been set up, observe the serum levels of creatinine(Cr), blood urea nitrogen(BUN) and pathological changes in renal tissue, for the further evaluation of renal function. Results: (1) In rats with the shock induced by LPS, significantly increased serum evels of Cr and BUN were found. Renal cortex of injury rats showed obviously glomerulus microthrombi, tubular cell swelling, necrosis, congestion and cast. Pretreatment of iptakalim at the dose of 9 mg/kg showed improved renal dysfunction and pathological changes in renal tissue. (2) In rats with the renal injury induced by oleic acid, significantly increased serum levels of Cr and BUN were found. Renal cortex of renal injury rats showed obviously glomerulus endothelial cell necrosis, tubular cell congestion and cell cast. Iptakalim had no effect on damaged renal function and the morphological changes in renal tissue. (3) In mice with the renal injury induced by 10 g/kg of DEG, significantly increased serum evels of Cr were found. Iptakalim at the doses of 9 mg/kg decreased serum evels of Cr to normal level. Conclusion: Iptakalim does not fit for individuals of renal damage caused by LPS or oleic acid. The protective effects of iptakalim against renal damaged by DEG need to be further investigated.

Effects of iptakalim on the functions of endothelin system in human pulmonary artery endothelial cells / 中国药理学通报

Aim To investigate the effects of iptakalim(IPT),a novel K_(ATP) opener,on the functions of endothelin system in human pulmonary artery endothelial cells.Methods Primary cultured human pulmonary artery endothelial cells were incubated with different concentrations iptakalim for 24 h.The levels of ET-1 in medium were observed by radioimmunoassay.Reverse transcription polymerase chain reaction(RT-PCR)was performed to analyze the expression of ET-1 and ECE.Results When endothelial cells were incubated with IPT at concentrations above 10 μmol·L~(-1),the levels of ET-1 release in medium and the levels of ET-1 mRNA were significantly inhibited.When endothelial cells were incubated with IPT at concentrations above 1 μmol·L~(-1),the levels of ECE mRNA were significantly inhibited.Conclusions IPT can inhibit the expression of ET-1 and ECE mRNA from human pulmonary artery endothelial cells, thus it inhibits the secretion of ET-1 from endothelial cells. Iptakalim may serve as a promising candidate drug to treat pulmonary hypertension.