NS309 |
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Catalog No.GC12528
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NS309 is the most potent positive gating modulator for intermediate-conductance Ca2+-activated K+ channel KCa3.1, with an EC50 of 75nmol/L.
Products are for research use only. Not for human use. We do not sell to patients.
Cas No.: 18711-16-5
Sample solution is provided at 25 µL, 10mM.
NS309 is the most potent positive gating modulator for intermediate-conductance Ca2+-activated K+ channel KCa3.1, with an EC50 of 75nmol/L[1]. NS309 was binding within the interface between calmodulin's N-lobe and the S4-S5 linker to exhibit the agonist activity, and NS309 forms hydrogen bonds between the NS309’s carbonyl and residues N201 and R287[2]. NS309 functions as a pharmacological agent to enhance the activity of both small and intermediate conductance calcium-activated potassium channels[3].
In vitro, NS309 can stimulate changes in the cell's ions[4]. The exposure of diabetes-derived human coronary endothelial cells to 10μmol/L NS309 for 15 minutes led to a significant rise in total K+ current while simultaneously causing cell hyperpolarization[4]. Human red cells displayed near full dehydration after 2 hours when treated with NS309 at 100μmol/L in a medium containing only 4μmol/L external Ca2+[5]. The administration of NS309 (10μmol/L for 2 minutes) led to a significant rise in whole cell small conductance Ca2+-activated K+ currents while causing hyperpolarization of the resting membrane potential in detrusor smooth muscle cell of rats[6].
In vivo, NS309 has neuroprotective effects[7]. Intraperitoneal injection of 2mg/kg NS309 for 10 days significantly reduced brain edema and neuronal apoptosis in rats with traumatic brain injury, and decreased the number of neutrophils, lymphocytes and microglia[7]. The administration of NS309 through the intrathecal route at concentrations of 100μmol/L for 30 minutes reduced complete Freund adjuvant (CFA)-induced mechanical hypersensitivity in the rat model of inflammatory pain[8].
References:
[1]Nasburg J, Wulff H, Shim H, et al. Exploring the binding site and mechanism of action of NS309, a superagonistic positive gating modulator for the calcium-activated potassium channel KCa3. 1[J]. Biophysical Journal, 2024, 123(3): 261a-262a.
[2]Nasburg J A. Mapping the binding site of NS309, a superagonistic positive gating modulator for the calcium-activated potassium channel KCa3. 1[J]. Biophysical Journal, 2023, 122(3): 252a.
[3]Nasburg J A, Rouen K C, Dietrich C J, et al. NS309 Functions as a Superagonist for the Calcium-Activated Potassium Channel KCa3. 1[J]. Molecular Pharmacology, 2025: 100018.
[4]Liu Y, Xie A, Singh A K, et al. Inactivation of endothelial small/intermediate conductance of calcium‐activated potassium channels contributes to coronary arteriolar dysfunction in diabetic patients[J]. Journal of the american heart association, 2015, 4(8): e002062.
[5]Seear R V, Lew V L. IKCa agonist (NS309)-elicited all-or-none dehydration response of human red blood cells is cell-age dependent[J]. Cell Calcium, 2011, 50(5): 444-448.
[6]Parajuli S P, Hristov K L, Soder R P, et al. NS309 decreases rat detrusor smooth muscle membrane potential and phasic contractions by activating SK3 channels[J]. British journal of pharmacology, 2013, 168(7): 1611-1625.
[7]Chen T, Zhu J, Hang C H, et al. The potassium SK channel activator NS309 protects against experimental traumatic brain injury through anti-inflammatory and immunomodulatory mechanisms[J]. Frontiers in pharmacology, 2019, 10: 1432.
[8]Hipólito L, Fakira A K, Cabañero D, et al. In vivo activation of the SK channel in the spinal cord reduces the NMDA receptor antagonist dose needed to produce antinociception in an inflammatory pain model[J]. Pain, 2015, 156(5): 849-858.
| Cell experiment [1]: | |
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Cell lines |
Human coronary artery endothelial cells |
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Preparation Method |
The human coronary artery endothelial cells (HCAECs) at passage four received two washes of Ca2+-free Dulbecco's Modified Eagle Medium (DMEM) before undergoing incubation with 0.05% trypsin and 0.02% EDTA for 1 to 2 minutes. Use a perforated whole-cell voltage-clamp method with an Axopatch-200B amplifier to record K+ currents. The bath solution contained 140mmol/L NaCl and 5mmol/L KCl along with 1mmol/L CaCl2 and 2mmol/L MgCl2 while 10mmol/L HEPES and 30mmol/L glucose were added to achieve pH 7.4 at a temperature of 22°C. The resistance measurement for the patch pipette ranged from 2 to 5 megaohms. The pipette solution contained 110mmol/L aspartate, 20mmol/L KCl, 1mmol/L MgCl2, 9mmol/L CaCl2, 10mmol/L HEPES, 8mmol/L NaCl, 0.01mmol/L niflumic acid, and 10mmol/L BAPTA with a pH of 7.2 and free Ca2+ concentration of 1μmol/L. Cells received depolarization pulses every 5 seconds from −50mV holding potential reaching test potentials from −100 to +100mV in steps of +20mV for an overall 150mV duration. After treating cells with NS309 at 10μmol/L concentration tracings were collected across a potential range from −100 to +100mV while maintaining a holding potential of −50mV. The effect of the selective NS309 (10μmol/L) on the whole cell K+currents was examined. Both TRAM34 and apamin were also applied for testing the specificity of NS309. |
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Reaction Conditions |
10μmol/L; every 5 seconds |
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Applications |
NS309 treatment increased the total K+ currents of culture human coronary artery endothelial cells and induced the cell hyperpolarization. |
| Animal experiment [2]: | |
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Animal models |
Male Sprague-Dawley (SD) rats |
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Preparation Method |
Male Sprague-Dawley (SD) rats (3 months old, 250-280g body weight) were randomly divided into three groups (n = 6 each group): the NS309 pretreated group received an intraperitoneal injection of NS309 at 2mg/kg concentration (100µl per 20g body weight) 30 minutes before the traumatic brain injury (TBI). The sham group rats went through surgical procedures without any traumatic injury while the remaining rats received traumatic injury treatments. A saline solution containing 0.9% NaCl mixed with 1% DMSO served as the vehicle. At 24 hours post-TBI the rats were sacrificed to measure brain water content and perform TUNEL staining as well as apoptosis factor measurement and immunohistochemistry, while at 14 and 28 days they were sacrificed to measure contusion volume and at 12, 24, and 72 hours they were used for inflammatory cytokine measurement and TSG-6 and NF-κB p65 expression analysis. |
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Dosage form |
2mg/kg; i.p. |
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Applications |
NS309 treatment significantly reduced brain edema and neurological deficits caused by TBI, decreased neuronal apoptosis and significantly reduced the levels of proinflammatory cytokines (IL-1β, IL-6, and TNF-α) and chemokines (MCP-1, MIP-2, and RANTES). |
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References: |
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| Cas No. | 18711-16-5 | SDF | |
| Chemical Name | 6,7-dichloro-3-(hydroxyamino)-2H-indol-2-one | ||
| Canonical SMILES | O=C1N=C2C(Cl)=C(Cl)C=CC2=C1NO | ||
| Formula | C8H4Cl2N2O2 | M.Wt | 231.04 |
| Solubility | DMSO : 100 mg/mL (432.83 mM; Need ultrasonic) | Storage | Store at -20°C |
| General tips | Please select the appropriate solvent to prepare the stock solution according to the
solubility of the product in different solvents; once the solution is prepared, please store it in
separate packages to avoid product failure caused by repeated freezing and thawing.Storage method
and period of the stock solution: When stored at -80°C, please use it within 6 months; when stored
at -20°C, please use it within 1 month. To increase solubility, heat the tube to 37°C and then oscillate in an ultrasonic bath for some time. |
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| Shipping Condition | Evaluation sample solution: shipped with blue ice. All other sizes available: with RT, or with Blue Ice upon request. | ||
| Prepare stock solution | |||
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1 mg | 5 mg | 10 mg |
| 1 mM | 4.3283 mL | 21.6413 mL | 43.2825 mL |
| 5 mM | 865.7 μL | 4.3283 mL | 8.6565 mL |
| 10 mM | 432.8 μL | 2.1641 mL | 4.3283 mL |
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Quality Control & SDS
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- Purity: >98.00% Appearance: A solid
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Average Rating: 5 (Based on Reviews and 30 reference(s) in Google Scholar.)















