Ablation of small conductance calcium-activated potassium type-2 channel (SK2) delays occurrence of bupivacaine-induced cardiotoxicity in isolated mouse hearts

2020 ◽  
pp. 096032712095810
Author(s):  
H Chen ◽  
F Xia ◽  
X Chen ◽  
Y Cai ◽  
Z Jin
Keyword(s):  
Rate Pressure Product ◽  
Hek 293 ◽  
Hek 293 Cells ◽  
Severe Arrhythmia ◽  
293 Cells ◽  
Dependent Inhibition ◽  
Dose Dependent Inhibition ◽  
Dose Dependent ◽  
Small Conductance

Bupivacaine is frequently used for conducting regional anesthesia. When accidentally injected or excessively absorbed into circulation, bupivacaine can induce severe arrhythmia and potentially lead to cardiac arrest. The specific mechanisms underlying this cardiotoxicity, however, remain to be clarified. We transfected HEK-293 cells to express the small conductance calcium-activated potassium type-2 channel (SK2), and used a whole-cell patch clamp method in order to explore how bupivacaine affected these channels. We subsequently used SK2 knockout mice to explore the relevance of SK2 channels in bupivacaine-induced cardiotoxicity in isolating mouse hearts, mounting them on a Langendorff apparatus, and perfusing them with bupivacaine. Using this system, arrhythmia, asystole, and cardiac functions were monitored. We observed dose-dependent inhibition of SK2 channels by bupivacaine: half-maximal inhibitory concentration (IC50) value = 18.6 μM (95% CI 10.8–32.1). When SK2 knockout (SK2 −/−) or wild-type (WT) mice were perfused with Krebs-Henseleit buffer (KHB), we did not observe any instances of arrhythmia. When SK2 −/− mice or WT were perfused with KHB containing bupivacaine (40 μM), the time to arrhythmia (Tarrhythmia) and time to asystole (Tasystole) were both significantly longer in SK2 −/− mice relative to WT mice ( P < 0.001). Similarly, SK2 −/− mice exhibited a significantly longer time to 25%, 50%, and 75% reductions in heart rate (HR) and rate-pressure product (RPP) relative to WT mice following bupivacaine perfusion ( P < 0.001). These results reveal that bupivacaine was able to mediate a dose-dependent inhibition of SK2 channels in HEK-293 cells, and deletion of SK2 channels can delay bupivacaine-induced cardiotoxicity in isolated mouse hearts.

scholarly journals Bupivacaine inhibits a small conductance calcium-activated potassium type 2 channel (SK2) in HEK 293 cells

2019 ◽  
Author(s):  
Hongfei Chen ◽  
Fangfang Xia ◽  
Zhousheng Jin ◽  
Yuting He ◽  
Zhengjie Chen ◽  
...  
Keyword(s):  
Inhibitory Effect ◽  
Heart Cells ◽  
Dependent Manner ◽  
Patch Clamp Technique ◽  
Hek 293 ◽  
Hek 293 Cells ◽  
293 Cells ◽  
Ic50 Value ◽  
Small Conductance

Abstract Background: Bupivacaine blocks many ion channels in the heart muscle, which could cause severe cardiotoxicity. Small conductance calcium-activated potassium type 2 channels (SK2 channels) are widely distributed in the heart cells and are involved in relevant physiological functions. However, whether bupivacaine can inhibit SK2 channels is still unknown. This study investigated the effect of bupivacaine on SK2 channels. Methods: The SK2 channel gene was transfected into human embryonic kidney 293 cells (HEK-293 cells) with Lipofectamine 2000. The whole-cell patch clamp technique was used to study the effect of bupivacaine on SK2 channels. The inhibitory effect of various concentrations of bupivacaine on SK2 currents exhibited a non-linear relation, and the half-maximal inhibitory concentration (IC50) value was determined. Results: Bupivacaine inhibited the SK2 channels reversibly in a dose-dependent manner. The IC50 value of bupivacaine, ropivacaine and lidocaine on the SK2 current was 133.7, 189.3, and 885.8 µM, respectively. The degree of SK2 current inhibition by bupivacaine was dependent on the intracellular concentration of free calcium. Conclusions: The results of this study suggested a new inhibitory effect of bupivacaine on SK2 channels. Future studies should be concerned with the effects of SK2 on bupivacaine cardiotoxicity. Keywords: Bupivacaine, SK2 channel, inhibition, cardiotoxicity, HEK 293.

scholarly journals Bupivacaine inhibits a small conductance calcium‐activated potassium type 2 channel in human embryonic kidney 293 cells

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Hongfei Chen ◽  
Zhousheng Jin ◽  
Fangfang Xia ◽  
Zhijian Fu
Keyword(s):  
Free Calcium ◽  
Heart Cells ◽  
Dependent Manner ◽  
Human Embryonic Kidney ◽  
Patch Clamp Technique ◽  
Hek 293 ◽  
293 Cells ◽  
Ic50 Value ◽  
Small Conductance

Abstract Background Bupivacaine blocks many ion channels in the heart muscle, causing severe cardiotoxicity. Small-conductance calcium-activated potassium type 2 channels (SK2 channels) are widely distributed in the heart cells and are involved in relevant physiological functions. However, whether bupivacaine can inhibit SK2 channels is still unclear. This study investigated the effect of bupivacaine on SK2 channels. Methods The SK2 channel gene was transfected into human embryonic kidney 293 cells (HEK-293 cells) with Lipofectamine 2000. The whole-cell patch-clamp technique was used to examine the effect of bupivacaine on SK2 channels. The concentration–response relationship of bupivacaine for inhibiting SK2 currents (0 mV) was fitted to a Hill equation, and the half-maximal inhibitory concentration (IC50) value was determined. Results Bupivacaine inhibited the SK2 channels reversibly in a dose-dependent manner. The IC50 value of bupivacaine, ropivacaine, and lidocaine on SK2 currents was 16.5, 46.5, and 77.8µM, respectively. The degree of SK2 current inhibition by bupivacaine depended on the intracellular concentration of free calcium. Conclusions The results of this study suggested the inhibitory effect of bupivacaine on SK2 channels. Future studies should explore the effects of SK2 on bupivacaine cardiotoxicity.

scholarly journals Bupivacaine inhibits a small-conductance calcium-activated potassium type 2 channel (SK2) in HEK293 cells

2020 ◽  
Author(s):  
Hongfei Chen ◽  
Fangfang Xia ◽  
Zhousheng Jin ◽  
Zhijian Fu
Keyword(s):  
Hek293 Cells ◽  
Free Calcium ◽  
Heart Cells ◽  
Dependent Manner ◽  
Patch Clamp Technique ◽  
Hek 293 ◽  
293 Cells ◽  
Ic50 Value ◽  
Small Conductance

Abstract Background: Bupivacaine blocks many ion channels in the heart muscle, which could cause severe cardiotoxicity. Small conductance calcium-activated potassium type 2 channels (SK2 channels) are widely distributed in the heart cells and are involved in relevant physiological functions. However, whether bupivacaine can inhibit SK2 channels is still unknown. This study investigated the effect of bupivacaine on SK2 channels.Methods: The SK2 channel gene was transfected into human embryonic kidney 293 cells (HEK-293 cells) with Lipofectamine 2000. The whole-cell patch clamp technique was used to study the effect of bupivacaine on SK2 channels. Concentration-response relationship of bupivacaine for inhibiting SK2 current (0 mV) was fitted to a Hill equation, and the half-maximal inhibitory concentration (IC50) value was determined.Results: Bupivacaine inhibited the SK2 channels reversibly in a dose-dependent manner. The IC50 value of bupivacaine, ropivacaine and lidocaine on the SK2 current was 16.5, 46.5, and 77.8 µM, respectively. The degree of SK2 current inhibition by bupivacaine was dependent on the intracellular concentration of free calcium.Conclusions: The results of this study suggested a new inhibitory effect of bupivacaine on SK2 channels. Future studies should be concerned with the effects of SK2 on bupivacaine cardiotoxicity.

Type 2 IP3 receptors are involved in uranyl acetate induced apoptosis in HEK 293 cells

Toxicology ◽  
2009 ◽  
Vol 262 (1) ◽  
pp. 73-79 ◽  
Author(s):  
Juraj Kopacek ◽  
Karol Ondrias ◽  
Barbora Sedlakova ◽  
Jana Tomaskova ◽  
Lucia Zahradnikova ◽  
...  
Keyword(s):  
Uranyl Acetate ◽  
Ip3 Receptors ◽  
Hek 293 ◽  
Hek 293 Cells ◽  
293 Cells ◽  
Induced Apoptosis

Abstract 16460: Enhanced Trpc Channel-Mediated Ca2+ Influx in the Cells With Phospholipase C-δ1 Overexpression

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Kazuo Murakami ◽  
Tomohiro Osanai ◽  
Makoto Tanaka ◽  
Kimitaka Nishizaki ◽  
Ikuyo Narita ◽  
...  
Keyword(s):  
Phospholipase C ◽  
Transient Receptor Potential ◽  
Coronary Spasm ◽  
Dependent Manner ◽  
Hek 293 ◽  
Trpc Channel ◽  
Hek 293 Cells ◽  
293 Cells ◽  
Dose Dependent

Background: We recently showed that ergometrine induces coronary spasm in the mice with enhanced phospholipase C (PLC)-δ1 activity, which was detected in patients with coronary spasm (Circulation 2012), and PLC-mediated Ca2+ entry is involved in the genesis of coronary spams. We examined the role of enhanced PLC-δ1 in extracellular Ca2+ entry and its underlying mechanisms in human embryonic kidney (HEK)-293 cells and human coronary arteries smooth muscle cells (CASMC). Methods and Results: The cells were stimulated with acetylcholine (ACh) in a extracellular Ca2+-free condition, and the increase in intracellular free Ca2+ concentration ([Ca2+]i) after addition of extracellular Ca2+ was defined as Ca2+ influx. [Ca2+]i was measured by fura-2. In HEK-293 cells, ACh-induced Ca2+ influx (nM ) was 21±2 in the control and 52±6 in the cells with PLC-δ1 overexpression (p<0.05). ACh-induced Ca2+ influx in the cells with PLC-δ1 overexpression was suppressed by nifedipine in a dose-dependent manner but was partially by 36±13% at 10-5M (p<0.05), thereby even after treatment with nifedipine at 10-5M, ACh-induced Ca2+ influx was increased by 2.9±0.1 times by enhanced PLC-δ1 compared with the control (p<0.05). To clarify the role of diacylglycerol (DAG) in Ca2+ influx, the effect of blockers for DAG-activated transient receptor potential (TRPC) channel was examined. ACh-induced Ca2+ influx in the cells with PLC-δ1 overexpression was suppressed by 2-APB, an inhibitor of non-selective cation channel TRPC, in a dose-dependent manner, and was almost completely blocked by 89±12% at 10-4M (p<0.05). While TRPC3 siRNA did not affect ACh-induced Ca2+ influx (59±27 vs 75±23 nM, p=ns), TRPC6 siRNA suppressed Ca2+ influx to 37±28 nM (p<0.05). In human CASMC, ACh-induced Ca2+ influx was 41±11 in the control and 64±15 in the cells with PLC-δ1 overexpression (p<0.05). Like HEK-293 cells, pretreatment with nifedipine partially suppressed Ca2+ influx, whereas either 2-APB or TRPC6 siRNA almost completely blocked it. Conclusion: ACh-induced Ca2+ influx, mediated by both voltage-gated Ca2+ channels and non-selective cation channels TRPC6, is enhanced by PLC-δ1 overexpression. Inhibition of TRPC may be effective in enhanced PLC-δ1-mediated coronary spasm.

scholarly journals Small Conductance Ca 2+ ‐Activated K + Channels Formed by the Expression of Rat SK1 and SK2 Genes in HEK 293 Cells

2003 ◽  
Vol 553 (1) ◽  
pp. 13-19 ◽  
Author(s):  
David C. H. Benton ◽  
Alan S. Monaghan ◽  
Ramine Hosseini ◽  
Parmvir K. Bahia ◽  
Dennis G. Haylett ◽  
...  
Keyword(s):  
Hek 293 ◽  
K Channels ◽  
Hek 293 Cells ◽  
293 Cells ◽  
Small Conductance

scholarly journals Statins and Downstream Inhibitors of the Isoprenylation Pathway Increase Type 2 Iodothyronine Deiodinase Activity

Endocrinology ◽  
2012 ◽  
Vol 153 (8) ◽  
pp. 4039-4048 ◽  
Author(s):  
B. T. Miller ◽  
C. B. Ueta ◽  
V. Lau ◽  
K. G. Jacomino ◽  
L. M. Wasserman ◽  
...  
Keyword(s):  
Active Form ◽  
Critical Determinant ◽  
Iodothyronine Deiodinase ◽  
Hek 293 ◽  
Hek 293 Cells ◽  
Reductase Inhibitors ◽  
293 Cells ◽  
Brown Adipose ◽  
Prenyl Transferase

The type 2 iodothyronine selenodeiodinase (D2) is a critical determinant of local thyroid signaling, converting T4 to the active form T3 at the cytoplasmic face of the endoplasmic reticulum, thus supplying the nucleus with T3 without immediately affecting circulating thyroid hormone levels. Although inhibitors of the cholesterol synthesis/isoprenylation pathway, such as hydroxy-methyl-glutaryl-coenzyme A reductase inhibitors (statins) have been to shown to down-regulate selenoproteins via interruption of normal selenocysteine incorporation, little is known about the effect of statins on D2. Here, we report that statins and prenyl transferase inhibitors actually increase D2 activity in cells with endogenous D2 expression. Although we confirmed that lovastatin (LVS) decreases the activity of transiently expressed D2 in HEK-293 cells, the prenyl transferase inhibitors increase activity in this system as well. LVS treatment increases endogenous Dio2 mRNA in MSTO-211H cells but does not alter transiently expressed Dio2 mRNA in HEK-293 cells. The prenyl transferase inhibitors do not increase Dio2 mRNA in either system, indicating that a posttranscriptional mechanism must exist. Cotreatment with LVS or the prenyl transferase inhibitors with the proteasome inhibitor MG-132 did not lead to additive increases in D2 activity, indirectly implicating the ubiquitin-proteasomal system in the mechanism. Finally, C57BL/6J mice treated with LVS or farnesyl transferase inhibitor-277 for 24 h exhibited increased D2 activity in their brown adipose tissue. These data indicate that statins and downstream inhibitors of the isoprenylation pathway may increase thyroid signaling via stimulation of D2 activity.

scholarly journals Structure Confirmation and Evaluation of a Nonsteroidal Inhibitor of 17β-Hydroxysteroid Dehydrogenase Type 10

2018 ◽  
Vol 4 (3) ◽  
pp. 32 ◽  
Author(s):  
Sophie Boutin ◽  
Donald Poirier
Keyword(s):  
Hydroxysteroid Dehydrogenase ◽  
One Pot ◽  
Intact Cells ◽  
Hek 293 ◽  
Biological Assays ◽  
13C Nuclear Magnetic Resonance ◽  
Dependent Inhibition ◽  
Dose Dependent Inhibition ◽  
Dose Dependent

17β-Hydroxysteroid dehydrogenase type 10 (17β-HSD10) is a steroidogenesis enzyme known for its potential role in Alzheimer’s disease. For comparison purposes between steroidal and nonsteroidal 17β-HSD10 inhibitors 1 and 2, respectively, we attempted the chemical synthesis of benzothiazole phosphonate derivative 2. Instead of a one-pot synthesis, we report a two-step synthesis with characterization of both imine intermediate 5 and final compound 2. Furthermore, complete assignation of 1H and 13C nuclear magnetic resonance (NMR) signals of 2 is provided, as we observed a divergence of NMR data with those published previously. Finally, biological assays showed that 1 and 2 inhibited the oxidation of estradiol (E2) into estrone (E1) by the 17β-HSD10 recombinant protein. However, in human embryonic kidney (HEK)-293 intact cells transfected with 17β-HSD10, only the steroidal inhibitor 1 induced a dose-dependent inhibition of E2 to E1 transformation.

scholarly journals Ondansetron blocks wild-type and p.F503L variant small-conductance Ca2+-activated K+ channels

2018 ◽  
Vol 315 (2) ◽  
pp. H375-H388 ◽  
Author(s):  
Jum-Suk Ko ◽  
Shuai Guo ◽  
Jonathan Hassel ◽  
Patricia Celestino-Soper ◽  
Ty C. Lynnes ◽  
...  
Keyword(s):  
Long Qt Syndrome ◽  
Qt Interval ◽  
Wild Type ◽  
Long Qt ◽  
Drug Induced ◽  
Hek 293 ◽  
Hek 293 Cells ◽  
293 Cells ◽  
Qt Syndrome ◽  
Small Conductance

Apamin-sensitive small-conductance Ca2+-activated K+ (SK) current ( IKAS) is encoded by Ca2+-activated K+ channel subfamily N ( KCNN) genes. IKAS importantly contributes to cardiac repolarization in conditions associated with reduced repolarization reserve. To test the hypothesis that IKAS inhibition contributes to drug-induced long QT syndrome (diLQTS), we screened for KCNN variants among patients with diLQTS, determined the properties of heterologously expressed wild-type (WT) and variant KCNN channels, and determined if the 5-HT3 receptor antagonist ondansetron blocks IKAS. We searched 2,306,335 records in the Indiana Network for Patient Care and found 11 patients with diLQTS who had DNA available in the Indiana Biobank. DNA sequencing discovered a heterozygous KCNN2 variant (p.F503L) in a 52-yr-old woman presenting with corrected QT interval prolongation at baseline (473 ms) and further corrected QT interval lengthening (601 ms) after oral administration of ondansetron. That patient was also heterozygous for the p.S38G and p.P2835S variants of the QT-controlling genes KCNE1 and ankyrin 2, respectively. Patch-clamp experiments revealed that the p.F503L KCNN2 variant heterologously expressed in human embryonic kidney (HEK)-293 cells augmented Ca2+ sensitivity, increasing IKAS density. The fraction of total F503L-KCNN2 protein retained in the membrane was higher than that of WT KCNN2 protein. Ondansetron at nanomolar concentrations inhibited WT and p.F503L SK2 channels expressed in HEK-293 cells as well as native SK channels in ventricular cardiomyocytes. Ondansetron-induced IKAS inhibition was also demonstrated in Langendorff-perfused murine hearts. In conclusion, the heterozygous p.F503L KCNN2 variant increases Ca2+ sensitivity and IKAS density in transfected HEK-293 cells. Ondansetron at therapeutic (i.e., nanomolar) concentrations is a potent IKAS blocker. NEW & NOTEWORTHY We showed that ondansetron, a 5-HT3 receptor antagonist, blocks small-conductance Ca2+-activated K+ (SK) current. Ondansetron may be useful in controlling arrhythmias in which increased SK current is a likely contributor. However, its SK-blocking effects may also facilitate the development of drug-induced long QT syndrome.

scholarly journals Rapid desensitization of the thyrotropin-releasing hormone receptor expressed in single human embryonal kidney 293 cells

1995 ◽  
Vol 311 (2) ◽  
pp. 385-392 ◽  
Author(s):  
L Anderson ◽  
C L Alexander ◽  
E Faccenda ◽  
K A Eidne
Keyword(s):  
Hormone Receptor ◽  
Cyclopiazonic Acid ◽  
Thyrotropin Releasing Hormone ◽  
Receptor Desensitization ◽  
Hek 293 ◽  
Releasing Hormone ◽  
Hek 293 Cells ◽  
C Terminus ◽  
293 Cells ◽  
Dose Dependent

This study uses fluorescence microscopy combined with dynamic video imaging to examine the events associated with the rapid desensitization of the thyrotropin-releasing hormone receptor (TRH-R). In single non-pituitary human embryonic kidney 293 (HEK-293) cells, expressing either the rat or human TRH-Rs, TRH produced a rapid dose-dependent monophasic rise in [Ca2+]i. This Ca2+ transient was completely abolished by pretreatment of cells with the intracellular Ca2+ antagonists thapsigargin or cyclopiazonic acid, but not EGTA, the voltage-operated Ca2+ channel (VOCC) antagonist nifedipine or the second-messenger-operated Ca2+ channel antagonist SK&F 96365. These results suggest that TRH causes the mobilization of Ca2+ from thapsigargin/cyclopiazonic acid-sensitive intracellular Ca2+ stores but not the influx of extracellular Ca2+. HEK-293 cells also failed to respond to KCl or the slow Ca(2+)-channel activator BAY K 8644, suggesting that they lack L-type VOCCs. Rat and human TRH-Rs are highly conserved except at the C-terminus where the sequence differs. The C-terminus is believed to be important in receptor desensitization. Despite differences in this region, rat and human TRH-Rs expressed in HEK-293 cells underwent rapid (within 1 min) desensitization. This desensitization was dose-dependent and did not involve receptor loss. Similarly the bradykinin receptor endogenous to HEK-293 cells also displays a rapid desensitization. We conclude that in TRH-R-expressing non-pituitary HEK-293 cells, TRH mobilizes intracellular Ca2+ resulting in a monophasic Ca2+ transient. The rat and human TRH-Rs as well as the endogenous bradykinin receptor also displayed rapid receptor desensitization.

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