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Kwankyu Park - One of the best experts on this subject based on the ideXlab platform.

  • apamin suppresses biliary fibrosis and activation of hepatic stellate cells
    International Journal of Molecular Medicine, 2017
    Co-Authors: Hyunjin An, Yoonyub Park, Kyung-duck Park, Kwankyu Park
    Abstract:

    : Cholestatic liver disease is characterized by the progressive destruction of biliary epithelial cells (BECs) followed by fibrosis, cirrhosis and liver failure. Activated hepatic stellate cells (HSCs) and portal fibroblasts are the major cellular effectors of enhanced collagen deposition in biliary fibrosis. Apamin, an 18 amino acid peptide neurotoxin found in apitoxin (bee venom), is known to block Ca2+-activated K+ channels and prevent carbon tetrachloride-induced liver fibrosis. In the present study, we aimed to ascertain whether apamin inhibits biliary fibrosis and the proliferation of HSCs. Cholestatic liver fibrosis was established in mouse models with 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) feeding. Cellular assays were performed on HSC-T6 cells (rat immortalized HSCs). DDC feeding led to increased hepatic damage and proinflammtory cytokine levels. Notably, apamin treatment resulted in decreased liver injury and proinflammatory cytokine levels. Moreover, apamin suppressed the deposition of collagen, proliferation of BECs and expression of fibrogenic genes in the DDC-fed mice. In HSCs, apamin suppressed activation of HSCs by inhibiting the Smad signaling pathway. These data suggest that apamin may be a potential therapeutic target in cholestatic liver disease.

  • apamin inhibits tnf α and ifn γ induced inflammatory cytokines and chemokines via suppressions of nf κb signaling pathway and stat in human keratinocytes
    Pharmacological Reports, 2017
    Co-Authors: Hyunjin An, Mi-gyeong Gwon, Hyemin Gu, Kyung-duck Park, Ji Y Park, Kwankyu Park
    Abstract:

    Abstract Background Atopic dermatitis (AD) is identified by an increase in infiltrations of several inflammatory cells including type 2 helper (Th2) lymphocytes. Th2-related chemokines such as thymus and activation-regulated chemokine (TARC/CCL17) and macrophage-derived chemokine (MDC/CCL22), and pro-inflammatory cytokines including interleukin (IL)-1β and IL-6 are considered to play a crucial role in AD. Tumor necrosis factor (TNF)-α- and interferon (IFN)-γ induce the inflammatory condition through production of TARC, MDC, IL-1β and IL-6, and activations of related transcription factors, such as nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and signal transducer and activator of transcription (STAT) in keratinocytes. Apamin, a peptide component of bee venom, has been reported its beneficial activities in various diseases. However, anti-inflammatory effects of apamin on inflammatory condition in keratinocytes have not been explored. Therefore, the present study aimed to demonstrate the anti-inflammatory effect of apamin on TNF-α- and IFN-γ-induced inflammatory condition in keratinocytes. Methods HaCaT was used as human keratinocytes cell line. Cell Counting Kit-8 was performed to measure a cytotoxicity of apamin. The effects of apamin on TNF-α-/IFN-γ-induced inflammatory condition were determined by real-time PCR and Western blot analysis. Further, NF-κB signaling pathways, STAT1, and STAT3 were analyzed by Western blot and immunofluorescence. Results Apamin ameliorated the inflammatory condition through suppression of Th2-related chemokines and pro-inflammatory cytokines. Further, apamin down-regulated the activations of NF-κB signaling pathways and STATs in HaCaT cells. Conclusions These results suggest that apamin has therapeutic effect on AD through improvement of inflammatory condition.

  • apamin inhibits pdgf bb induced vascular smooth muscle cell proliferation and migration through suppressions of activated akt and erk signaling pathway
    Vascular Pharmacology, 2015
    Co-Authors: Hyunjin An, Yoonyub Park, Kwankyu Park
    Abstract:

    Abstract The increased proliferation and migration of vascular smooth muscle cells (VSMC) are key process in the development of atherosclerosis lesions. Platelet-derived growth factor (PDGF) initiates a multitude of biological effects that contribute to VSMC proliferation and migration. Apamin, a component of bee venom, has been known to block the Ca 2 + -activated K + channels. However, the effects of apamin in the regulation PDGF-BB-induced VSMC proliferation and migration has not been identified. In this study, we investigate the inhibitory effect of apamin on PDGF-BB-induced VSMC proliferation and migration. Apamin suppressed the PDGF-BB-induced VSMC proliferation and migration with no apparent cytotoxic effect. In accordance with these findings, apamin induced the arrest of cell cycle progression at G0/G1 phase. Apamin also decreased the expressions of G0/G1 specific regulatory proteins including proliferating cell nuclear antigen (PCNA), cyclin D1, cyclin-dependent kinases (CDK) 4, cyclin E and CDK2, as well as increased the expression of p21 Cip1 in PDGF-BB-induced VSMC. Moreover, apamin inhibited PDGF-BB-induced phosphorylation of Akt and Erk1/2. These results suggest that apamin plays an important role in prevention of vascular proliferation and migration through the G0/G1 cell cycle arrest by PDGF signaling pathway. Thus, apamin may be a promising candidate for the therapy of atherosclerosis.

  • apamin inhibits pdgf bb induced vascular smooth muscle cell proliferation and migration through suppressions of activated akt and erk signaling pathway
    Vascular Pharmacology, 2015
    Co-Authors: Hyunjin An, Yoonyub Park, Kwankyu Park
    Abstract:

    Abstract The increased proliferation and migration of vascular smooth muscle cells (VSMC) are key process in the development of atherosclerosis lesions. Platelet-derived growth factor (PDGF) initiates a multitude of biological effects that contribute to VSMC proliferation and migration. Apamin, a component of bee venom, has been known to block the Ca 2 + -activated K + channels. However, the effects of apamin in the regulation PDGF-BB-induced VSMC proliferation and migration has not been identified. In this study, we investigate the inhibitory effect of apamin on PDGF-BB-induced VSMC proliferation and migration. Apamin suppressed the PDGF-BB-induced VSMC proliferation and migration with no apparent cytotoxic effect. In accordance with these findings, apamin induced the arrest of cell cycle progression at G0/G1 phase. Apamin also decreased the expressions of G0/G1 specific regulatory proteins including proliferating cell nuclear antigen (PCNA), cyclin D1, cyclin-dependent kinases (CDK) 4, cyclin E and CDK2, as well as increased the expression of p21 Cip1 in PDGF-BB-induced VSMC. Moreover, apamin inhibited PDGF-BB-induced phosphorylation of Akt and Erk1/2. These results suggest that apamin plays an important role in prevention of vascular proliferation and migration through the G0/G1 cell cycle arrest by PDGF signaling pathway. Thus, apamin may be a promising candidate for the therapy of atherosclerosis.

  • apamin inhibits hepatic fibrosis through suppression of transforming growth factor β1 induced hepatocyte epithelial mesenchymal transition
    Biochemical and Biophysical Research Communications, 2014
    Co-Authors: Hyunjin An, Kwankyu Park
    Abstract:

    Abstract Apamin is an integral part of bee venom, as a peptide component. It has long been known as a highly selective block Ca2+-activated K+ (SK) channels. However, the cellular mechanism and anti-fibrotic effect of apamin in TGF-β1-induced hepatocytes have not been explored. In the present study, we investigated the anti-fibrosis or anti-EMT mechanism by examining the effect of apamin on TGF-β1-induced hepatocytes. AML12 cells were seeded at ∼60% confluence in complete growth medium. Twenty-four hours later, the cells were changed to serum free medium containing the indicated concentrations of apamin. After 30 min, the cells were treated with 2 ng/ml of TGF-β1 and co-cultured for 48 h. Also, we investigated the effects of apamin on the CCl4-induced liver fibrosis animal model. Treatment of AML12 cells with 2 ng/ml of TGF-β1 resulted in loss of E-cadherin protein at the cell–cell junctions and concomitant increased expression of vimentin. In addition, phosphorylation levels of ERK1/2, Akt, Smad2/3 and Smad4 were increased by TGF-β1 stimulation. However, cells treated concurrently with TGF-β1 and apamin retained high levels of localized expression of E-cadherin and showed no increase in vimentin. Specifically, treatment with 2 μg/ml of apamin almost completely blocked the phosphorylation of ERK1/2, Akt, Smad2/3 and Smad4 in AML12 cells. In addition, apamin exhibited prevention of pathological changes in the CCl4-injected animal models. These results demonstrate the potential of apamin for the prevention of EMT progression induced by TGF-β1 in vitro and CCl4-injected in vivo.

Hyunjin An - One of the best experts on this subject based on the ideXlab platform.

  • apamin suppresses biliary fibrosis and activation of hepatic stellate cells
    International Journal of Molecular Medicine, 2017
    Co-Authors: Hyunjin An, Yoonyub Park, Kyung-duck Park, Kwankyu Park
    Abstract:

    : Cholestatic liver disease is characterized by the progressive destruction of biliary epithelial cells (BECs) followed by fibrosis, cirrhosis and liver failure. Activated hepatic stellate cells (HSCs) and portal fibroblasts are the major cellular effectors of enhanced collagen deposition in biliary fibrosis. Apamin, an 18 amino acid peptide neurotoxin found in apitoxin (bee venom), is known to block Ca2+-activated K+ channels and prevent carbon tetrachloride-induced liver fibrosis. In the present study, we aimed to ascertain whether apamin inhibits biliary fibrosis and the proliferation of HSCs. Cholestatic liver fibrosis was established in mouse models with 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) feeding. Cellular assays were performed on HSC-T6 cells (rat immortalized HSCs). DDC feeding led to increased hepatic damage and proinflammtory cytokine levels. Notably, apamin treatment resulted in decreased liver injury and proinflammatory cytokine levels. Moreover, apamin suppressed the deposition of collagen, proliferation of BECs and expression of fibrogenic genes in the DDC-fed mice. In HSCs, apamin suppressed activation of HSCs by inhibiting the Smad signaling pathway. These data suggest that apamin may be a potential therapeutic target in cholestatic liver disease.

  • apamin inhibits tnf α and ifn γ induced inflammatory cytokines and chemokines via suppressions of nf κb signaling pathway and stat in human keratinocytes
    Pharmacological Reports, 2017
    Co-Authors: Hyunjin An, Mi-gyeong Gwon, Hyemin Gu, Kyung-duck Park, Ji Y Park, Kwankyu Park
    Abstract:

    Abstract Background Atopic dermatitis (AD) is identified by an increase in infiltrations of several inflammatory cells including type 2 helper (Th2) lymphocytes. Th2-related chemokines such as thymus and activation-regulated chemokine (TARC/CCL17) and macrophage-derived chemokine (MDC/CCL22), and pro-inflammatory cytokines including interleukin (IL)-1β and IL-6 are considered to play a crucial role in AD. Tumor necrosis factor (TNF)-α- and interferon (IFN)-γ induce the inflammatory condition through production of TARC, MDC, IL-1β and IL-6, and activations of related transcription factors, such as nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and signal transducer and activator of transcription (STAT) in keratinocytes. Apamin, a peptide component of bee venom, has been reported its beneficial activities in various diseases. However, anti-inflammatory effects of apamin on inflammatory condition in keratinocytes have not been explored. Therefore, the present study aimed to demonstrate the anti-inflammatory effect of apamin on TNF-α- and IFN-γ-induced inflammatory condition in keratinocytes. Methods HaCaT was used as human keratinocytes cell line. Cell Counting Kit-8 was performed to measure a cytotoxicity of apamin. The effects of apamin on TNF-α-/IFN-γ-induced inflammatory condition were determined by real-time PCR and Western blot analysis. Further, NF-κB signaling pathways, STAT1, and STAT3 were analyzed by Western blot and immunofluorescence. Results Apamin ameliorated the inflammatory condition through suppression of Th2-related chemokines and pro-inflammatory cytokines. Further, apamin down-regulated the activations of NF-κB signaling pathways and STATs in HaCaT cells. Conclusions These results suggest that apamin has therapeutic effect on AD through improvement of inflammatory condition.

  • apamin inhibits pdgf bb induced vascular smooth muscle cell proliferation and migration through suppressions of activated akt and erk signaling pathway
    Vascular Pharmacology, 2015
    Co-Authors: Hyunjin An, Yoonyub Park, Kwankyu Park
    Abstract:

    Abstract The increased proliferation and migration of vascular smooth muscle cells (VSMC) are key process in the development of atherosclerosis lesions. Platelet-derived growth factor (PDGF) initiates a multitude of biological effects that contribute to VSMC proliferation and migration. Apamin, a component of bee venom, has been known to block the Ca 2 + -activated K + channels. However, the effects of apamin in the regulation PDGF-BB-induced VSMC proliferation and migration has not been identified. In this study, we investigate the inhibitory effect of apamin on PDGF-BB-induced VSMC proliferation and migration. Apamin suppressed the PDGF-BB-induced VSMC proliferation and migration with no apparent cytotoxic effect. In accordance with these findings, apamin induced the arrest of cell cycle progression at G0/G1 phase. Apamin also decreased the expressions of G0/G1 specific regulatory proteins including proliferating cell nuclear antigen (PCNA), cyclin D1, cyclin-dependent kinases (CDK) 4, cyclin E and CDK2, as well as increased the expression of p21 Cip1 in PDGF-BB-induced VSMC. Moreover, apamin inhibited PDGF-BB-induced phosphorylation of Akt and Erk1/2. These results suggest that apamin plays an important role in prevention of vascular proliferation and migration through the G0/G1 cell cycle arrest by PDGF signaling pathway. Thus, apamin may be a promising candidate for the therapy of atherosclerosis.

  • apamin inhibits pdgf bb induced vascular smooth muscle cell proliferation and migration through suppressions of activated akt and erk signaling pathway
    Vascular Pharmacology, 2015
    Co-Authors: Hyunjin An, Yoonyub Park, Kwankyu Park
    Abstract:

    Abstract The increased proliferation and migration of vascular smooth muscle cells (VSMC) are key process in the development of atherosclerosis lesions. Platelet-derived growth factor (PDGF) initiates a multitude of biological effects that contribute to VSMC proliferation and migration. Apamin, a component of bee venom, has been known to block the Ca 2 + -activated K + channels. However, the effects of apamin in the regulation PDGF-BB-induced VSMC proliferation and migration has not been identified. In this study, we investigate the inhibitory effect of apamin on PDGF-BB-induced VSMC proliferation and migration. Apamin suppressed the PDGF-BB-induced VSMC proliferation and migration with no apparent cytotoxic effect. In accordance with these findings, apamin induced the arrest of cell cycle progression at G0/G1 phase. Apamin also decreased the expressions of G0/G1 specific regulatory proteins including proliferating cell nuclear antigen (PCNA), cyclin D1, cyclin-dependent kinases (CDK) 4, cyclin E and CDK2, as well as increased the expression of p21 Cip1 in PDGF-BB-induced VSMC. Moreover, apamin inhibited PDGF-BB-induced phosphorylation of Akt and Erk1/2. These results suggest that apamin plays an important role in prevention of vascular proliferation and migration through the G0/G1 cell cycle arrest by PDGF signaling pathway. Thus, apamin may be a promising candidate for the therapy of atherosclerosis.

  • apamin inhibits hepatic fibrosis through suppression of transforming growth factor β1 induced hepatocyte epithelial mesenchymal transition
    Biochemical and Biophysical Research Communications, 2014
    Co-Authors: Hyunjin An, Kwankyu Park
    Abstract:

    Abstract Apamin is an integral part of bee venom, as a peptide component. It has long been known as a highly selective block Ca2+-activated K+ (SK) channels. However, the cellular mechanism and anti-fibrotic effect of apamin in TGF-β1-induced hepatocytes have not been explored. In the present study, we investigated the anti-fibrosis or anti-EMT mechanism by examining the effect of apamin on TGF-β1-induced hepatocytes. AML12 cells were seeded at ∼60% confluence in complete growth medium. Twenty-four hours later, the cells were changed to serum free medium containing the indicated concentrations of apamin. After 30 min, the cells were treated with 2 ng/ml of TGF-β1 and co-cultured for 48 h. Also, we investigated the effects of apamin on the CCl4-induced liver fibrosis animal model. Treatment of AML12 cells with 2 ng/ml of TGF-β1 resulted in loss of E-cadherin protein at the cell–cell junctions and concomitant increased expression of vimentin. In addition, phosphorylation levels of ERK1/2, Akt, Smad2/3 and Smad4 were increased by TGF-β1 stimulation. However, cells treated concurrently with TGF-β1 and apamin retained high levels of localized expression of E-cadherin and showed no increase in vimentin. Specifically, treatment with 2 μg/ml of apamin almost completely blocked the phosphorylation of ERK1/2, Akt, Smad2/3 and Smad4 in AML12 cells. In addition, apamin exhibited prevention of pathological changes in the CCl4-injected animal models. These results demonstrate the potential of apamin for the prevention of EMT progression induced by TGF-β1 in vitro and CCl4-injected in vivo.

Peng-sheng Chen - One of the best experts on this subject based on the ideXlab platform.

  • Small-conductance calcium-activated potassium current modulates the ventricular escape rhythm in normal rabbit hearts
    Heart Rhythm, 2018
    Co-Authors: Mu Chen, Michael Rubart-von Der Lohe, Thomas H Everett, Zhilin Qu, James N. Weiss, Changyu Shen, Zhuo Wang, Penelope A. Boyden, Peng-sheng Chen
    Abstract:

    Background The apamin-sensitive small-conductance calcium-activated K (SK) current IKAS modulates automaticity of the sinus node. IKAS blockade by apamin causes sinus bradycardia. Objective The purpose of this study was to test the hypothesis that IKAS modulates ventricular automaticity. Methods We tested the effects of apamin (100 nM) on ventricular escape rhythms in Langendorff-perfused rabbit ventricles with atrioventricular block (protocol 1) and on recorded transmembrane action potential of pseudotendons of superfused right ventricular endocardial preparations (protocol 2). Results All preparations exhibited spontaneous ventricular escape rhythms. In protocol 1, apamin decreased the atrial rate from 186.2 ± 18.0 bpm to 163.8 ± 18.7 bpm (N = 6; P = .006) but accelerated the ventricular escape rate from 51.5 ± 10.7 bpm to 98.2 ± 25.4 bpm (P = .031). Three preparations exhibited bursts of nonsustained ventricular tachycardia and pauses, resulting in repeated burst termination pattern. In protocol 2, apamin increased the ventricular escape rate from 70.2 ± 13.1 bpm to 110.1 ± 2.2 bpm (P = .035). Spontaneous phase 4 depolarization was recorded from the pseudotendons in 6 of 10 preparations at baseline and in 3 in the presence of apamin. There were no changes of phase 4 slope (18.37 ± 3.55 mV/s vs 18.93 ± 3.26 mV/s, N=3; P = .231, ), but the threshold of phase 0 activation (mV) reduced from –67.97 ± 1.53 to –75.26 ± 0.28 (P = .034). Addition of JTV-519, a ryanodine receptor 2 stabilizer, in 5 preparations reduced escape rate back to baseline. Conclusion Contrary to its bradycardic effect in the sinus node, IKAS blockade by apamin accelerates ventricular automaticity and causes repeated nonsustained ventricular tachycardia in normal ventricles. ryanodine receptor 2 blockade reversed the apamin effects on ventricular automaticity.

  • apamin does not inhibit human cardiac na current l type ca2 current or other major k currents
    PLOS ONE, 2014
    Co-Authors: Chihchieh Yu, Tomohiko Ai, James N. Weiss, Peng-sheng Chen
    Abstract:

    Author(s): Yu, Chih-Chieh; Ai, Tomohiko; Weiss, James N; Chen, Peng-Sheng | Abstract: Apamin is commonly used as a small-conductance Ca2+-activated K+ (SK) current inhibitor. However, the specificity of apamin in cardiac tissues remains unclear.To test the hypothesis that apamin does not inhibit any major cardiac ion currents.We studied human embryonic kidney (HEK) 293 cells that expressed human voltage-gated Na+, K+ and Ca2+ currents and isolated rabbit ventricular myocytes. Whole-cell patch clamp techniques were used to determine ionic current densities before and after apamin administration.Ca2+ currents (CACNA1c+CACNB2b) were not affected by apamin (500 nM) (data are presented as median [25th percentile;75th percentile] (from -16 [-20;-10] to -17 [-19;-13] pA/pF, P = NS), but were reduced by nifedipine to -1.6 [-3.2;-1.3] pA/pF (p = 0.008). Na+ currents (SCN5A) were not affected by apamin (from -261 [-282;-145] to -268 [-379;-132] pA/pF, P = NS), but were reduced by flecainide to -57 [-70;-47] pA/pF (p = 0.018). None of the major K+ currents (IKs, IKr, IK1 and Ito) were inhibited by 500 nM of apamin (KCNQ1+KCNE1, from 28 [20]; [37] to 23 [18]; [32] pA/pF; KCNH2+KCNE2, from 28 [24]; [30] to 27 [24]; [29] pA/pF; KCNJ2, from -46 [-48;-40] to -46 [-51;-35] pA/pF; KCND3, from 608 [505;748] to 606 [454;684]). Apamin did not inhibit the INa or ICaL in isolated rabbit ventricular myocytes (INa, from -67 [-75;-59] to -68 [-71;-59] pA/pF; ICaL, from -16 [-17;-14] to -14 [-15;-13] pA/pF, P = NS for both).Apamin does not inhibit human cardiac Na+ currents, L-type Ca2+ currents or other major K+ currents. These findings indicate that apamin is a specific SK current inhibitor in hearts as well as in other organs.

  • apamin does not inhibit human cardiac na current l type ca2 current or other major k currents
    PLOS ONE, 2014
    Co-Authors: Chihchieh Yu, Tomohiko Ai, James N. Weiss, Peng-sheng Chen
    Abstract:

    Author(s): Yu, Chih-Chieh; Ai, Tomohiko; Weiss, James N; Chen, Peng-Sheng | Abstract: Apamin is commonly used as a small-conductance Ca2+-activated K+ (SK) current inhibitor. However, the specificity of apamin in cardiac tissues remains unclear.To test the hypothesis that apamin does not inhibit any major cardiac ion currents.We studied human embryonic kidney (HEK) 293 cells that expressed human voltage-gated Na+, K+ and Ca2+ currents and isolated rabbit ventricular myocytes. Whole-cell patch clamp techniques were used to determine ionic current densities before and after apamin administration.Ca2+ currents (CACNA1c+CACNB2b) were not affected by apamin (500 nM) (data are presented as median [25th percentile;75th percentile] (from -16 [-20;-10] to -17 [-19;-13] pA/pF, P = NS), but were reduced by nifedipine to -1.6 [-3.2;-1.3] pA/pF (p = 0.008). Na+ currents (SCN5A) were not affected by apamin (from -261 [-282;-145] to -268 [-379;-132] pA/pF, P = NS), but were reduced by flecainide to -57 [-70;-47] pA/pF (p = 0.018). None of the major K+ currents (IKs, IKr, IK1 and Ito) were inhibited by 500 nM of apamin (KCNQ1+KCNE1, from 28 [20]; [37] to 23 [18]; [32] pA/pF; KCNH2+KCNE2, from 28 [24]; [30] to 27 [24]; [29] pA/pF; KCNJ2, from -46 [-48;-40] to -46 [-51;-35] pA/pF; KCND3, from 608 [505;748] to 606 [454;684]). Apamin did not inhibit the INa or ICaL in isolated rabbit ventricular myocytes (INa, from -67 [-75;-59] to -68 [-71;-59] pA/pF; ICaL, from -16 [-17;-14] to -14 [-15;-13] pA/pF, P = NS for both).Apamin does not inhibit human cardiac Na+ currents, L-type Ca2+ currents or other major K+ currents. These findings indicate that apamin is a specific SK current inhibitor in hearts as well as in other organs.

  • Effects of apamin on IKs and IKr in transfected HEK 293 cells.
    2014
    Co-Authors: James N. Weiss, Peng-sheng Chen
    Abstract:

    (A) The representative tracings of IKs obtained by pulse protocol shown in the inset before apamin (a), after apamin (b) and after chromanol (c) at time points indicated by arrows a through c, respectively, in (B). (B) The time course of peak IKs at 40 mV. (C) The summary of drug effects normalized to baseline. (D) The representative tracings of IKr obtained by a pulse protocol shown in the inset before apamin (a), after apamin (b) and after E4031 (c) at time points indicated by arrows a through c in (E). (E) The time course of peak IKr at 20 mV. (F) The summary of drug effects normalized to baseline.

  • apamin sensitive potassium current modulates action potential duration restitution and arrhythmogenesis of failing rabbit ventricles
    Circulation-arrhythmia and Electrophysiology, 2013
    Co-Authors: Yu Cheng Hsieh, Chia Hsiang Hsueh, Po Cheng Chang, Tomohiko Ai, Zhenhui Chen, James N. Weiss, Changyu Shen, Peng-sheng Chen
    Abstract:

    Background— Apamin-sensitive K currents ( I KAS) are upregulated in heart failure. We hypothesize that apamin can flatten action potential duration restitution (APDR) curve and can reduce ventricular fibrillation duration in failing ventricles. Methods and Results— We simultaneously mapped membrane potential and intracellular Ca (Cai) in 7 rabbit hearts with pacing-induced heart failure and in 7 normal hearts. A dynamic pacing protocol was used to determine APDR at baseline and after apamin (100 nmol/L) infusion. Apamin did not change APD80 in normal ventricles, but prolonged APD80 in failing ventricles at either long (≥300 ms) or short (≤170 ms) pacing cycle length, but not at intermediate pacing cycle length. The maximal slope of APDR curve was 2.03 (95% confidence interval, 1.73–2.32) in failing ventricles and 1.26 (95% confidence interval, 1.13–1.40) in normal ventricles at baseline ( P =0.002). After apamin administration, the maximal slope of APDR in failing ventricles decreased to 1.43 (95% confidence interval, 1.01–1.84; P =0.018), whereas no significant changes were observed in normal ventricles. During ventricular fibrillation in failing ventricles, the number of phase singularities (baseline versus apamin, 4.0 versus 2.5), dominant frequency (13.0 versus 10.0 Hz), and ventricular fibrillation duration (160 versus 80 s) were all significantly ( P <0.05) decreased by apamin. Conclusions— Apamin prolongs APD at long and short, but not at intermediate pacing cycle length in failing ventricles. I KAS upregulation may be antiarrhythmic by preserving the repolarization reserve at slow heart rate, but is proarrhythmic by steepening the slope of APDR curve, which promotes the generation and maintenance of ventricular fibrillation.

Yoonyub Park - One of the best experts on this subject based on the ideXlab platform.

  • apamin suppresses biliary fibrosis and activation of hepatic stellate cells
    International Journal of Molecular Medicine, 2017
    Co-Authors: Hyunjin An, Yoonyub Park, Kyung-duck Park, Kwankyu Park
    Abstract:

    : Cholestatic liver disease is characterized by the progressive destruction of biliary epithelial cells (BECs) followed by fibrosis, cirrhosis and liver failure. Activated hepatic stellate cells (HSCs) and portal fibroblasts are the major cellular effectors of enhanced collagen deposition in biliary fibrosis. Apamin, an 18 amino acid peptide neurotoxin found in apitoxin (bee venom), is known to block Ca2+-activated K+ channels and prevent carbon tetrachloride-induced liver fibrosis. In the present study, we aimed to ascertain whether apamin inhibits biliary fibrosis and the proliferation of HSCs. Cholestatic liver fibrosis was established in mouse models with 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) feeding. Cellular assays were performed on HSC-T6 cells (rat immortalized HSCs). DDC feeding led to increased hepatic damage and proinflammtory cytokine levels. Notably, apamin treatment resulted in decreased liver injury and proinflammatory cytokine levels. Moreover, apamin suppressed the deposition of collagen, proliferation of BECs and expression of fibrogenic genes in the DDC-fed mice. In HSCs, apamin suppressed activation of HSCs by inhibiting the Smad signaling pathway. These data suggest that apamin may be a potential therapeutic target in cholestatic liver disease.

  • apamin inhibits pdgf bb induced vascular smooth muscle cell proliferation and migration through suppressions of activated akt and erk signaling pathway
    Vascular Pharmacology, 2015
    Co-Authors: Hyunjin An, Yoonyub Park, Kwankyu Park
    Abstract:

    Abstract The increased proliferation and migration of vascular smooth muscle cells (VSMC) are key process in the development of atherosclerosis lesions. Platelet-derived growth factor (PDGF) initiates a multitude of biological effects that contribute to VSMC proliferation and migration. Apamin, a component of bee venom, has been known to block the Ca 2 + -activated K + channels. However, the effects of apamin in the regulation PDGF-BB-induced VSMC proliferation and migration has not been identified. In this study, we investigate the inhibitory effect of apamin on PDGF-BB-induced VSMC proliferation and migration. Apamin suppressed the PDGF-BB-induced VSMC proliferation and migration with no apparent cytotoxic effect. In accordance with these findings, apamin induced the arrest of cell cycle progression at G0/G1 phase. Apamin also decreased the expressions of G0/G1 specific regulatory proteins including proliferating cell nuclear antigen (PCNA), cyclin D1, cyclin-dependent kinases (CDK) 4, cyclin E and CDK2, as well as increased the expression of p21 Cip1 in PDGF-BB-induced VSMC. Moreover, apamin inhibited PDGF-BB-induced phosphorylation of Akt and Erk1/2. These results suggest that apamin plays an important role in prevention of vascular proliferation and migration through the G0/G1 cell cycle arrest by PDGF signaling pathway. Thus, apamin may be a promising candidate for the therapy of atherosclerosis.

  • apamin inhibits pdgf bb induced vascular smooth muscle cell proliferation and migration through suppressions of activated akt and erk signaling pathway
    Vascular Pharmacology, 2015
    Co-Authors: Hyunjin An, Yoonyub Park, Kwankyu Park
    Abstract:

    Abstract The increased proliferation and migration of vascular smooth muscle cells (VSMC) are key process in the development of atherosclerosis lesions. Platelet-derived growth factor (PDGF) initiates a multitude of biological effects that contribute to VSMC proliferation and migration. Apamin, a component of bee venom, has been known to block the Ca 2 + -activated K + channels. However, the effects of apamin in the regulation PDGF-BB-induced VSMC proliferation and migration has not been identified. In this study, we investigate the inhibitory effect of apamin on PDGF-BB-induced VSMC proliferation and migration. Apamin suppressed the PDGF-BB-induced VSMC proliferation and migration with no apparent cytotoxic effect. In accordance with these findings, apamin induced the arrest of cell cycle progression at G0/G1 phase. Apamin also decreased the expressions of G0/G1 specific regulatory proteins including proliferating cell nuclear antigen (PCNA), cyclin D1, cyclin-dependent kinases (CDK) 4, cyclin E and CDK2, as well as increased the expression of p21 Cip1 in PDGF-BB-induced VSMC. Moreover, apamin inhibited PDGF-BB-induced phosphorylation of Akt and Erk1/2. These results suggest that apamin plays an important role in prevention of vascular proliferation and migration through the G0/G1 cell cycle arrest by PDGF signaling pathway. Thus, apamin may be a promising candidate for the therapy of atherosclerosis.

Chihchieh Yu - One of the best experts on this subject based on the ideXlab platform.

  • apamin does not inhibit human cardiac na current l type ca2 current or other major k currents
    PLOS ONE, 2014
    Co-Authors: Chihchieh Yu, Tomohiko Ai, James N. Weiss, Peng-sheng Chen
    Abstract:

    Author(s): Yu, Chih-Chieh; Ai, Tomohiko; Weiss, James N; Chen, Peng-Sheng | Abstract: Apamin is commonly used as a small-conductance Ca2+-activated K+ (SK) current inhibitor. However, the specificity of apamin in cardiac tissues remains unclear.To test the hypothesis that apamin does not inhibit any major cardiac ion currents.We studied human embryonic kidney (HEK) 293 cells that expressed human voltage-gated Na+, K+ and Ca2+ currents and isolated rabbit ventricular myocytes. Whole-cell patch clamp techniques were used to determine ionic current densities before and after apamin administration.Ca2+ currents (CACNA1c+CACNB2b) were not affected by apamin (500 nM) (data are presented as median [25th percentile;75th percentile] (from -16 [-20;-10] to -17 [-19;-13] pA/pF, P = NS), but were reduced by nifedipine to -1.6 [-3.2;-1.3] pA/pF (p = 0.008). Na+ currents (SCN5A) were not affected by apamin (from -261 [-282;-145] to -268 [-379;-132] pA/pF, P = NS), but were reduced by flecainide to -57 [-70;-47] pA/pF (p = 0.018). None of the major K+ currents (IKs, IKr, IK1 and Ito) were inhibited by 500 nM of apamin (KCNQ1+KCNE1, from 28 [20]; [37] to 23 [18]; [32] pA/pF; KCNH2+KCNE2, from 28 [24]; [30] to 27 [24]; [29] pA/pF; KCNJ2, from -46 [-48;-40] to -46 [-51;-35] pA/pF; KCND3, from 608 [505;748] to 606 [454;684]). Apamin did not inhibit the INa or ICaL in isolated rabbit ventricular myocytes (INa, from -67 [-75;-59] to -68 [-71;-59] pA/pF; ICaL, from -16 [-17;-14] to -14 [-15;-13] pA/pF, P = NS for both).Apamin does not inhibit human cardiac Na+ currents, L-type Ca2+ currents or other major K+ currents. These findings indicate that apamin is a specific SK current inhibitor in hearts as well as in other organs.

  • apamin does not inhibit human cardiac na current l type ca2 current or other major k currents
    PLOS ONE, 2014
    Co-Authors: Chihchieh Yu, Tomohiko Ai, James N. Weiss, Peng-sheng Chen
    Abstract:

    Author(s): Yu, Chih-Chieh; Ai, Tomohiko; Weiss, James N; Chen, Peng-Sheng | Abstract: Apamin is commonly used as a small-conductance Ca2+-activated K+ (SK) current inhibitor. However, the specificity of apamin in cardiac tissues remains unclear.To test the hypothesis that apamin does not inhibit any major cardiac ion currents.We studied human embryonic kidney (HEK) 293 cells that expressed human voltage-gated Na+, K+ and Ca2+ currents and isolated rabbit ventricular myocytes. Whole-cell patch clamp techniques were used to determine ionic current densities before and after apamin administration.Ca2+ currents (CACNA1c+CACNB2b) were not affected by apamin (500 nM) (data are presented as median [25th percentile;75th percentile] (from -16 [-20;-10] to -17 [-19;-13] pA/pF, P = NS), but were reduced by nifedipine to -1.6 [-3.2;-1.3] pA/pF (p = 0.008). Na+ currents (SCN5A) were not affected by apamin (from -261 [-282;-145] to -268 [-379;-132] pA/pF, P = NS), but were reduced by flecainide to -57 [-70;-47] pA/pF (p = 0.018). None of the major K+ currents (IKs, IKr, IK1 and Ito) were inhibited by 500 nM of apamin (KCNQ1+KCNE1, from 28 [20]; [37] to 23 [18]; [32] pA/pF; KCNH2+KCNE2, from 28 [24]; [30] to 27 [24]; [29] pA/pF; KCNJ2, from -46 [-48;-40] to -46 [-51;-35] pA/pF; KCND3, from 608 [505;748] to 606 [454;684]). Apamin did not inhibit the INa or ICaL in isolated rabbit ventricular myocytes (INa, from -67 [-75;-59] to -68 [-71;-59] pA/pF; ICaL, from -16 [-17;-14] to -14 [-15;-13] pA/pF, P = NS for both).Apamin does not inhibit human cardiac Na+ currents, L-type Ca2+ currents or other major K+ currents. These findings indicate that apamin is a specific SK current inhibitor in hearts as well as in other organs.