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Byung Joo Kim - One of the best experts on this subject based on the ideXlab platform.
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Depolarization of Pacemaker Potentials by caffeic acid phenethyl ester in interstitial cells of Cajal from the murine small intestine.
Canadian journal of physiology and pharmacology, 2019Co-Authors: Jeong Nam Kim, Byung Joo KimAbstract:Interstitial cells of Cajal (ICCs) are Pacemaker cells in the gastrointestinal (GI) tract and generate Pacemaker Potentials. In this study, we investigated the effects of caffeic acid phenethyl ester (CAPE) on the Pacemaker Potentials of ICCs from the mouse small or large intestine. Using the whole-cell patch-clamp configuration, we found that CAPE depolarized the Pacemaker Potentials of cultured ICCs from the murine small intestine in a dose-dependent manner. The estrogen receptor (ER) β antagonist PHTPP completely inhibited CAPE-induced depolarization, but the ERα antagonist BHPI did not. Intracellular GDP-β-S and pretreatment with Ca2+-free solution or thapsigargin also blocked CAPE-induced depolarization. To investigate the mechanisms of CAPE-mediated depolarization of ICCs, we used the nonselective cation channel (NSCC) inhibitor flufenamic acid, the Cl- channel blocker, mitogen-activated protein kinase (MAPK) inhibitors PD98059, SB203580, or SP600125, and PI3 kinase inhibitor LY294002. All inhibitors blocked the CAPE-induced Pacemaker Potential depolarization of ICCs. These results suggest that CAPE induces Pacemaker Potential depolarization through ERβ in a G protein, NSCC, Cl- channel, MAPK- and PI3 kinase dependent manner via intracellular and extracellular Ca2+ regulation in the murine small intestine. CAPE may therefore modulate GI motility by acting on ICCs in the murine small intestine.
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The Mechanism of Action of Ghrelin and Motilin in the Pacemaker Potentials of Interstitial Cells of Cajal from the Murine Small Intestine.
Molecules and cells, 2019Co-Authors: Jeong Nam Kim, Byung Joo KimAbstract:Interstitial cells of Cajal (ICCs) are Pacemaker cells that exhibit periodic spontaneous depolarization in the gastrointestinal (GI) tract and generate Pacemaker Potentials. In this study, we investigated the effects of ghrelin and motilin on the Pacemaker Potentials of ICCs isolated from the mouse small intestine. Using the whole-cell patch-clamp configuration, we demonstrated that ghrelin depolarized Pacemaker Potentials of cultured ICCs in a dose-dependent manner. The ghrelin receptor antagonist [D-Lys] GHRP-6 completely inhibited this ghrelin-induced depolarization. Intracellular guanosine 5'-diphosphate-β-S and pre-treatment with Ca2+free solution or thapsigargin also blocked the ghrelin-induced depolarization. To investigate the involvement of inositol triphosphate (IP3), Rho kinase, and protein kinase C (PKC) in ghrelin-mediated Pacemaker Potential depolarization of ICCs, we used the IP3 receptor inhibitors 2-aminoethoxydiphenyl borate and xestospongin C, the Rho kinase inhibitor Y-27632, and the PKC inhibitors staurosporine, Go6976, and rottlerin. All inhibitors except rottlerin blocked the ghrelin-induced Pacemaker Potential depolarization of ICCs. In addition, motilin depolarized the Pacemaker Potentials of ICCs in a similar dose-dependent manner as ghrelin, and this was also completely inhibited by [D-Lys] GHRP-6. These results suggest that ghrelin induced the Pacemaker Potential depolarization through the ghrelin receptor in a G protein-, IP3-, Rho kinase-, and PKC-dependent manner via intracellular and extracellular Ca2+ regulation. In addition, motilin was able to depolarize the Pacemaker Potentials of ICCs through the ghrelin receptor. Therefore, ghrelin and its receptor may modulate GI motility by acting on ICCs in the murine small intestine.
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The Traditional Medicine Banhasasim-Tang Depolarizes Pacemaker Potentials of Cultured Interstitial Cells of Cajal through M3 Muscarinic and 5-HT3 Receptors in Murine Small Intestine.
Digestion, 2019Co-Authors: Jeong Nam Kim, Joo Hyun Nam, Jong Rok Lee, Sang-chan Kim, Byung Joo KimAbstract:Background Banhasasim-tang (BHSST) is a classic herbal formulation in traditional Chinese medicine widely used for gastrointestinal (GI) tract motility disorder. We investigated the effects of BHSST on the Pacemaker Potentials of cultured interstitial cells of Cajal (ICCs) in small intestine in vitro and its effects on GI motor functions in vivo. Methods We isolated ICCs from the small intestines and recorded Pacemaker Potentials in cultured ICCs with the whole-cell patch-clamp configuration in vitro. Intestinal transit rates (ITR%) were investigated in normal mice and GI motility dysfunction (GMD) mouse models in vivo. Results BHSST (20-50 mg/mL) depolarized Pacemaker Potentials and decreased their amplitudes in a concentration-dependent manner. Pretreatment with methoctramine (a muscarinic M2 receptor antagonist) did not inhibit BHSST-induced Pacemaker Potential depolarization. However, when we applied 1,1-dimethyl-4-diphenylacetoxypiperidinium iodide (4-DAMP; a muscarinic M3 receptor antagonist), BHSST-induced effects were blocked. Pretreatment with Y25130 (a 5-HT3 receptor antagonist) blocked BHSST-induced effects in ICCs. In addition, when we applied 4-DAMP and Y25130 together, BHSST-induced effects were completely blocked. Pretreatment with Ca2+-free solution or thapsigargin inhibited BHSST-induced effects. Moreover, BHSST blocked both the transient receptor Potential melastatin (TRPM) 7 and voltage-sensitive calcium-activated chloride (anoctamin-1, ANO1) channels. In normal mice, ITR% values were significantly increased by BHSST in a dose-dependent manner. The ITR% of GMD mice was significantly reduced relative to those of normal mice, which were significantly reversed by BHSST in a dose-dependent manner. Conclusion These results suggested that BHSST depolarizes the Pacemaker Potentials of ICCs in a dose-dependent manner through the M3 and 5-HT3 receptors via internal and external Ca2+-dependent and TRPM7- and ANO1-independent pathways in vitro. Moreover, BHSST increased ITR% in vivo in normal mice and GMD mouse models. Taken together, the results of this study showed that BHSST had the Potential for development as a prokinetic agent in GI motility function.
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The Mechanism of Action of Zingerone in the Pacemaker Potentials of Interstitial Cells of Cajal Isolated from Murine Small Intestine.
Cellular Physiology and Biochemistry, 2018Co-Authors: Jung Nam Kim, Hyun Jung Kim, Iksung Kim, Yun Tai Kim, Byung Joo KimAbstract:Background/aims Zingerone, a major component found in ginger root, is clinically effective for the treatment of various diseases. Interstitial cells of Cajal (ICCs) are the Pacemaker cells responsible for slow waves in the gastrointestinal (GI) tract. We investigated the effects of zingerone on the Pacemaker Potentials of ICCs to assess its mechanisms of action and its Potential as a treatment for GI tract motility disorder. Methods We isolated ICCs from small intestines, and the whole-cell patch-clamp configuration was used to record the Pacemaker Potentials in cultured ICCs. Results Under the current clamping mode, zingerone inhibited Pacemaker Potentials of ICCs concentration-dependently. These effects were blocked not by capsazepine, a transient receptor Potential vanilloid 1 (TRPV1) channel blocker, but by glibenclamide, a specific ATP-sensitive K+ channel blocker. Pretreatment with SQ-22536 (an adenylate cyclase inhibitor), LY294002 (a phosphoinositide 3-kinase inhibitor), and calphostin C (a protein kinase C (PKC) inhibitor) did not block the effects of zingerone on the Pacemaker Potentials relative to treatment with zingerone alone. However, zingerone-induced Pacemaker Potential inhibition was blocked by 1H-[1,2,4] oxadiazolo [4,3-a] quinoxalin-1-one (ODQ; a guanylate cyclase inhibitor), KT5823 (a protein kinase G (PKG) inhibitor), and L-NAME (a non-selective nitric oxide synthase (NOS) inhibitor). In addition, zingerone stimulated cyclic guanosine monophosphate (cGMP) production in ICCs. Finally, pretreatment with PD98059 (a p42/44 mitogen-activated protein kinase (MAPK) inhibitor), SB203580 (a p38 MAPK inhibitor), and SP600125 (c-Jun N-terminal kinases (JNK)-specific inhibitor) blocked the zingerone-induced Pacemaker Potential inhibition. Conclusion These results suggest that zingerone concentration-dependently inhibits Pacemaker Potentials of ICCs via NO/cGMP-dependent ATP-sensitive K+ channels through MAPK-dependent pathways. Taken together, this study shows that zingerone may have the Potential for development as a GI regulation agent.
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Modulation of Pacemaker Potentials in Murine Small Intestinal Interstitial Cells of Cajal by Gamisoyo-San, a Traditional Chinese Herbal Medicine.
Digestion, 2018Co-Authors: Dy Kim, Jung Nam Kim, Joo Hyun Nam, Jong Rok Lee, Sang-chan Kim, Byung Joo KimAbstract:Background: The Gamisoyo-san (GSS) has been used for improving the gastrointestinal (GI) symptoms. The purpose of this study was to investigate the effects of GSS, a traditional Chinese herbal medicine, on the Pacemaker Potentials of mouse small intestinal interstitial cells of Cajal (ICCs). Methods: ICCs from the small intestines were dissociated and cultured. Whole-cell patch-clamp configuration was used to record Pacemaker Potentials and membrane currents. Results: GSS depolarized ICC Pacemaker Potentials in a dose-dependent manner. Pretreatment with 4-diphenylacetoxypiperidinium iodide completely inhibited GSS-induced Pacemaker Potential depolarizations. Intracellular GDP-β-S inhibited GSS-induced effects, and in the presence of U-73122, GSS-induced effects were inhibited. Also, GSS in the presence of a Ca 2+ -free solution or thapsigargin did not depolarize Pacemaker Potentials. However, in the presence of calphostin C, GSS slightly depolarized Pacemaker Potentials. Furthermore, GSS inhibited both transient receptor Potential melastatin7 and Ca 2+ -activated Cl – channel (anoctamin1) currents. Conclusion: GSS depolarized Pacemaker Potentials of ICCs via G protein and muscarinic M 3 receptor signaling pathways and through internal or external Ca 2+ -, phospholipase C-, and protein kinase C-dependent and transient receptor Potential melastatin 7-, and anoctamin 1-independent pathways. The study shows that GSS may regulate GI tract motility, suggesting that GSS could be a basis for developing novel prokinetic agents for treating GI motility dysfunctions.
Seok Choi - One of the best experts on this subject based on the ideXlab platform.
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Regulation of Intracellular Calcium by Endoplasmic Reticulum Proteins in Small Intestinal Interstitial Cells of Cajal.
Journal of neurogastroenterology and motility, 2018Co-Authors: Chan Guk Park, Chansik Hong, Han Yi Jiao, Jae Yeoul Jun, Hyun Jung Park, Seok ChoiAbstract:Background/Aims We investigated the role of representative endoplasmic reticulum proteins, stromal interaction molecule 1 (STIM1), and store-operated calcium entry-associated regulatory factor (SARAF) in Pacemaker activity in cultured interstitial cells of Cajal (ICCs) isolated from mouse small intestine. Methods The whole-cell patch clamp technique applied for intracellular calcium ions ([Ca2+]i) analysis with STIM1 or SARAF overexpressed cultured ICCs from mouse small intestine. Results In the current-clamping mode, cultured ICCs displayed spontaneous Pacemaker Potentials. External carbachol exposure produced tonic membrane depolarization in the current-clamp mode, which recovered within a few seconds into normal Pacemaker Potentials. In STIM1-overexpressing cultured ICCs Pacemaker Potential frequency was increased, and in SARAF-overexpressing ICCs Pacemaker Potential frequency was strongly inhibited. The application of gadolinium (a non-selective cation channel inhibitor) or a Ca2+-free solution to understand Orai channel involvement abolished the generation of Pacemaker Potentials. When recording intracellular Ca2+ concentration with Fluo 3-AM, STIM1-overexpressing ICCs showed an increased number of spontaneous intracellular Ca2+ oscillations. However, SARAF-overexpressing ICCs showed fewer spontaneous intracellular Ca2+ oscillations. Conclusion Endoplasmic reticulum proteins modulated the frequency of Pacemaker activity in ICCs, and levels of STIM1 and SARAF may determine slow wave patterns in the gastrointestinal tract.
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Effects of Ca2+-Activated Cl- Channel ANO1inhibitors on Pacemaker Activity in Interstitial Cells of Cajal
Karger Publishers, 2018Co-Authors: Seok Choi, Chansik Hong, Hyun goo Kang, Han yi Jiao, Dong hoon Shin, Jae yeoul JunAbstract:Background/Aims: Anoctamin1 (Ca2+-activated Cl- channel, ANO1) is a specific marker of the interstitial cells of Cajal (ICC) in the gastrointestinal tract, and are candidate proteins that can function as Pacemaker channels. Recently, novel selective ANO1 inhibitors were discovered and used to study Ca2+-activated Cl- channels. Therefore, to investigate whether ANO1 channels function as Pacemaker channels, selective ANO1 inhibitors were tested with respect to the Pacemaker Potentials in ICC. Methods: Whole-cell patch-clamp recording, RT-PCR, and intracellular Ca2+ ([Ca2+]i) imaging were performed in cultured ICC obtained from mice. Results: Though CaCCinh-A01 (5 µM), T16Ainh-A01 (5 µM), and MONNA (5 µM) (selective ANO1 inhibitors) blocked the generation of Pacemaker Potentials in colonic ICC, they did not do so in small intestinal ICC. Though nifulmic acid (10 µM) and DIDS (10 µM) (classical Ca2+-activated Cl- channel inhibitors) also had no effect in small intestinal ICC, they suppressed the generation of Pacemaker Potentials in colonic ICC. In addition, knockdown of ANO1 reduced the Pacemaker Potential frequency in colonic ICC alone. Though ANO1 inhibitors suppressed [Ca2+]i oscillations in colonic ICC, they did not do so in small intestinal ICC. T-type Ca2+ channels were expressed in the both the small intestinal and colonic ICC, but mibefradil (5 µM) and NiCl2 (30 µM) (T-type Ca2+ channel inhibitors) inhibited the generation of Pacemaker Potentials in colonic ICC alone. Conclusion: These results indicate that though ANO1 and T-type Ca2+ channels participate in generating Pacemaker Potentials in colonic ICC, they do not do so in small intestinal ICC. Therefore, the mechanisms underlying pacemaking in ICC might be different in the small intestine and the colon
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ATP-sensitive K+ channels maintain resting membrane Potential in interstitial cells of Cajal from the mouse colon.
European journal of pharmacology, 2017Co-Authors: Chansik Hong, Seok Choi, Chan Guk Park, Man Woo Kim, Hyun Goo Kang, Han Yi Jiao, Jae Yeoul JunAbstract:To investigate the role of ATP-sensitive K+(KATP) channels on Pacemaker activity in interstitial cells of Cajal (ICC), whole-cell patch clamping, RT-PCR, and intracellular Ca2+([Ca2+]i) imaging were performed in cultured colonic ICC. Pinacidil (a K+ channel opener) hyperpolarized the membrane and inhibited the generation of Pacemaker Potential, and this effect was reversed by glibenclamide (a KATP channel blocker). RT-PCR showed that Kir 6.1 and SUR2B were expressed in Ano-1 positive colonic ICC. Glibenclamide depolarized the membrane and increased Pacemaker Potential frequency. However, 5-hydroxydecanoic acid (a mitochondrial KATP channel blocker) had no effects on Pacemaker Potentials. Phorbol 12-myristate 13-acetate (PMA; a protein kinase C activator) blocked the pinacidil-induced effects, and PMA alone depolarized the membrane and increased Pacemaker Potential frequency. Cell-permeable 8-bromo-cyclic AMP also increased Pacemaker Potential frequency. Recordings of spontaneous intracellular Ca2+([Ca2+]i) oscillations showed that glibenclamide increased the frequency of [Ca2+]i oscillations. In small intestinal ICC, glibenclamide alone did not alter the generation of Pacemaker Potentials, and Kir 6.2 and SUR2B were expressed in Ano-1 positive ICC. Therefore, KATP channels in colonic ICC are activated in resting state and play an important role in maintaining resting membrane Potential.
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Regulation of the Pacemaker Activity of Colonic Interstitial Cells of Cajal by Protease-Activated Receptors: Involvement of Hyperpolarization-Activated Cyclic Nucleotide Channels
Pharmacology, 2016Co-Authors: Dong Hoon Shin, Seok Choi, Chan Guk Park, Man Woo Kim, Dong Chuan Zuo, Young Dae Kim, Jun Lee, Ju Yeon Cho, Jae Yeoul JunAbstract:Background and Purpose: The exact mechanism of protease-activated receptors (PARs) on Pacemaker activity of interstitial cells of Cajal (ICCs) has not been reported. We investigated the effects on Pacemaker activity by the activation of PARs and its signal mechanisms in colonic ICCs. Methods: The whole-cell patch-clamp technique, RT-PCR and Ca2+ imaging were used in cultured ICCs from mouse colon. Results: PAR-1 and PAR-2 were expressed in Ano-1 positive ICCs. TFLLR-NH2 (a PAR-1 agonist) and trypsin (a PAR-2 agonist) depolarized the membrane and increased the Pacemaker Potential frequency. U-73122 (a phospholipase C (PLC) inhibitor) and thapsigargin (a Ca2+ ATPase inhibitor) suppressed the TFLLR-NH2- and trypsin-induced effects on Pacemaker Potential. TFLLR-NH2 and trypsin also increased intracellular Ca2+ ([Ca2+]i) intensity with increasing of Ca2+ oscillations. Genistein (a tyrosine kinase inhibitor), SP600125 (a JNK inhibitor), CsCl, ZD7288, clonidine (hyperpolarization-activated cyclic nucleotide (HCN) channel blockers), SQ-22536 and dideoxyadenosine (adenylate cyclase inhibitors) suppressed the increased Pacemaker Potential frequency without effects on depolarization of the membrane induced by TFLLR-NH2 and trypsin. Conclusion: These results suggest that activation of PAR-1 and PAR-2 modulates the Pacemaker activity of colonic ICCs through the PLC-dependent [Ca2+]i release pathway. The increased Pacemaker Potential frequency by PAR-1 and PAR-2 was also dependent on tyrosine kinase, JNK, and HCN activation.
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Pituitary Adenylate Cyclase-activating Polypeptide Inhibits Pacemaker Activity of Colonic Interstitial Cells of Cajal
The Korean journal of physiology & pharmacology : official journal of the Korean Physiological Society and the Korean Society of Pharmacology, 2015Co-Authors: Keun Hong Kee, Seok Choi, Jae Yeoul Jun, Dong Hoon Shin, Han Seong Jeong, Seok Won Kim, Youin Bae, Jong Seong ParkAbstract:This study aimed to investigate the effect of pituitary adenylate cyclase-activating peptide (PACAP) on the Pacemaker activity of interstitial cells of Cajal (ICC) in mouse colon and to identify the underlying mechanisms of PACAP action. Spontaneous Pacemaker activity of colonic ICC and the effects of PACAP were studied using electrophysiological recordings. Exogenously applied PACAP induced hyperpolarization of the cell membrane and inhibited Pacemaker frequency in a dose-dependent manner (from 0.1 nM to 100 nM). To investigate cyclic AMP (cAMP) involvement in the effects of PACAP on ICC, SQ-22536 (an inhibitor of adenylate cyclase) and cell-permeable 8-bromo-cAMP were used. SQ-22536 decreased the frequency of Pacemaker Potentials, and cell-permeable 8-bromo-cAMP increased the frequency of Pacemaker Potentials. The effects of SQ-22536 on Pacemaker Potential frequency and membrane hyperpolarization were rescued by co-treatment with glibenclamide (an ATP-sensitive K(+) channel blocker). However, neither N (G)-nitro-L-arginine methyl ester (L-NAME, a competitive inhibitor of NO synthase) nor 1H-[1,2,4]oxadiazolo[4,3-α]quinoxalin-1-one (ODQ, an inhibitor of guanylate cyclase) had any effect on PACAP-induced activity. In conclusion, this study describes the effects of PACAP on ICC in the mouse colon. PACAP inhibited the Pacemaker activity of ICC by acting through ATP-sensitive K(+) channels. These results provide evidence of a physiological role for PACAP in regulating gastrointestinal (GI) motility through the modulation of ICC activity.
Chan Guk Park - One of the best experts on this subject based on the ideXlab platform.
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Regulation of Intracellular Calcium by Endoplasmic Reticulum Proteins in Small Intestinal Interstitial Cells of Cajal.
Journal of neurogastroenterology and motility, 2018Co-Authors: Chan Guk Park, Chansik Hong, Han Yi Jiao, Jae Yeoul Jun, Hyun Jung Park, Seok ChoiAbstract:Background/Aims We investigated the role of representative endoplasmic reticulum proteins, stromal interaction molecule 1 (STIM1), and store-operated calcium entry-associated regulatory factor (SARAF) in Pacemaker activity in cultured interstitial cells of Cajal (ICCs) isolated from mouse small intestine. Methods The whole-cell patch clamp technique applied for intracellular calcium ions ([Ca2+]i) analysis with STIM1 or SARAF overexpressed cultured ICCs from mouse small intestine. Results In the current-clamping mode, cultured ICCs displayed spontaneous Pacemaker Potentials. External carbachol exposure produced tonic membrane depolarization in the current-clamp mode, which recovered within a few seconds into normal Pacemaker Potentials. In STIM1-overexpressing cultured ICCs Pacemaker Potential frequency was increased, and in SARAF-overexpressing ICCs Pacemaker Potential frequency was strongly inhibited. The application of gadolinium (a non-selective cation channel inhibitor) or a Ca2+-free solution to understand Orai channel involvement abolished the generation of Pacemaker Potentials. When recording intracellular Ca2+ concentration with Fluo 3-AM, STIM1-overexpressing ICCs showed an increased number of spontaneous intracellular Ca2+ oscillations. However, SARAF-overexpressing ICCs showed fewer spontaneous intracellular Ca2+ oscillations. Conclusion Endoplasmic reticulum proteins modulated the frequency of Pacemaker activity in ICCs, and levels of STIM1 and SARAF may determine slow wave patterns in the gastrointestinal tract.
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ATP-sensitive K+ channels maintain resting membrane Potential in interstitial cells of Cajal from the mouse colon.
European journal of pharmacology, 2017Co-Authors: Chansik Hong, Seok Choi, Chan Guk Park, Man Woo Kim, Hyun Goo Kang, Han Yi Jiao, Jae Yeoul JunAbstract:To investigate the role of ATP-sensitive K+(KATP) channels on Pacemaker activity in interstitial cells of Cajal (ICC), whole-cell patch clamping, RT-PCR, and intracellular Ca2+([Ca2+]i) imaging were performed in cultured colonic ICC. Pinacidil (a K+ channel opener) hyperpolarized the membrane and inhibited the generation of Pacemaker Potential, and this effect was reversed by glibenclamide (a KATP channel blocker). RT-PCR showed that Kir 6.1 and SUR2B were expressed in Ano-1 positive colonic ICC. Glibenclamide depolarized the membrane and increased Pacemaker Potential frequency. However, 5-hydroxydecanoic acid (a mitochondrial KATP channel blocker) had no effects on Pacemaker Potentials. Phorbol 12-myristate 13-acetate (PMA; a protein kinase C activator) blocked the pinacidil-induced effects, and PMA alone depolarized the membrane and increased Pacemaker Potential frequency. Cell-permeable 8-bromo-cyclic AMP also increased Pacemaker Potential frequency. Recordings of spontaneous intracellular Ca2+([Ca2+]i) oscillations showed that glibenclamide increased the frequency of [Ca2+]i oscillations. In small intestinal ICC, glibenclamide alone did not alter the generation of Pacemaker Potentials, and Kir 6.2 and SUR2B were expressed in Ano-1 positive ICC. Therefore, KATP channels in colonic ICC are activated in resting state and play an important role in maintaining resting membrane Potential.
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Regulation of the Pacemaker Activity of Colonic Interstitial Cells of Cajal by Protease-Activated Receptors: Involvement of Hyperpolarization-Activated Cyclic Nucleotide Channels
Pharmacology, 2016Co-Authors: Dong Hoon Shin, Seok Choi, Chan Guk Park, Man Woo Kim, Dong Chuan Zuo, Young Dae Kim, Jun Lee, Ju Yeon Cho, Jae Yeoul JunAbstract:Background and Purpose: The exact mechanism of protease-activated receptors (PARs) on Pacemaker activity of interstitial cells of Cajal (ICCs) has not been reported. We investigated the effects on Pacemaker activity by the activation of PARs and its signal mechanisms in colonic ICCs. Methods: The whole-cell patch-clamp technique, RT-PCR and Ca2+ imaging were used in cultured ICCs from mouse colon. Results: PAR-1 and PAR-2 were expressed in Ano-1 positive ICCs. TFLLR-NH2 (a PAR-1 agonist) and trypsin (a PAR-2 agonist) depolarized the membrane and increased the Pacemaker Potential frequency. U-73122 (a phospholipase C (PLC) inhibitor) and thapsigargin (a Ca2+ ATPase inhibitor) suppressed the TFLLR-NH2- and trypsin-induced effects on Pacemaker Potential. TFLLR-NH2 and trypsin also increased intracellular Ca2+ ([Ca2+]i) intensity with increasing of Ca2+ oscillations. Genistein (a tyrosine kinase inhibitor), SP600125 (a JNK inhibitor), CsCl, ZD7288, clonidine (hyperpolarization-activated cyclic nucleotide (HCN) channel blockers), SQ-22536 and dideoxyadenosine (adenylate cyclase inhibitors) suppressed the increased Pacemaker Potential frequency without effects on depolarization of the membrane induced by TFLLR-NH2 and trypsin. Conclusion: These results suggest that activation of PAR-1 and PAR-2 modulates the Pacemaker activity of colonic ICCs through the PLC-dependent [Ca2+]i release pathway. The increased Pacemaker Potential frequency by PAR-1 and PAR-2 was also dependent on tyrosine kinase, JNK, and HCN activation.
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Basal cGMP regulates the resting Pacemaker Potential frequency of cultured mouse colonic interstitial cells of Cajal
Naunyn-Schmiedeberg's Archives of Pharmacology, 2014Co-Authors: Pawan Kumar Shahi, Seok Choi, Yu Jin Jeong, Chan Guk Park, Insuk SoAbstract:Cyclic guanosine 3′,5′-monophosphate (cGMP) inhibited the generation of Pacemaker activity in interstitial cells of Cajal (ICCs) from the small intestine. However, cGMP role on Pacemaker activity in colonic ICCs has not been reported yet. Thus, we investigated the role of cGMP in Pacemaker activity regulation by colonic ICCs. We performed a whole-cell patch-clamp and Ca^2+ imaging in cultured ICCs from mouse colon. 1H-[1,2,4]Oxadiazolo[4,3-a]quinoxalin-1-one (ODQ, an inhibitor of guanylate cyclase) increased the Pacemaker Potential frequency, whereas zaprinast (an inhibitor of phosphodiesterase) and cell-permeable 8-bromo-cGMP decreased the Pacemaker Potential frequency. KT-5823 (an inhibitor of protein kinase G [PKG]) did not affect the Pacemaker Potential. L-N^G-nitroarginine methyl ester (L-NAME, an inhibitor of nitric oxide [NO] synthase) increased the Pacemaker Potential frequency, whereas (±)- S -nitroso- N -acetylpenicillamine (SNAP, a NO donor) decreased the Pacemaker Potential frequency. Glibenclamide (an ATP-sensitive K^+ channel blocker) did not block the effects of cell-permeable 8-bromo-cGMP and SNAP. Recordings of spontaneous intracellular Ca^2+ ([Ca^2+]_i) oscillations revealed that ODQ and L-NAME increased [Ca^2+]_i oscillations. In contrast, zaprinast, 8-bromo cGMP, and SNAP decreased the [Ca^2+]_i oscillations. Basal cGMP levels regulate the resting Pacemaker Potential frequency by the alteration on Ca^2+ release via a PKG-independent pathway. Additionally, the endogenous release of NO seems to be responsible maintaining basal cGMP levels in colonic ICCs.
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Inhibition of Pacemaker currents by nitric oxide via activation of ATP-sensitive K^+ channels in cultured interstitial cells of Cajal from the mouse small intestine
Naunyn-Schmiedeberg's Archives of Pharmacology, 2007Co-Authors: Chan Guk Park, Seok Choi, Cheol Ho Yeum, Shankar Prasad Parajuli, Jong Seong Park, Han Seong Jeong, Insuk SoAbstract:We investigated the role of nitric oxide (NO) in Pacemaker activity and signal mechanisms in cultured interstitial cells of Cajal (ICC) of the mouse small intestine using whole cell patch-clamp techniques at 30°C. ICC generated Pacemaker Potential in the current clamp mode and Pacemaker currents at a holding Potential of –70 mV. (±)-S-nitroso- N -acetylpenicillamine (SNAP; a NO donor) produced membrane hyperpolarization and inhibited the amplitude and frequency of the Pacemaker currents, and increased resting currents in the outward direction. These effects were blocked by the use of glibenclamide (an ATP-sensitive K^+ channel blocker), but not by the use of 5-hydroxydecanoic acid (a mitochondrial ATP-sensitive K^+ channel blocker). Pretreatment with ODQ (a guanylate cyclase inhibitor) almost blocked the NO-induced effects. The use of cell-permeable 8-bromo-cyclic GMP also mimicked the action of SNAP. However, the use of KT-5823 (a protein kinase G inhibitor) did not block the NO-induced effects. Spontaneous [Ca^2+]_i oscillations in ICC were inhibited by the treatment of SNAP, as seen in recordings of intracellular Ca^2+ ([Ca^2+]_i). These results suggest that NO inhibits Pacemaker activity by the activation of ATP-sensitive K^+ channels via a cyclic GMP dependent mechanism in ICC, and the activation of ATP-sensitive K^+ channels mediates the inhibition of spontaneous [Ca^2+]_i oscillations.
Matthew K. Lancaster - One of the best experts on this subject based on the ideXlab platform.
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requirement of neuronal and cardiac type sodium channels for murine sinoatrial node pacemaking
The Journal of Physiology, 2004Co-Authors: Sandra A Jones, Sebastian K G Maier, Halina Dobrzynski, Matthew K. Lancaster, Simon S M Fung, P Camelliti, Denis Noble, Mark R. BoyettAbstract:The majority of Na+ channels in the heart are composed of the tetrodotoxin (TTX)-resistant (KD, 2–6 μm) Nav1.5 isoform; however, recently it has been shown that TTX-sensitive (KD, 1–10 nm) neuronal Na+ channel isoforms (Nav1.1, Nav1.3 and Nav1.6) are also present and functionally important in the myocytes of the ventricles and the sinoatrial (SA) node. In the present study, in mouse SA node Pacemaker cells, we investigated Na+ currents under physiological conditions and the expression of cardiac and neuronal Na+ channel isoforms. We identified two distinct Na+ current components, TTX resistant and TTX sensitive. At 37°C, TTX-resistant iNa and TTX-sensitive iNa started to activate at ∼−70 and ∼−60 mV, and peaked at −30 and −10 mV, with a current density of 22 ± 3 and 18 ± 1 pA pF−1, respectively. TTX-sensitive iNa inactivated at more positive Potentials as compared to TTX-resistant iNa. Using action Potential clamp, TTX-sensitive iNa was observed to activate late during the Pacemaker Potential. Using immunocytochemistry and confocal microscopy, different distributions of the TTX-resistant cardiac isoform, Nav1.5, and the TTX-sensitive neuronal isoform, Nav1.1, were observed: Nav1.5 was absent from the centre of the SA node, but present in the periphery of the SA node, whereas Nav1.1 was present throughout the SA node. Nanomolar concentrations (10 or 100 nm) of TTX, which block TTX-sensitive iNa, slowed pacemaking in both intact SA node preparations and isolated SA node cells without a significant effect on SA node conduction. In contrast, micromolar concentrations (1–30 μm) of TTX, which block TTX-resistant iNa as well as TTX-sensitive iNa, slowed both pacemaking and SA node conduction. It is concluded that two Na+ channel isoforms are important for the functioning of the SA node: neuronal (putative Nav1.1) and cardiac Nav1.5 isoforms are involved in pacemaking, although the cardiac Nav1.5 isoform alone is involved in the propagation of the action Potential from the SA node to the surrounding atrial muscle.
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Sarcoplasmic Reticulum Ca2+ Release Is Not a Dominating Factor in Sinoatrial Node Pacemaker Activity
Circulation Research, 2003Co-Authors: Haruo Honjo, S. A. Jones, Matthew K. Lancaster, Shin Inada, Mitsuru Yamamoto, Ryoko Niwa, Nitaro Shibata, Kazuyuki Mitsui, T. Horiuchi, K. KamiyaAbstract:Recent work on isolated sinoatrial node cells from rabbit has suggested that sarcoplasmic reticulum Ca 2+ release plays a dominant role in the Pacemaker Potential, and ryanodine at a high concentration (30 μmol/L blocks sarcoplasmic reticulum Ca 2+ release) abolishes pacemaking and at a lower concentration abolishes the chronotropic effect of β-adrenergic stimulation. The aim of the present study was to test this hypothesis in the intact sinoatrial node of the rabbit. Spontaneous activity and the pattern of activation were recorded using a grid of 120 pairs of extracellular electrodes. Ryanodine 30 μmol/L did not abolish spontaneous activity or shift the position of the leading Pacemaker site, although it slowed the spontaneous rate by 18.9±2.5% (n=6). After ryanodine treatment, β-adrenergic stimulation still resulted in a substantial chronotropic effect (0.3 μmol/L isoproterenol increased spontaneous rate by 52.6±10.5%, n=5). In isolated sinoatrial node cells from rabbit, 30 μmol/L ryanodine slowed spontaneous rate by 21.5±2.6% (n=13). It is concluded that sarcoplasmic reticulum Ca 2+ release does not play a dominating role in pacemaking in the sinoatrial node. The full text of this article is available at http://www.circresaha.org.
Denis Noble - One of the best experts on this subject based on the ideXlab platform.
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requirement of neuronal and cardiac type sodium channels for murine sinoatrial node pacemaking
The Journal of Physiology, 2004Co-Authors: Sandra A Jones, Sebastian K G Maier, Halina Dobrzynski, Matthew K. Lancaster, Simon S M Fung, P Camelliti, Denis Noble, Mark R. BoyettAbstract:The majority of Na+ channels in the heart are composed of the tetrodotoxin (TTX)-resistant (KD, 2–6 μm) Nav1.5 isoform; however, recently it has been shown that TTX-sensitive (KD, 1–10 nm) neuronal Na+ channel isoforms (Nav1.1, Nav1.3 and Nav1.6) are also present and functionally important in the myocytes of the ventricles and the sinoatrial (SA) node. In the present study, in mouse SA node Pacemaker cells, we investigated Na+ currents under physiological conditions and the expression of cardiac and neuronal Na+ channel isoforms. We identified two distinct Na+ current components, TTX resistant and TTX sensitive. At 37°C, TTX-resistant iNa and TTX-sensitive iNa started to activate at ∼−70 and ∼−60 mV, and peaked at −30 and −10 mV, with a current density of 22 ± 3 and 18 ± 1 pA pF−1, respectively. TTX-sensitive iNa inactivated at more positive Potentials as compared to TTX-resistant iNa. Using action Potential clamp, TTX-sensitive iNa was observed to activate late during the Pacemaker Potential. Using immunocytochemistry and confocal microscopy, different distributions of the TTX-resistant cardiac isoform, Nav1.5, and the TTX-sensitive neuronal isoform, Nav1.1, were observed: Nav1.5 was absent from the centre of the SA node, but present in the periphery of the SA node, whereas Nav1.1 was present throughout the SA node. Nanomolar concentrations (10 or 100 nm) of TTX, which block TTX-sensitive iNa, slowed pacemaking in both intact SA node preparations and isolated SA node cells without a significant effect on SA node conduction. In contrast, micromolar concentrations (1–30 μm) of TTX, which block TTX-resistant iNa as well as TTX-sensitive iNa, slowed both pacemaking and SA node conduction. It is concluded that two Na+ channel isoforms are important for the functioning of the SA node: neuronal (putative Nav1.1) and cardiac Nav1.5 isoforms are involved in pacemaking, although the cardiac Nav1.5 isoform alone is involved in the propagation of the action Potential from the SA node to the surrounding atrial muscle.
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effect of isoprenaline carbachol and cs on na activity and Pacemaker Potential in rabbit sa node cells
American Journal of Physiology-heart and Circulatory Physiology, 1999Co-Authors: Ho S Choi, Denis Noble, Dai Y Wang, Chin O LeeAbstract:Effects of isoprenaline, carbachol, and Cs+on intracellular Na+ activity ( a Na i ) and spontaneous action Potentials were studied in multicellular and single cell preparations isolated from rabbit...
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Simulating cardiac sinus and atrial network dynamics on the Connection Machine
Physica D: Nonlinear Phenomena, 1993Co-Authors: Raimond L. Winslow, A. Kimball, Anthony Varghese, Denis NobleAbstract:Abstract Computational methods for simulating biophysically detailed, large-scale models of mammalian cardiac sinus and atrial networks on the massively parallel Connection Machine CM-2, and techniques for visualization of simulation data, are presented. Individual cells are modeled using the formulations of Noble et al. Models incorporate properties of voltage-dependent membrane currents, ion pumps and exchangers, and internal calcium sequestering and release mechanisms. Network models are used to investigate factors determining the site of generation and direction of propagation of the Pacemaker Potential. Models of the isolated sinus node are used to show that very few gap junction channels are required to support frequency entrainment. When cell membrane properties in the isolated sinus node models are modified to reproduce regional differences in oscillation properties, as described by the data of Kodama and Boyett, an excitatory wave is generated in the node periphery which propagates towards the node center. This agrees with activation patterns measured in the isolated sinus node by Kirchoff. When the model sinus node is surrounded by a region of atrial cells, the site of Pacemaker Potential generation is shifted away from the periphery towards the node center. This is in agreement with activation patterns measured by Kirchoff in the intact sinus node of the rabbit heart, and demonstrates the importance of sinus node boundary conditions on shaping the site of generation and direction of propagation of the Pacemaker Potential.
