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The possible roles of hyperpolarization-activated cyclic nucleotide channels in regulating pacemaker activity in colonic interstitial cells of Cajal.

Shahi PK, Choi S, Zuo DC, Kim MY, Park CG, Kim YD, Lee J, Park KJ, So I, Jun JY - J. Gastroenterol. (2013)

Bottom Line: CsCl, ZD7288, zatebradine, clonidine (HCN channel blockers), and genistein (a tyrosine kinase inhibitor) suppressed the pacemaker activity.In recordings of spontaneous intracellular Ca(2+) [Ca(2+)]i oscillations, rolipram and 8-bromo-cAMP increased [Ca(2+)]i oscillations, whereas SQ-22536, CsCl, ZD7288, and genistein decreased [Ca(2+)]i oscillations.HCN channels in colonic ICCs are tonically activated by basal cAMP production and participate in regulation of pacemaking activity.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology, College of Medicine, Chosun University, Sesuk-dong, Dong-gu, Gwangju, 501-759, Korea.

ABSTRACT

Background: Hyperpolarization-activated cyclic nucleotide (HCN) channels are pacemaker channels that regulate heart rate and neuronal rhythm in spontaneously active cardiac and neuronal cells. Interstitial cells of Cajal (ICCs) are also spontaneously active pacemaker cells in the gastrointestinal tract. Here, we investigated the existence of HCN channel and its role on pacemaker activity in colonic ICCs.

Methods: We performed whole-cell patch clamp, RT-PCR, and Ca(2+)-imaging in cultured ICCs from mouse mid colon.

Results: SQ-22536 and dideoxyadenosine (adenylate cyclase inhibitors) decreased the frequency of pacemaker potentials, whereas both rolipram (cAMP-specific phosphodiesterase inhibitor) and cell-permeable 8-bromo-cAMP increased the frequency of pacemaker potentials. CsCl, ZD7288, zatebradine, clonidine (HCN channel blockers), and genistein (a tyrosine kinase inhibitor) suppressed the pacemaker activity. RT-PCR revealed expression of HCN1 and HCN3 channels in c-kit and Ano1 positive colonic ICCs. In recordings of spontaneous intracellular Ca(2+) [Ca(2+)]i oscillations, rolipram and 8-bromo-cAMP increased [Ca(2+)]i oscillations, whereas SQ-22536, CsCl, ZD7288, and genistein decreased [Ca(2+)]i oscillations.

Conclusions: HCN channels in colonic ICCs are tonically activated by basal cAMP production and participate in regulation of pacemaking activity.

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Related in: MedlinePlus

RT-PCR detection and expression of hyperpolarization-activated cyclic nucleotide (HCN) channels protein in cultured ICCs of mouse mid colon. Mouse heart and HEK-293 cells were used as positive and negative controls (a). Four HCN channel subtypes (HCN1–HCN4) were amplified in whole mounted cultured cells from mouse colon (b). However, only the HCN1 and HCN3 channel subtypes were amplified in c-kit and Ano1 positive cultured colonic ICCs (c)
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Fig5: RT-PCR detection and expression of hyperpolarization-activated cyclic nucleotide (HCN) channels protein in cultured ICCs of mouse mid colon. Mouse heart and HEK-293 cells were used as positive and negative controls (a). Four HCN channel subtypes (HCN1–HCN4) were amplified in whole mounted cultured cells from mouse colon (b). However, only the HCN1 and HCN3 channel subtypes were amplified in c-kit and Ano1 positive cultured colonic ICCs (c)

Mentions: To support the above functional data, we performed RT-PCR to detect expression of HCN channels. There are four subtypes of the HCN channels: HCN1–HCN4. In this study, we used mouse heart and HEK-293 cells as positive and negative controls for HCN channels (n = 4; Fig. 5a). RT-PCR analysis revealed the mRNA transcripts for all four HCN channel subtypes in whole mount cultured colonic cells (n = 12; Fig. 5b). However, the mRNA transcripts for only HCN1 and HCN3 channel were detected in cultured c-kit and Ano1 positive isolated ICCs (n = 14; Fig. 5c).Fig. 5


The possible roles of hyperpolarization-activated cyclic nucleotide channels in regulating pacemaker activity in colonic interstitial cells of Cajal.

Shahi PK, Choi S, Zuo DC, Kim MY, Park CG, Kim YD, Lee J, Park KJ, So I, Jun JY - J. Gastroenterol. (2013)

RT-PCR detection and expression of hyperpolarization-activated cyclic nucleotide (HCN) channels protein in cultured ICCs of mouse mid colon. Mouse heart and HEK-293 cells were used as positive and negative controls (a). Four HCN channel subtypes (HCN1–HCN4) were amplified in whole mounted cultured cells from mouse colon (b). However, only the HCN1 and HCN3 channel subtypes were amplified in c-kit and Ano1 positive cultured colonic ICCs (c)
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Related In: Results  -  Collection

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Fig5: RT-PCR detection and expression of hyperpolarization-activated cyclic nucleotide (HCN) channels protein in cultured ICCs of mouse mid colon. Mouse heart and HEK-293 cells were used as positive and negative controls (a). Four HCN channel subtypes (HCN1–HCN4) were amplified in whole mounted cultured cells from mouse colon (b). However, only the HCN1 and HCN3 channel subtypes were amplified in c-kit and Ano1 positive cultured colonic ICCs (c)
Mentions: To support the above functional data, we performed RT-PCR to detect expression of HCN channels. There are four subtypes of the HCN channels: HCN1–HCN4. In this study, we used mouse heart and HEK-293 cells as positive and negative controls for HCN channels (n = 4; Fig. 5a). RT-PCR analysis revealed the mRNA transcripts for all four HCN channel subtypes in whole mount cultured colonic cells (n = 12; Fig. 5b). However, the mRNA transcripts for only HCN1 and HCN3 channel were detected in cultured c-kit and Ano1 positive isolated ICCs (n = 14; Fig. 5c).Fig. 5

Bottom Line: CsCl, ZD7288, zatebradine, clonidine (HCN channel blockers), and genistein (a tyrosine kinase inhibitor) suppressed the pacemaker activity.In recordings of spontaneous intracellular Ca(2+) [Ca(2+)]i oscillations, rolipram and 8-bromo-cAMP increased [Ca(2+)]i oscillations, whereas SQ-22536, CsCl, ZD7288, and genistein decreased [Ca(2+)]i oscillations.HCN channels in colonic ICCs are tonically activated by basal cAMP production and participate in regulation of pacemaking activity.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology, College of Medicine, Chosun University, Sesuk-dong, Dong-gu, Gwangju, 501-759, Korea.

ABSTRACT

Background: Hyperpolarization-activated cyclic nucleotide (HCN) channels are pacemaker channels that regulate heart rate and neuronal rhythm in spontaneously active cardiac and neuronal cells. Interstitial cells of Cajal (ICCs) are also spontaneously active pacemaker cells in the gastrointestinal tract. Here, we investigated the existence of HCN channel and its role on pacemaker activity in colonic ICCs.

Methods: We performed whole-cell patch clamp, RT-PCR, and Ca(2+)-imaging in cultured ICCs from mouse mid colon.

Results: SQ-22536 and dideoxyadenosine (adenylate cyclase inhibitors) decreased the frequency of pacemaker potentials, whereas both rolipram (cAMP-specific phosphodiesterase inhibitor) and cell-permeable 8-bromo-cAMP increased the frequency of pacemaker potentials. CsCl, ZD7288, zatebradine, clonidine (HCN channel blockers), and genistein (a tyrosine kinase inhibitor) suppressed the pacemaker activity. RT-PCR revealed expression of HCN1 and HCN3 channels in c-kit and Ano1 positive colonic ICCs. In recordings of spontaneous intracellular Ca(2+) [Ca(2+)]i oscillations, rolipram and 8-bromo-cAMP increased [Ca(2+)]i oscillations, whereas SQ-22536, CsCl, ZD7288, and genistein decreased [Ca(2+)]i oscillations.

Conclusions: HCN channels in colonic ICCs are tonically activated by basal cAMP production and participate in regulation of pacemaking activity.

Show MeSH
Related in: MedlinePlus