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The role of K⁺ conductances in regulating membrane excitability in human gastric corpus smooth muscle.

Lee JY, Ko EJ, Ahn KD, Kim S, Rhee PL - Am. J. Physiol. Gastrointest. Liver Physiol. (2015)

Bottom Line: Tetraethylammonium and charybdotoxin did not affect the RMP, suggesting that BK channels are not involved in regulating RMP.Apamin, a selective small conductance Ca(2+)-activated K(+) channel (SK) blocker, did not show a significant effect on the membrane excitability. 4-Aminopyridine, a Kv channel blocker, caused depolarization and increased the duration of slow wave potentials. 4-Aminopyridine also inhibited a delayed rectifying K(+) current in isolated smooth muscle cells.Glibenclamide, an ATP-sensitive K(+) channel (KATP) blocker, did not induce depolarization, but nicorandil, a KATP opener, hyperpolarized HGCS, suggesting that KATP are expressed but not basally activated.

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Affiliation: Samsung Biomedical Research Institute and.

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Effect of 4-aminopyridine (4-AP) on the slow wave potential in HGCS. A: a representative trace showed that low (1 mM) and high (5 mM) concentration of 4-AP depolarized HGCS with decreased slow wave amplitude and frequency. B and C: expanded time scale from A in control (B) and 4-AP (5 mM) presence (C), respectively. D–F: summarized data showed significant changes in the resting membrane potential (RMP, D), slow wave amplitude (E), and half duration of slow wave potentials (F) from 5 samples in each concentration of 4-AP. *P < 0.05; **P < 0.01.
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Figure 2: Effect of 4-aminopyridine (4-AP) on the slow wave potential in HGCS. A: a representative trace showed that low (1 mM) and high (5 mM) concentration of 4-AP depolarized HGCS with decreased slow wave amplitude and frequency. B and C: expanded time scale from A in control (B) and 4-AP (5 mM) presence (C), respectively. D–F: summarized data showed significant changes in the resting membrane potential (RMP, D), slow wave amplitude (E), and half duration of slow wave potentials (F) from 5 samples in each concentration of 4-AP. *P < 0.05; **P < 0.01.

Mentions: To examine the role of Kv channels on RMP, we tested the effects of 4-AP on electrical events in HGCS. 4-AP (1 mM) induced depolarization but not significantly (e.g., from −68 ± 4 mV to −64 ± 4 mV, P = 0.09, n = 5). Higher concentration of 4-AP (5 mM) depolarized HGCS, significantly (−56 ± 4 mV, P < 0.05 compared with control, n = 5, Fig. 2, A–D). 4-AP significantly decreased the amplitude of SWP (Fig. 2, A–C and E) and increased the half-duration of SWP from 0.12 ± 0.01 to 0.25 ± 0.02 s (P < 0.01, n = 5). These data suggest that 4-AP-sensitive Kv channels are involved in regulating RMP and membrane repolarization in HGCS.


The role of K⁺ conductances in regulating membrane excitability in human gastric corpus smooth muscle.

Lee JY, Ko EJ, Ahn KD, Kim S, Rhee PL - Am. J. Physiol. Gastrointest. Liver Physiol. (2015)

Effect of 4-aminopyridine (4-AP) on the slow wave potential in HGCS. A: a representative trace showed that low (1 mM) and high (5 mM) concentration of 4-AP depolarized HGCS with decreased slow wave amplitude and frequency. B and C: expanded time scale from A in control (B) and 4-AP (5 mM) presence (C), respectively. D–F: summarized data showed significant changes in the resting membrane potential (RMP, D), slow wave amplitude (E), and half duration of slow wave potentials (F) from 5 samples in each concentration of 4-AP. *P < 0.05; **P < 0.01.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4385896&req=5

Figure 2: Effect of 4-aminopyridine (4-AP) on the slow wave potential in HGCS. A: a representative trace showed that low (1 mM) and high (5 mM) concentration of 4-AP depolarized HGCS with decreased slow wave amplitude and frequency. B and C: expanded time scale from A in control (B) and 4-AP (5 mM) presence (C), respectively. D–F: summarized data showed significant changes in the resting membrane potential (RMP, D), slow wave amplitude (E), and half duration of slow wave potentials (F) from 5 samples in each concentration of 4-AP. *P < 0.05; **P < 0.01.
Mentions: To examine the role of Kv channels on RMP, we tested the effects of 4-AP on electrical events in HGCS. 4-AP (1 mM) induced depolarization but not significantly (e.g., from −68 ± 4 mV to −64 ± 4 mV, P = 0.09, n = 5). Higher concentration of 4-AP (5 mM) depolarized HGCS, significantly (−56 ± 4 mV, P < 0.05 compared with control, n = 5, Fig. 2, A–D). 4-AP significantly decreased the amplitude of SWP (Fig. 2, A–C and E) and increased the half-duration of SWP from 0.12 ± 0.01 to 0.25 ± 0.02 s (P < 0.01, n = 5). These data suggest that 4-AP-sensitive Kv channels are involved in regulating RMP and membrane repolarization in HGCS.

Bottom Line: Tetraethylammonium and charybdotoxin did not affect the RMP, suggesting that BK channels are not involved in regulating RMP.Apamin, a selective small conductance Ca(2+)-activated K(+) channel (SK) blocker, did not show a significant effect on the membrane excitability. 4-Aminopyridine, a Kv channel blocker, caused depolarization and increased the duration of slow wave potentials. 4-Aminopyridine also inhibited a delayed rectifying K(+) current in isolated smooth muscle cells.Glibenclamide, an ATP-sensitive K(+) channel (KATP) blocker, did not induce depolarization, but nicorandil, a KATP opener, hyperpolarized HGCS, suggesting that KATP are expressed but not basally activated.

View Article: PubMed Central - PubMed

Affiliation: Samsung Biomedical Research Institute and.

Show MeSH
Related in: MedlinePlus