The role of K⁺ conductances in regulating membrane excitability in human gastric corpus smooth muscle.
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.
Affiliation: Samsung Biomedical Research Institute and.Show MeSH
Related in: MedlinePlus
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.