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: Apamin, a SK channel blocker, is known to induce depolarization in various regions of gastrointestinal smooth muscles (19). However, it has also been reported that apamin had no effect on the RMP in guinea pig antrum (19). The effect of apamin in HGCS has not been studied. Apamin (300 nM–1 μM, n = 5 each concentration) did not affect the RMP, amplitude, and frequency of SWP in HGCS (Fig. 4), suggesting that the basal activation of SK channels in regulating RMP is negligible.