title: Effect of 5-hydroxyindole on ethanol potentiation of 5-hydroxytryptamine (5-HT)3 receptor-activated ion current in NCB-20 neuroblastoma cells.
abstract: We examined the effect of 5-hydroxyindole (5-HI) on the potentiation of 5-hydroytryptamine (5-HT)(3) receptor function by ethanol (EtOH) so as to study whether EtOH potentiates channel function through increasing activation or blocking desensitization. We measured 5-HT(3) receptor current using a whole-cell voltage clamp technique with a method of rapid drug application in NCB-20 neuroblastoma cells. The 5-HI, an agent that block receptor desensitization, increased the decay time constant (tau), not the peak of 5-HT(3) receptor-mediated currents induced by 10 microM 5-HT. EtOH did not change the peak amplitude and tau of the current induced by 10 microM 5-HT. Coapplication of EtOH and 5-HI with 5-HT caused no increase in the peak currents, but tau was further increased. Therefore, a further block in desensitization could be induced by 5-HI, despite the presence of EtOH. These results indicate that EtOH potentiates 5-HT(3) receptor function, with these effects due at least in part by increasing channel activation rather than by blocking desensitization.
authors.affiliation: Department of Pharmacology, College of Medicine, The Catholic University of Korea, 505 Banpo-dong, Socho-gu, Seoul 137-701, South Korea.
authors.forename: Han Soo
authors.initials: HS
authors.lastname: Yang
authors.forename: Seong Yun
authors.initials: SY
authors.lastname: Kim
authors.forename: Se Joon
authors.initials: SJ
authors.lastname: Choi
authors.forename: Ki-Jung
authors.initials: KJ
authors.lastname: Kim
authors.forename: Ok Nyu
authors.initials: ON
authors.lastname: Kim
authors.forename: Sang Bok
authors.initials: SB
authors.lastname: Lee
authors.forename: Ki-Wug
authors.initials: KW
authors.lastname: Sung
mesh_terms: D000818:Animals; D004357:Drug Synergism; D000431:Ethanol / Q000494:pharmacology*; D007211:Indoles / Q000494:pharmacology*; D007473:Ion Channels / Q000502:physiology*; D051379:Mice; D009447:Neuroblastoma / Q000378:metabolism*; D011985:Receptors, Serotonin / Q000502:physiology*; D044406:Receptors, Serotonin, 5-HT3; D012701:Serotonin / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
chemical_list: D007211:Indoles; D007473:Ion Channels; D011985:Receptors, Serotonin; D044406:Receptors, Serotonin, 5-HT3; C026785:5-hydroxyindole; D012701:Serotonin; D000431:Ethanol