title: Tramadol-induced blockade of delayed rectifier potassium current in NG108-15 neuronal cells.
abstract: Tramadol is a centrally acting analgesic drug used mainly in the moderate to severe pain control. In this study, the effects of this agent on ion currents of NG108-15 neuronal cells were investigated. This cell line expresses Kv3.1a mRNAs and exhibits the activity of delayed rectifier K(+) (K(DR)) channels. Tramadol suppressed the amplitude of delayed rectifier K(+) current (I(K(DR))) in a concentration-dependent manner with an IC(50) values of 25 microM. Tramadol (30 microM) also shifted the steady-state inactivation of I(K(DR)) to a more negative membrane potential by approximately -15 mV. The role of the K(DR) channel, particularly as a member of the Kv3 superfamily, is to stabilize the resting potential and to reduce the width of action potentials in the time-coding neurons. Tramadol-induced block of I(K(DR)) observed in this study could be partly responsible for its anti-depressant action.
authors.affiliation: Department of Anesthesiology, National Cheng Kung University Medical College, No. 1 Ta-Hsueh Road, Tainan, Tainan City 704, Taiwan, ROC.
authors.forename: Tung-Ying
authors.initials: TY
authors.lastname: Tsai
authors.forename: Yu-Chuan
authors.initials: YC
authors.lastname: Tsai
authors.forename: Sheng-Nan
authors.initials: SN
authors.lastname: Wu
authors.forename: Yen-Chin
authors.initials: YC
authors.lastname: Liu
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000701:Analgesics, Opioid / Q000494:pharmacology; D000818:Animals; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002490:Central Nervous System / Q000187:drug effects / Q000503:physiopathology; D006825:Hybridomas; D008297:Male; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D010146:Pain / Q000188:drug therapy / Q000503:physiopathology; D026902:Potassium Channel Blockers / Q000494:pharmacology*; D015221:Potassium Channels / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D014147:Tramadol / Q000494:pharmacology*
chemical_list: D000701:Analgesics, Opioid; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D014147:Tramadol