title: Calcium-dependent potentiation of M-current in bullfrog sympathetic neurons.
abstract: Whole-cell voltage-clamp recordings were made from cultured bullfrog sympathetic neurons to measure the steady-state activation curve of M-type potassium current. When measured with a calcium-deficient (10 nM) pipette solution M-conductance was 4.8 nS at -35 mV having the 50%-activation voltage at-20 mV. Respective values were 17.2 nS at -35 mV with the 50%-activation voltage at -42 mV when measured with a calcium-rich (1 microM) solution, indicating the hyperpolarizing displacement of the activation curve with high internal calcium. It is suggested that intracellular calcium ions can modulate kinetics of M-current which thereby regulate the number of M-channels being open at given membrane potentials.
authors.affiliation: Department of Physiology, Tokai University Medical School, Isehara, Japan. tokimasa@is.icc.u-tokai.ac.jp
authors.forename: T
authors.initials: T
authors.lastname: Tokimasa
authors.forename: T
authors.initials: T
authors.lastname: Shirasaki
authors.forename: M
authors.initials: M
authors.lastname: Yoshida
authors.forename: M
authors.initials: M
authors.lastname: Ito
authors.forename: E
authors.initials: E
authors.lastname: Tanaka
authors.forename: T
authors.initials: T
authors.lastname: Mitsumoto
authors.forename: T
authors.initials: T
authors.lastname: Akasu
authors.forename: M
authors.initials: M
authors.lastname: Tanaka
authors.forename: H
authors.initials: H
authors.lastname: Higashi
authors.forename: T
authors.initials: T
authors.lastname: Nakano
mesh_terms: D000818:Animals; D002118:Calcium / Q000502:physiology*; D004594:Electrophysiology; D066298:In Vitro Techniques; D007700:Kinetics; D008564:Membrane Potentials / Q000502:physiology; D009474:Neurons / Q000502:physiology*; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000502:physiology*; D011892:Rana catesbeiana; D013564:Sympathetic Nervous System / Q000166:cytology / Q000502:physiology*
chemical_list: D015221:Potassium Channels; D002118:Calcium