Calcium-dependent potentiation of M-current in bullfrog sympathetic neurons.
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.
Tokimasa
T
T
Department of Physiology, Tokai University Medical School, Isehara, Japan. tokimasa@is.icc.u-tokai.ac.jp
Shirasaki
T
T
Yoshida
M
M
Ito
M
M
Tanaka
E
E
Mitsumoto
T
T
Akasu
T
T
Tanaka
M
M
Higashi
H
H
Nakano
T
T
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*
D015221:Potassium Channels; D002118:Calcium