Actions of barium on rapidly inactivating potassium current in bullfrog sympathetic neurons.
Whole-cell/voltage-clamp recordings were made from dissociated bullfrog sympathetic neurons to examine the inhibitory actions of barium (0.01-3 mM) on a rapidly inactivating A-type potassium current (IA). The IC50 value was about 0.9 mM. Barium (1 mM) approximately halved the maximum amplitude of IA (approximately 1.7 nA near 0 mV) without significantly affecting a voltage for the 50%-activation (approximately -40 mV) and that for the 50%-inactivation (approximately -90 mV), nor did it affected the time course of IA. The results suggest that the barium block is independent of the kinetics of the A-channels in bullfrog sympathetic neurons.
Tokimasa
T
T
Department of Physiology, Tokai University School of Medicine, Bohseidai, Isehara, Japan. tokimasa@is.icc.u-tokai.ac.jp
Nishimura
T
T
D000818:Animals; D001464:Barium / Q000494:pharmacology*; D005728:Ganglia, Sympathetic / Q000166:cytology / Q000187:drug effects*; D007700:Kinetics; D009474:Neurons / Q000187:drug effects*; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000187:drug effects*; D011892:Rana catesbeiana; D013997:Time Factors
D015221:Potassium Channels; D001464:Barium