Effect of new O-superfamily conotoxin SO3 on sodium and potassium currents of cultured hippocampal neurons.
The effects of a new O-superfamily conotoxin SO3 on sodium and potassium currents were examined in cultured rat hippocampal neurons using the whole-cell patch clamp technique. SO3 caused a concentration-dependent, rapidly developing and reversible inhibition of sodium currents (I(Na)). The IC(50) value for the blockage of I(Na) was calculated to be 0.49 and the Hill coefficient was 1.7. Using electrophysiological and pharmacological protocols, transient A-type potassium currents (I(A)) and delayed rectifiers potassium currents (I(K)) were isolated. SO3 caused a concentration-dependent, and reversible inhibition of I(K). The IC(50) value for the blockage of I(K) was calculated to be 1.6 and the Hill coefficient was 0.6, with no significant effect on I(A). These results indicate that SO3 can selectively inhibit neuronal sodium and potassium currents.
Li
Zhan
Z
Department of Biological Science and Technology, Tsinghua University, Beijing 100084, China.
He
Xiang-Ping
XP
Xie
Zuo-Ping
ZP
Dai
Qiu-Yun
QY
Huang
Pei-Tang
PT
D000595:Amino Acid Sequence; D000818:Animals; D002478:Cells, Cultured; D020916:Conotoxins / Q000737:chemistry / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004622:Embryo, Mammalian; D006624:Hippocampus / Q000187:drug effects* / Q000502:physiology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000502:physiology; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D015221:Potassium Channels / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015222:Sodium Channels / Q000502:physiology*
D020916:Conotoxins; D015221:Potassium Channels; D015222:Sodium Channels