Effects of toquipidine on ionic channels of cultured embryonic Xenopus laevis myoblasts and neurons.
OBJECTIVE
To study the effects of toquipidine (1-p-methyl-phenyl-2-(alpha-piperidinoacetyl)-1, 2, 3, 4-tetrahydroisoquinoline hydrochloride, Toq), a new anti-arrhythmic agent first synthesized in China, on ionic channels.


METHODS
Ionic channel currents were recorded by whole-cell patch clamp technique in cultured embryonic Xenopus laevis myoblasts and neurons.


RESULTS
Toq (0.1, 1, 10, and 100 mumol L-1) caused a concentration-dependent inhibition of the Na+ currents with IC50 7.2 mumol L-1 (5.3-9.8 mumol L-1). Toq (10 mumol L-1) also suppressed the high-voltage-activated Ca2+ currents in neurons. But the steady-state outward K+ currents in myoblasts were activated by Toq (10 mumol L-1).


CONCLUSIONS
Toq blocked the Na+ and Ca2+ channels and opened the steady-state outward K+ channels.
Zheng
P
P
Department of Pharmacology, Shanghai Medical University, China.
Chen
G
G
Shi
N C
NC
Zhou
S P
SP
Lu
Y Q
YQ
Yao
M H
MH
He
Z Y
ZY
D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology*; D015220:Calcium Channels / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004625:Embryo, Nonmammalian; D007473:Ion Channels / Q000187:drug effects*; D007546:Isoquinolines / Q000494:pharmacology*; D009132:Muscles / Q000166:cytology; D009474:Neurons; D010880:Piperidines / Q000494:pharmacology*; D015221:Potassium Channels / Q000187:drug effects; D015222:Sodium Channels / Q000187:drug effects; D044005:Tetrahydroisoquinolines; D014982:Xenopus laevis
D000889:Anti-Arrhythmia Agents; D015220:Calcium Channels; D007473:Ion Channels; D007546:Isoquinolines; D010880:Piperidines; D015221:Potassium Channels; D015222:Sodium Channels; D044005:Tetrahydroisoquinolines; C073853:toquipidine