Tetrandrine: a novel calcium channel antagonist inhibits type I calcium channels in neuroblastoma cells.
Tetrandrine, an alkaloid isolated from the Chinese herb, Radix stephaniae tetrandrae, has been used clinically as a hypotensive agent for a long time. Recently, several studies have demonstrated that tetrandrine behaves like a calcium entry blocker. In the present investigation, the whole cell version of the patch clamp technique was used to study the effect of tetrandrine on the type I (transient inward) calcium current in neuroblastoma cells. These results showed that tetrandrine inhibited the transient inward current, without affecting the channel kinetics. The effects of tetrandrine were dose-dependent and reversible but did not depend on the frequency of stimulation (use-dependence) or the membrane potential. These data clearly demonstrate that tetrandrine is a novel and potent antagonist of the transient inward current in neuroblastoma cells.
Liu
Q Y
QY
Department of Physiology, Faculty of Medicine, University of Alberta, Edmonton, Canada.
Karpinski
E
E
Rao
M R
MR
Pang
P K
PK
D000470:Alkaloids / Q000494:pharmacology*; D000818:Animals; D001464:Barium / Q000378:metabolism; D044182:Benzylisoquinolines; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D005444:Flunarizine / Q000494:pharmacology; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D009447:Neuroblastoma / Q000378:metabolism*; D009543:Nifedipine / Q000494:pharmacology; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000378:metabolism
D000470:Alkaloids; D044182:Benzylisoquinolines; D002121:Calcium Channel Blockers; D001464:Barium; C009438:tetrandrine; D009543:Nifedipine; D005444:Flunarizine