[Effects of panaxatriol saponins (PTS) isolated from panax notoginseng on the action potential and delayed rectifier current (Ix) in sheep cardiac Purkinje fibers].
The electrophysiological effects of PTS in sheep cardiac Purkinje fibers were studied. PTS was shown to increase the duration of action potential (APD30, APD50 and APD90) at the concentrations of 2.5 micrograms/ml and 5.0 micrograms/ml. However, the amplitude of action potential (APA) remained unchanged. The result of using double microelectrode voltage clamp method showed that PTS (1.25-10.0 micrograms/ml) depressed the delayed (outward) rectifier current (Ix) in time- and dose-dependent manners, when the holding potential was held at +20 mV, the command potential was held at +10 mV, 0.2 Hz and the clamping time at 1-1.5 s. It may be concluded that the effect of PTS on APD is mainly related to blocking the delayed rectifier potassium channel.
Li
X J
XJ
Department of Pharmacology, Beijing Medical University.
Fan
J S
JS
Liu
Y W
YW
Zhang
B H
BH
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology*; D036145:Ginsenosides; D015221:Potassium Channels / Q000187:drug effects*; D011690:Purkinje Fibers / Q000187:drug effects* / Q000502:physiology; D012756:Sheep; D014315:Triterpenes / Q000494:pharmacology*
D000889:Anti-Arrhythmia Agents; D036145:Ginsenosides; D015221:Potassium Channels; D014315:Triterpenes; C004563:panaxatriol