Effects of tetrandrine on calcium and potassium currents in isolated rat hepatocytes.
OBJECTIVE
To study the effects of tetrandrine (Tet) on calcium release-activated calcium current (I(CRAC)), delayed rectifier potassium current (I(K)), and inward rectifier potassium currents (I(K1)) in isolated rat hepatocytes.


METHODS
Hepatocytes of rat were isolated by using perfusion method. Whole cell patch-clamp techniques were used in our experiment.


RESULTS
The peak amplitude of I(CRAC) was -508+/-115 pA (n=15), its reversal potential of I(CRAC) was about 0 mV. At the potential of -100 mV, Tet inhibited the peak amplitude of I(CRAC) from -521+/-95 pA to -338+/-85 pA (P<0.01 vs control, n=5), with the inhibitory rate of 35 % at 10 micromol/L and from -504+/-87 pA to -247+/-82 pA (P<0.01 vs control, n=5), with the inhibitory rate of 49 % at 100 micromol/L, without affecting its reversal potential. The amplitude of I(CRAC) was dependent on extracellular Ca(2+) concentration. The peak amplitude of I(CRAC) was -205+/-105 pA (n=3) in tyrode's solution with Ca(2+) 1.8 mmol/L (P<0.01 vs the peak amplitude of I(CRAC) in external solution with Ca(2+) 10 mmol/L). Tet at the concentration of 10 and 100 micromol/L did not markedly change the peak amplitude of delayed rectifier potassium current and inward rectifier potassium current (P>0.05 vs control).


CONCLUSIONS
Tet protects hepatocytes by inhibiting I(CRAC), which is not related to I(K) and I(K1).
Zhou
Hong-Yi
HY
Department of Pharmacology,Tongji medical college of Huazhong university of science and technology, Wuhan 430030, Hubei Province, China. zhouhy518@yahoo.com.cn
Wang
Fang
F
Cheng
Lan
L
Fu
Li-Ying
LY
Zhou
Ji
J
Yao
Wei-Xing
WX
D000470:Alkaloids / Q000494:pharmacology*; D000818:Animals; D044182:Benzylisoquinolines; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D015220:Calcium Channels / Q000378:metabolism*; D002478:Cells, Cultured; D004365:Drugs, Chinese Herbal / Q000494:pharmacology; D005260:Female; D022781:Hepatocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D008297:Male; D008564:Membrane Potentials / Q000502:physiology; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
D000470:Alkaloids; D044182:Benzylisoquinolines; D002121:Calcium Channel Blockers; D015220:Calcium Channels; D004365:Drugs, Chinese Herbal; D015221:Potassium Channels; C009438:tetrandrine