Effects of tetrandrine on cytosolic free calcium concentration in corpus cavernosum smooth muscle cells of rabbits.
OBJECTIVE
To study the relaxation mechanisms of tetrandrine (Tet) on the corpus cavernosum smooth muscle.


METHODS
The corpus cavernosum smooth muscle cells from New Zealand white rabbits were cultured in vitro. [Ca(2+)](i) was measured by Fluorescence Ion Digital Imaging System, using Fluo-2/AM as a Ca(2+)-sensitive fluorescent indicator.


RESULTS
Tet (1, 10 and 100 micromol/L) had no effect on the resting [Ca(2+)](i) (P>0.05). In the presence of extracellular Ca(2+) (2.5 mmol/L), Tet (1, 10 and 100 micromol/L) inhibited [Ca(2+)](i) elevation induced by high K(+) and phenylephrine (PE) in a concentration-dependent manner (P>0.05). In calcium free solution containing egtaic acid, Tet (1 and 10 micromol/L) had no inhibitory effects on [Ca(2+)](i) elevation induced by PE (P>0.05). However, Tet (100 micromol/L) inhibited [Ca(2+)](i) elevation induced by PE (P>0.05).


CONCLUSIONS
Tet inhibited the Ca(2+) influx from the extracellular site via voltage-activated Ca(2+) channel and alpha(2)-adrenoceptor-operated Ca(2+) channel. At a high concentration, Tet might inhibit the cytosolic calcium pool release in cultured corpus cavernosum smooth muscle cells. This inhibitory action on [Ca(2+)](i) might be one of the relaxation mechanisms of Tet on the corpus cavernosum smooth muscle.
Liu
Ji-Hong
JH
Department of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China. jhliu@tjh.tjmu.edu.cn
Chen
Jun
J
Wang
Tao
T
Liu
Bo
B
Yang
Jun
J
Chen
Xiao-Wen
XW
Wang
Shao-Gang
SG
Yin
Chun-Ping
CP
Ye
Zhang-Qun
ZQ
D000470:Alkaloids / Q000494:pharmacology*; D000818:Animals; D044182:Benzylisoquinolines / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D003600:Cytosol / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D009126:Muscle Relaxation; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism*; D010413:Penis / Q000166:cytology / Q000378:metabolism*; D010656:Phenylephrine / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D011817:Rabbits
D000470:Alkaloids; D044182:Benzylisoquinolines; D010656:Phenylephrine; C009438:tetrandrine; D011189:Potassium Chloride; D002118:Calcium