Effects of berberine on intracellular free calcium in smooth muscle cells of Guinea pig colon.
OBJECTIVE
To investigate the effects and mechanism of berberine (Ber) on the intracellular free calcium concentration ([Ca(2+)](i)) in the smooth muscle cells of guinea pig colon.


METHODS
The changes of [Ca(2+)](i) were assayed by the biwavelength spectrophotometry with Fura 2-AM in the cell suspension of the smooth muscle cells, which were freshly isolated from guinea pig colon.


RESULTS
In the resting state, [Ca(2+)](i) in the HEPES-Ringer solution (CaCl(2) 1.5 mmol.l(-1)) was (108 +/- 9.4) nmol.l(-1) (n = 7). Ber had no significant effects on the resting [Ca(2+)](i), but markedly inhibited the increase in [Ca(2+)](i )induced by 60 mmol.l(-1) KCl in a concentration-dependent manner. The value of IC(50 )was 34.09 micromol.l(-1). 30 and 100 micromol.l(-1) Ber also inhibited the elevation of [Ca(2+)](i) evoked by 10 micromol.l(-1) Ach in a dose-dependent fashion in the presence or absence of extracellular Ca(2+). In addition, Ber inhibited the elevation of [Ca(2+)](i) stimulated by cyclopiazonic acid (CPA) in a dose-dependent manner. This effect was more potent in the HEPES-Ringer solution (IC(50) = 37.79 micromol.l(-1)) than Ca(2+)-free medium (IC(50) = 49.70 micromol.l(-1)).


CONCLUSIONS
Ber possessed an inhibitory effect on the influx of extracellular Ca(2+) and Ca(2+)-release from intracellular stores in the smooth muscle cells of colon. That is to say Ber may be a blocker of Ca(2+) channels.
Cao
J W
JW
Digestive Disease Research Division, RenMin Hospital of Wuhan University, 238 Jiefang Road, Wuhan 430060, China.
Luo
H S
HS
Yu
B P
BP
Huang
X D
XD
Sheng
Z X
ZX
Yu
J P
JP
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001599:Berberine / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000187:drug effects; D003106:Colon / Q000187:drug effects / Q000378:metabolism; D006168:Guinea Pigs; D007424:Intracellular Fluid / Q000378:metabolism*; D009130:Muscle, Smooth / Q000187:drug effects* / Q000378:metabolism; D011188:Potassium / Q000494:pharmacology
D015220:Calcium Channels; D001599:Berberine; D000109:Acetylcholine; D011188:Potassium; D002118:Calcium