title: Effects of berberine on intracellular free calcium in smooth muscle cells of Guinea pig colon.
abstract: 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.
authors.affiliation: Digestive Disease Research Division, RenMin Hospital of Wuhan University, 238 Jiefang Road, Wuhan 430060, China.
authors.forename: J W
authors.initials: JW
authors.lastname: Cao
authors.forename: H S
authors.initials: HS
authors.lastname: Luo
authors.forename: B P
authors.initials: BP
authors.lastname: Yu
authors.forename: X D
authors.initials: XD
authors.lastname: Huang
authors.forename: Z X
authors.initials: ZX
authors.lastname: Sheng
authors.forename: J P
authors.initials: JP
authors.lastname: Yu
mesh_terms: 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
chemical_list: D015220:Calcium Channels; D001599:Berberine; D000109:Acetylcholine; D011188:Potassium; D002118:Calcium