title: [Inhibitory effects of 17beta-estradiol on spontaneous and activated contraction of rat uterus smooth muscle].
abstract: OBJECTIVE
  To observe and compare the effects of 17beta-estradiol (EST) on the phasic and tonic contractile activities of the uterine smooth muscles of SD rats in vitro.
  
  
  METHODS
  Different concentrations of 17beta-estradiol were added into the perfusion muscular sockets containing uterine smooth muscles of SD rats, and the activities of muscle contraction were recorded at the same time.
  
  
  RESULTS
  17beta-estradiol had obvious depression effects on spontaneous rhythmic contraction of the uterine smooth muscles in a concentration-dependent manner, it could considerably decrease muscular tension, the mean amplitudes and frequencies of contractile waves (P < 0.01); it could also suppress the uterine contraction stimulated by KCl, CaCl2 or prostaglandin F2alpha (PGF2alpha). Based on the contraction of uterine smooth muscle stimulated by KCl, IC50 was 7.278 micromol/L and pD2 was -0.862 when calculated by linear regression method. 17beta-estradiol could also inhibit the maximal CaC12 contraction of uterine smooth muscle in the Ca2+ free Krebs solution, which the ECQ was 1.422 x 10(-3) mol/L, pD2 was 2.847 (control), but the E50 was 3.028 x 10(-3) mol/L, p2 was 2.519 (added with EST) when calculated by linear regression method.
  
  
  CONCLUSIONS
  The depression effects of 17beta-estradiol on the spontaneous rhythmic contraction and activated contraction of the uterine smooth muscles of SD rats could be mediated through the blockage of C2+ influx through potential-dependent Ca2+ channels of plasma membrane.
authors.affiliation: Department of Physiology, College of Basic Medicine, Lanzhou University, China.
authors.forename: Qin
authors.initials: Q
authors.lastname: Ma
authors.forename: Hong-Fang
authors.initials: HF
authors.lastname: Li
authors.forename: Shan
authors.initials: S
authors.lastname: Jin
authors.forename: Xing-Cheng
authors.initials: XC
authors.lastname: Dou
authors.forename: Ying-Fu
authors.initials: YF
authors.lastname: Zhang
authors.forename: Li-Xue
authors.initials: LX
authors.lastname: Zhang
authors.forename: Zhong-Rui
authors.initials: ZR
authors.lastname: Du
mesh_terms: D000818:Animals; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D009130:Muscle, Smooth / Q000187:drug effects*; D009215:Myometrium / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D014590:Uterine Contraction / Q000187:drug effects*
chemical_list: D004958:Estradiol