title: Shakuyaku-kanzo-to inhibits smooth muscle contractions of human pregnant uterine tissue in vitro.
abstract: OBJECTIVE
  Shakuyaku-kanzo-to (SK) is a herbal medicine and is known to possess an antispasmodic effect on skeletal muscle and intestinal smooth muscle. However, it is unclear whether SK is effective in antagonizing uterine smooth muscle contractions. Herein, we investigated the effects of SK on smooth muscle contractions of human pregnant uterine samples.
  
  
  METHODS
  We prepared myometrial strips from uterine tissues of pregnant women who underwent cesarean section for obstetrical indications, and examined the inhibitory effects of SK and its components, shakuyaku (S) and kanzo (K), on agonist-induced and spontaneous contractions in vitro. Oxytocin, prostaglandinF(2α) , and high KCl were utilized as agonists in this study.
  
  
  RESULTS
  SK inhibited agonist-induced and spontaneous contractions in a dose-dependent manner. Inhibition of SK on oxytocin-induced contractions occurred at a concentration of 100 µg/mL and reached maximum effect at a concentration of more than 1000 µg/mL. The half max inhibitory concentration of SK was approximately 440 µg/mL in oxytocin-induced contractions. SK at 1000 µg/mL completely inhibited the oxytocin- and prostaglandinF(2α)-induced contractions but not the high KCl-induced contractions. The inhibitory effects on agonist-induced contractions of K, but not S, matched those of SK.
  
  
  CONCLUSIONS
  These results suggest that the inhibitory effect of SK on smooth muscle contractions is due to K. The mechanism of the inhibitory effects of SK on oxytocin- and prostaglandinF(2α) -induced contractions may differ from that on KCl-induced contractions.
authors.affiliation: Department of Obstetrics and Gynecology, Kansai Medical University, 10-15 Fumizono-cho,Moriguchi, Osaka, Japan.
authors.forename: Shoko
authors.initials: S
authors.lastname: Tsuji
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Yasuda
authors.forename: Genichiro
authors.initials: G
authors.lastname: Sumi
authors.forename: Hisayuu
authors.initials: H
authors.lastname: Cho
authors.forename: Tomoko
authors.initials: T
authors.lastname: Tsuzuki
authors.forename: Hidetaka
authors.initials: H
authors.lastname: Okada
authors.forename: Hideharu
authors.initials: H
authors.lastname: Kanzaki
mesh_terms: D000328:Adult; D004338:Drug Combinations; D004365:Drugs, Chinese Herbal / Q000494:pharmacology*; D005260:Female; D006035:Glycyrrhiza / Q000737:chemistry*; D006801:Humans; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects*; D009215:Myometrium / Q000187:drug effects*; D010120:Oxytocics / Q000037:antagonists & inhibitors / Q000494:pharmacology; D029596:Paeonia / Q000737:chemistry*; D010276:Parasympatholytics / Q000494:pharmacology; D011247:Pregnancy; D015149:Tocolytic Agents / Q000494:pharmacology*; D055815:Young Adult
chemical_list: D004338:Drug Combinations; D004365:Drugs, Chinese Herbal; D010120:Oxytocics; D010276:Parasympatholytics; D015149:Tocolytic Agents; C038462:shakuyaku-kanzoh-toh