title: Inhibition of uterine contractility with various tocolytics with and without progesterone: in vitro studies.
abstract: OBJECTIVE
  Various tocolytics are used to suppress uterine contractility in patients in preterm labor. Progesterone (P4) is used in patients at high risk for preterm delivery. In this study, we evaluated the effects of various tocolytics with and without P4 to examine effects on uterine contractility.
  
  
  METHODS
  Uterine tissues (n = 280) from women undergoing cesarean at term were exposed in vitro to various agents (vehicle, magnesium sulfate [MgSO(4)], nifedipine, indomethacin, or pinacidil-all with and without P4). Contractility was measured before and after addition of the various agents.
  
  
  RESULTS
  P4 alone at 10(-5) mol/L concentration has little effect to inhibit contractility (P ≥ .05). MgSO(4) (2-8 × 10(-3) mol/L) inhibits uterine contractility (P < .05) but there is no change when combined with P4 (P > .05). Nifedipine (10(-8) mol/L) and indomethacin (10(-5) mol/L) inhibit contractions alone (P < .05) and to a greater extent when combined with P4 (P < .05). P4 significantly (P < .05) reduced the effects of pinacidil (10(-6.5) mol/L).
  
  
  CONCLUSIONS
  Combinations of P4 with nifedipine or indomethacin, but not MgSO(4), might be used to effectively suppress preterm labor.
authors.affiliation: Department of Obstetrics and Gynecology, and Women's Health, Maricopa Integrated Health System, Phoenix, AZ 85008, USA. Jennifer_Baumbach@dmgaz.org.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Baumbach
authors.forename: Shao-Qing
authors.initials: SQ
authors.lastname: Shi
authors.forename: Leili
authors.initials: L
authors.lastname: Shi
authors.forename: James
authors.initials: J
authors.lastname: Balducci
authors.forename: Dean V
authors.initials: DV
authors.lastname: Coonrod
authors.forename: Robert E
authors.initials: RE
authors.lastname: Garfield
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D007213:Indomethacin / Q000494:pharmacology; D008278:Magnesium Sulfate / Q000494:pharmacology; D009215:Myometrium / Q000187:drug effects*; D009543:Nifedipine / Q000494:pharmacology; D007752:Obstetric Labor, Premature / Q000517:prevention & control*; D020110:Pinacidil / Q000494:pharmacology; D011247:Pregnancy; D011374:Progesterone / Q000494:pharmacology*; D015149:Tocolytic Agents / Q000494:pharmacology*; D014590:Uterine Contraction / Q000187:drug effects*
chemical_list: D015149:Tocolytic Agents; D011374:Progesterone; D008278:Magnesium Sulfate; D020110:Pinacidil; D009543:Nifedipine; D007213:Indomethacin