Shortening increases spontaneous contractility in myometrium from pregnant women at term.
OBJECTIVE
The purpose of this study was to determine whether shortening alters spontaneous contractility in myometrial strips that are obtained from pregnant women.


METHODS
Isometric contractions were measured in myometrial strips that were obtained at cesarean delivery from 14 pregnant women at term. After 2 hours of stretching, the strip lengths were decreased by 4%, 6%, or 8%. Spontaneous contractility was measured for 120 minutes with or without prostaglandin synthase inhibitor indomethacin (10 -5 mol/L), and the cumulative concentration response to oxytocin was determined.


RESULTS
Contractility was increased by 29% and 34% in strips that shortened by 4% and 6%, respectively. Preincubation with indomethacin increased contractility by 15% in stretched strips and decreased contractility by 30% and 19% in 4% and 6% strips, respectively. Contraction frequency was increased by 26% and 53% for the strips that were shortened to 6% and 8%, respectively. These increases were prevented by indomethacin. The oxytocin responses were similar at all lengths.


CONCLUSIONS
Shortening of myometrial strips from pregnant women at term increases spontaneous contractility by a mechanism that apparently involves prostaglandins.
Hurd
William W
WW
Department of Obstetrics and Gynecology, Wright State University School of Medicine, Dayton, Ohio 45409, USA. william.hurd@wright.edu
Gibbs
Shawn G
SG
Ventolini
Gary
G
Horowitz
Gary M
GM
Guy
Stephen R
SR
D000704:Analysis of Variance; D002585:Cesarean Section; D005260:Female; D006801:Humans; D007213:Indomethacin / Q000494:pharmacology*; D009119:Muscle Contraction / Q000187:drug effects* / Q000502:physiology*; D009215:Myometrium / Q000187:drug effects* / Q000502:physiology; D009924:Organ Culture Techniques; D010121:Oxytocin / Q000494:pharmacology*; D011247:Pregnancy; D011336:Probability; D012494:Sampling Studies; D012680:Sensitivity and Specificity; D047929:Term Birth; D013997:Time Factors; D014590:Uterine Contraction / Q000187:drug effects / Q000502:physiology
D010121:Oxytocin; D007213:Indomethacin