[Level of urocortin mRNA during labor and effect of urocortin on myometrial contractility in vitro].

OBJECTIVE

To examine the expression of urocortin mRNA during labor and the effect of urocortin on myometrial contractility, and to investigate its role in the onset and progress of labor.

METHODS

(1) Semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR), using beta-actin as internal standard was applied to determine the levels of urocortin mRNA in human placenta and myometrium from the group of cesarean section before (10 cases) and during (10 cases in latent phase and 10 cases in active phase) labor. (2) The isolated myometrial strips of pregnant women (n = 24) were prepared. The effects of urocortin with or without prostaglandin F(2alpha) (PGF(2alpha)) and oxytocin on myometrial contractility were evaluated by areas under the curve.

RESULTS

(1) Semi-quantitative RT-PCR showed that the expression level of urocortin mRNA in placenta and myometrium after the onset of labor were higher than before labor (1.23 +/- 0.52, 1.32 +/- 0.22; 0.83 +/- 0.38, 0.94 +/- 0.13, respectively, P < 0.05). (2) Urocortin itself did not affect myometrial tension development at all concentrations tested, but it markedly increased PGF(2alpha)-induced myometrial contractility. The average area under the curve of controls was (2.12 +/- 0.15) cm(2) and of study strips was (3.90 +/- 0.33) cm(2) (P < 0.05); urocortin did not increase the myometrial response to oxytocin compared with controls (P > 0.05).

CONCLUSION

The study indicates urocortin may indirectly modulate myometrial contractility during labor.