EXPRESSION OF THE GAP JUNCTION PROTEIN CONNEXIN-43 IS INCREASED IN THE HUMAN MYOMETRIUM TOWARD TERM AND WITH THE ONSET OF LABOR

OBJECTIVES: Our aim was to determine the temporal pattern of expressio n of transcripts encoding the myometrial gap junction protein connexin -43 in the human myometrium during late pregnancy and with the onset o f labor. We also correlated these data with levels of total connexin-4 3 protein and the appearance of gap junctions within the myometrial ce ll membrane. STUDY DESIGN: Myometrial tissue was collected during cesa rean section from 27 women between 37 and 41 weeks of gestation not in labor and from 7 women between 39 and 41 weeks during active labor. T he levels of connexin-43 messenger ribonucleic acid and protein were e stimated by Northern and Western analysis, respectively. The appearanc e of gap junctions between myometrial cells was assessed by immunofluo rescence of histologic sections of myometrium from these women. RESULT S: Levels of connexin-43 messenger ribonucleic acid in myometrial tiss ue collected from women not in labor increased (p < 0.01) between 37 a nd 40 weeks' gestation with a further significant increase occurring d uring labor (p < 0.05). The level of connexin-43 protein decreased (p < 0.05) during late pregnancy and was not increased during labor altho ugh gap junctions (which were not present during pregnancy) did appear in the myometrial cell membrane during labor. CONCLUSIONS: These data suggest that the mechanisms responsible for the increased myometrial cell-cell communication necessary for the development of effective lab or contractions likely involves regulation at the level of both messen ger ribonucleic acid and gap junction formation in the cell membrane.