QUANTITATIVE IMMUNOCONFOCAL ANALYSIS OF HUMAN MYOMETRIAL GAP JUNCTIONCONNEXIN43 IN RELATION TO STEROID-HORMONE CONCENTRATIONS AT TERM LABOR

The aim of this study Was to quantify gap junction expression in the h uman myometrium in relation to progesterone and oestradiol concentrati ons, and to establish whether oxytocin-resistant dystocia is due to an abnormality in gap junction expression. Three groups of patients were investigated: (i) before labour (at term), (ii) normal labour and (ii i) oxytocin-resistant dystocia (eight patients per group). For each pa tient, the concentrations of oestradiol and progesterone in maternal b lood and in myometrial tissue were measured, and the number and area o f immunostained connexin43 gap junctions per unit volume of tissue det ermined by quantitative analysis of digital images obtained by confoca l microscopy. No significant difference in connexin43 gap junction con tent was observed between the three patient groups. When all groups we re pooled, there was a significant positive correlation (P < 0.05) bet ween the quantity of immunolabelled gap junctions and the oestradiol:p rogesterone ratio, but there was no significant difference in this cor relation between the groups. Gap junction immunolabelling was not corr elated with the progesterone or oestradiol concentration in the matern al blood or the myometrium. These data suggest that in human myometriu m: (i) dystocia is not due to a reduced level of immunodetectable conn exin43 gap junctions, (ii) onset of labour is not associated with a su dden increase in immunodetectable gap junction protein and (iii) gap j unctions can be expressed in the presence of high progesterone concent rations.