Ineffectiveness of oxytocin on intercellular communication between term pregnant human myometrial cells before labor.
OBJECTIVE
The effects of the uterotonic agent oxytocin on intercellular communication between term pregnant human myometrial cells before labor were studied to investigate its contribution to the synchronicity of uterine contractions.


METHODS
The membrane potential and the input resistance of myometrial cells were measured with intracellular micropipettes, and dye-coupling assays were concomitantly performed while the tissues were perfused with three concentrations of oxytocin (10(-8) mol/L, 10(-7) mol/L, and 10(-6) mol/L). The results were compared with those obtained from tissues perfused with gap junctional uncoupling agent octanol and those with Tyrode's solution (control).


RESULTS
Octanol increased input resistance and inhibited dye coupling but did not affect membrane potential compared with controls. Oxytocin depolarized membrane potential at all studied concentrations. The mean input resistance values and detectable dye propagation with oxytocin were similar to controls.


CONCLUSIONS
Oxytocin does not contribute to gap junctional intercellular communication in term pregnant human myometrium before labor but may affect contractions by depolarizing membrane potential.
Ciray
H N
HN
Department of Obstetrics and Gynecology, University Hospital in Uppsala, Sweden.
Bäckström
T
T
Ulmsten
U
U
D002450:Cell Communication / Q000187:drug effects*; D017097:Electric Impedance; D005260:Female; D005452:Fluoresceins; D005456:Fluorescent Dyes; D006801:Humans; D007743:Labor, Obstetric; D008564:Membrane Potentials / Q000187:drug effects; D008856:Microscopy, Fluorescence; D009215:Myometrium / Q000166:cytology*; D000442:Octanols / Q000494:pharmacology; D010121:Oxytocin / Q000494:pharmacology*; D011247:Pregnancy
D005452:Fluoresceins; D005456:Fluorescent Dyes; D000442:Octanols; C024098:6-carboxyfluorescein; D010121:Oxytocin