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. STUDY DESIGN: 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. CONCLUSION: Oxytocin does not contribute to gap junctional intercellular communication in term pregnant human myometrium before labor but may affect contractions by depolarizing membrane potential.