Contraction of Cultured Human Uterine Smooth Muscle Cells after Stimulation with Endothelin-1

To our knowledge, the problem of how to maintain isolated smooth cells in a "contractile" phenotypic state without deviation after subculturing has yet to be resolved. The present study characterized the in vitro contractile response of human uterine smooth muscle cell to endothelin-1, which induces contractions in isolated uterine strips. Contractile effects were qualitatively investigated using silicone rubber substrata. Endothelin-1 was able to distort and reduce the wrinkles in the silicone surface. Contractions were also quantified by measuring the resulting change in the collagen lattice area. Endothelin-1 significantly increased the contractile response in a dose-dependent manner by selectively activating endothelin A receptors. When myometrial cells were cultured within collagen lattices, a microfilament-disrupting agent, cytochalasin B, abolished contractions, and no change was observed in smooth muscle (alpha)-actin immunostaining. Taken together, these observations show that the uterine smooth muscle cells are contractile and respond appropriately to a potent uterotonic agent. Based on these findings, a cultured uterine smooth muscle cell model, which could be used to elucidate the mechanisms controlling uterine activity, is proposed.