Platelet-activating factor-induced intracellular calcium waves in human uterine myometrial cells.

OBJECTIVE: We visualized and investigated the intracellular calcium waves propagated by platelet-activating factor (PAF) in cultured human myometrial cells. STUDY DESIGN: Myometrial cells were stimulated with PAF ranging between 10(-8) and 10(-15) M. For the observation of calcium waves, calcium green-1 and a confocal laser microscopy were used. Cells were also stimulated with 10(-9) M of PAF in a calcium-free solution. RESULTS: In physiological solution, PAF at concentrations ranging between 10(-9) and 10(-15) M induced intracellular calcium waves. Mean wave speed was 16.1+/-5.6 microm/s. Wave speeds were independent of the PAF concentration. Similar results were observed in the absence of added calcium, with the exception that the wave speeds were significantly slower (7.3+/-3.3 microm/s). CONCLUSIONS This is the first study to demonstrate the calcium waves propagated by PAF stimulation in human myometrial cells. These observations further support the proposed role of PAF in parturition.

Immunohistochemical localization of polo like kinase in early human placenta.

Polo like kinase (PLK) is the kinase that was first cloned by us from the cDNA library of human placenta. It belongs to the serine/threonine kinase family and plays a very important role in cell proliferation. In this study, the localization of PLK in early human placenta in vivo was investigated. Immunostaining revealed PLK protein in syncytiotrophoblastic cells and extravillous trophoblastic cells; however proliferating cell nuclear antigen was not. It is known that cytotrophoblastic cells proliferate highly in early human placental villi; however, PLK was not detected in those cells. These results suggest that PLK plays a different role in syncytiotrophoblastic cells than it does in other proliferating cells.