Signal transduction in human myometrial cells.
Calcium plays a pivotal role in the contraction-relaxation cycle of uterine smooth muscle. We investigated the effects of three uterine agonists; prostaglandin F2 alpha (PGF2 alpha), oxytocin and platelet activating factor (PAF) on intracellular levels of Ca ([Ca2+]i) in intact human myometrial cells and 45Ca2+ efflux from permeabilized myocytes. We observed that, whereas oxytocin and PAF activated the phosphoinositide cycle, generating inositol triphosphate to mobilize intracellular Ca2+, PGF2 alpha acted mainly to enhance Ca2+ influx. Oxytocin-, but not PGF2 alpha-elicited responses were suppressed by pertussis toxin. It is concluded that all three agonists act by regulating [Ca2+]i in myometrial cells, but the signal transduction mechanism of PGF2 alpha differs from that of oxytocin and PAF.
Molnár
M
M
Institute of Pathophysiology, Semmelweis University of Medicine, Budapest, Hungary. MOLMIK@SOTE.NET.HU
Rigó
J
J
Hertelendy
F
F
D002118:Calcium / Q000378:metabolism*; D002463:Cell Membrane Permeability; D002478:Cells, Cultured; D015237:Dinoprost / Q000494:pharmacology; D005260:Female; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D007700:Kinetics; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology; D009215:Myometrium / Q000187:drug effects / Q000502:physiology*; D010121:Oxytocin / Q000494:pharmacology; D010716:Phosphatidylinositols / Q000378:metabolism; D010972:Platelet Activating Factor / Q000494:pharmacology; D015398:Signal Transduction
D010716:Phosphatidylinositols; D010972:Platelet Activating Factor; D010121:Oxytocin; D015544:Inositol 1,4,5-Trisphosphate; D015237:Dinoprost; D002118:Calcium