['The aim of this study was to investigate the ability of serotonin to increase contractions in human myometrium.', 'Isometric tension measurements were used to determine the effect of increasing doses of serotonin on strips of human myometrium obtained at the time of cesarean section.', 'Serotonin had little or no effect on the spontaneous activity of myometrium strips in control conditions. In tissue where this activity had been reduced by either forskolin or diazoxide, serotonin caused a dose-dependent increase in contractions and produced up to a 3-fold increase in contractions over basal activity.'] Is stimulation of contractions in human myometrium by serotonin unmasked by smooth muscle relaxants?