Fig. 1.

Characterization of oxytocin-stimulated PLC-signaling in ULTR and primary human uterine smooth muscle cells. Concentration-response relationships for oxytocin- and histamine-stimulated total [³H]inositol phosphate accumulations in primary (A and B) and ULTR (C) cells. [³H]Inositol phosphate accumulation was stimulated by addition of increasing oxytocin (0.1–1000 nm) or histamine (0.1–1000 μm) concentrations for 20 min under lithium blockade (see Materials and Methods). Individual curves are shown from each patient donor cell preparation indicated PT1–4 (A and B), or as mean data for ULTR cell responses (C). To assess oxytocin-stimulated Ca²⁺ responses (D), cells were Fluo4-AM-loaded (see Materials and Methods) and stimulated with increasing concentrations of oxytocin (0.01–1000 nm). [Ca²⁺]_i changes were measured as increased cytosolic fluorescence and expressed as fold-over-basal. Data are shown as means ± sem for n = 4 for ULTR cells and three patient donors for the primary preparations.