Figure 1.

Urotensin-II activates UTS2R and induces store-operated Ca²⁺ influx. (A) Representative traces presented as fura-2 ratio (F340/F380) in aortic VSMCs and summary data of UII induced [Ca²⁺]_i mobilization in isolated VSMCs. UII (100 nM) was applied 3–4 min in the absence of extracellular Ca²⁺ and then Ca²⁺ (2 mM) was added as indicated. Traces are for VSMCs treated with UII (control), for cells pre-incubated 10 min with Urantide (100 nM), or with PLC inhibitor (U73122, 50 µM). (B) Left panel illustrates representative recordings of the changes in [Ca²⁺]_i. UII (100 nM) or thapsigargin (TG, 2 μM) were applied as indicated in (A). Traces are for VSMCs treated with UII or TG, and for cells incubated with UII and treated with 2APB (+2APB, 50 μM) 1–2 min before Ca²⁺ addition as indicated by ‘*’. Right panel shows summary data of experiments illustrated in left. ‘basal’ is for Ca²⁺ influx in untreated VSMCs, and ‘+Gd³⁺’ is for Ca²⁺ influx recorded in cells pre-incubated 3 min with gadolinium (5 μM). (C) Representative recordings (black trace) and summary data of the effects of ML9 (25 and 50 μM respectively) applied after Ca²⁺ influx induced by UII (100 nM). The addition of vehicule (grey trace) rather than ML9 had no effect on Ca²⁺ influx. The summary data in (A, B, and C) correspond to large number of cells (n = 60–220 cells) from 4–12 primary cultures. Data are means ± SEM.