Figure 4.

Inhibition of 10 nM hU-II (human urotensin-II)-induced [Ca²⁺]_i mobilization in recombinant hUT (human urotensin-II receptor)-CHO (Chinese hamster ovary) cells by (a) SB-657510 and (b) palosuran. SB-657510 inhibited [Ca²⁺]_i mobilization with an IC₅₀ of 180±46 nM, a value consistent with membrane-binding affinity (K_i 61 nM at human UT membranes; Table 1). In contrast, palosuran was significantly (65-fold) less active at inhibiting [Ca²⁺]_i mobilization (IC₅₀ 323±67 nM) as compared to its membrane-binding affinity (K_i 5 nM at human UT membranes; Table 1).