Contractile responses to 5-carboxamidotryptamine (5-CT) (A), angiotensin II (Ang II) (B), and endothelin-1 (ET-1) (C) in human cerebral arteries. Effect of organ culture in the presence of vehicle (n = 5 to 6) and in the presence of SB-590885 (n = 6 to 7) and SB-386023 (n = 6 to 7) are illustrated. The receptor-mediated contractions are clearly reduced by SB-590885. Data are expressed as mean ± s.e.m. ET-1 biphasic concentration-response curve: high-affinity phase refers to the endothelin type B (ETB) receptor-mediated contraction; low-affinity phase refers to the endothelin type A (ETA) receptor-mediated contraction. Statistical analyses are shown for the Emax values where *P < 0.05 and ***P < 0.001 compared with vehicle. Emax values and pEC50 values for respective concentration-response curves are presented in Table 1.