Initial studies showed that incubation of Chinese hamster ovary cells (CHO) with Ang-(1-9) potentiated the release of arachidonic acid by [Hyp 3 Tyr(Me) 8 ]BK, elevated [Ca 2 ]i and also resensitized the B2 receptor desensitized by BK [48] . At the same time, Jackman et al. [54] showed in CHO cells and in human pulmonary endothelial cells that Ang-(1-9) was significantly more active than Ang-(1-7) enhancing the effect of an ACE-resistant bradykinin analogue on the B2 receptor and that Ang-(1-9) also augmented arachidonic acid and NO release by kinin [54] .