Figure 7. Regulation of the activities of PI3K isoforms by KCl and NA.

(A) Stimulation of PI3K-C2α by KCl and NA. VSM was stimulated by either KCl (60 mM), NA (3 μM) or IM (5 μM) for 5 min. (B) Dependence of NA-induced PI3K-C2α activation on extracellular Ca²⁺. VSM was incubated in either normal Ca²⁺-containing or Ca²⁺-free EGTA (1 mM)-containing buffer for 5 min, and stimulated with NA (3 μM) for 5 min. PI3K-C2α was immunoprecipitated with a specific antibody followed by in vitro PI3K assay. (C) and (D) The effects of KCl and NA respectively on the activities of p110α and p110β. VSM was stimulated with either KCl or NA for 5 min and analysed for PI3K activity as in (A). ns, no statistical significance.