Figure 6.

(A) Effect of DA on PI 3-K activity in the presence of the Ca²⁺-independent phospholipase A₂ inhibitor HELSS. Each bar represents the mean ± SEM of three experiments performed independently and in triplicate. (B) DA and arachidonic acid (AA, 100 nM) stimulate PI 3-K activity, and their effect is blocked by ethoxyresorufin (ETX, 100 nM), a specific inhibitor of the cytochrome P450 monooxygenase pathway. The effect of AA or of its cytochrome P450 monooxygenase metabolite 20-HETE (10 nM) was also determined in the presence or absence of the PKC inhibitor bisindolylmaleimide (Bis, 1 μM). In all protocols the cells were incubated with the different agonists for 2.5 min at 23°C. Each bar represents the mean ± SEM of three separate (triplicate) experiments. ∗∗, p < 0.01 versus corresponding value without inhibitor.