ET activates PKA in HMVEC-Ls. HMVEC-Ls were seeded onto 10 cm plates and allowed to reach 80-90% confluence prior to (A) 6 h exposure to increasing doses of ET, or (B) increasing exposure times with ET (1000 ng/mL:1000 ng/mL). Lysates were collected and PKA activity assayed by ELISA. Each vertical bar represents mean (+/- SEM) absorbance at 450 nm. The n for each group is indicated in each bar. * indicates significantly increased compared to the simultaneous medium controls at p < 0.05.