(a) Effects of various concentrations of ET-1 on arachidonic acid release in vascular smooth muscle cells. The cells were stimulated with increasing concentrations of ET-1 for 5 min. (b) Effects of extracellular Ca2+, BQ123, BQ788, and AACOCF3 on ET-1-induced arachidonic acid release in VSMCs. The cells were pretreated with or without 5 μM BQ123, 5 μM BQ788, or 50 μM AACOCF3 for 30 min and incubated with 10 nM ET-1 for 5 min. Arachidonic acid release was determined as described in Methods. Data presented are the mean±s.e.m. of six determinations, each done in triplicate.