AngII, ROS, and the JNK pathway are involved in leptin expression in HCASMCs under hypoxia. (A and B) Under hypoxia, AngII (10 nM), an ROS generator (Dp44mT; 30 nM)), and a JNK MAPK stimulator (Anisomycin; 20 μM) increased leptin protein expression in HCASMCs. AngII-induced leptin protein expression could be inhibited by SP600125 (25 μM) and NAC (500 μM). Dp44mT-induced leptin protein expression could be inhibited by SP600125 (25 μM). However, Anisomycin-induced leptin protein expression could not be inhibited by losartan (ARB; 100 nM) or NAC (500 μM). These results imply that hypoxia-induced leptin expression in HCASMCs is regulated through the JNK pathway, with its earliest expression coming from treatment with AngII, and then from ROS. *P < 0.01 vs. normoxia control. #P < 0.01 vs. 4 h (n = 3).