Sialorphin activates Hif-1a though a GPCR pathway. A) Representative blot showing protein expression of Hif-1a and A2BR in rat corporal cells treated with sialorphin alone, PTX, or a combination of sialorphin and PTX. B, C) Densitometric analysis of 3 separate experiments to determine expression of Hif-1a, A2BR, and GAPDH. Expression of Hif-1a and A2BR were normalized to the housekeeping gene GAPDH. Data represent mean ± sd fold change in expression of Hif-1a (B) and A2BR (C) normalized to untreated controls are. *P < 0.05 vs controls; vP < 0.05 vs. sialorphin alone. D) Hif-1a luciferase reporter assay. Confluent CSM cells were transiently transfected with a reporter construct in which the Hif-1a promoter drives expression of luciferase. After 24 h, transfected cells were treated with 400 nM sialorphin alone, 200 ng/ml PTX alone, or a combination of sialorphin and PTX for 8 h. Cells were lysed, and luciferase activity was normalized to protein. Results are expressed as fold change in luciferase activity compared to activity in the untreated control. Data are expressed as means ± sd. *P < 0.05 vs. controls; vP < 0.05 vs. sialorphin alone.