Fig. 6.

Effect of osmolarity on endothelin-1 (ET-1) promoter activity (assessed by the ratio of secreted luciferase/secreted alkaline phosphatase) in inner medullary collecting duct 3 cells. In A, cells were transfected with 1-, 2-, or 3-kb ET-1 promoter-reporter constructs and then exposed to 300 or 350 mosM (using mannitol) for varying time periods. In B, cells were transfected with a wild-type 1-kb ET-1 promoter-reporter construct or a 1-kb ET-1 promoter construct in which the two NFAT5 binding sites were mutated and then exposed to 300 or 350 mosM (using mannitol) for 4 h. n = 6–9 for each data point. *P < 0.05 vs. 300 mosM at the same time point; #P < 0.05 vs. wild-type 1-kb promoter at 300 mosM.