Fig. 1

SI113 blocks the aldosterone-stimulated increase in ENaC-mediated sodium absorption and decreases SGK1 activity in a murine cortical collecting duct (mCCD_cl1) cell line. The tracings in A illustrate the average short circuit current, I_SC, a measure of net transepithelial absorptive sodium flux across confluent monolayers of mCCD_cl1 cells grown on permeable supports, for a number of replicates, n, indicated on the graph. Cultures were mounted in Ussing chambers and the spontaneous potential difference across the monolayer was measured and clamped to zero. The resulting I_SC. was measured as a function of time. At time t = − 10 min all cultures were incubated with 10 nM aldosterone delivered to the basal side. At time t = 0 min, experimental cultures were incubated with 20 µM SI113 bilaterally. At time t = 120 min, 1 µM amiloride, a specific inhibitor of the epithelial sodium channel, ENaC, was added to indicate the amount of I_SC that was due to net sodium flux. B represents change from baseline for I_SC of control and experimental cultures. C shows a representative immunoblot (n = 3 biological replicates, technical triplicates) for p-NDRG1 in vehicle treated (DMSO), aldosterone treated (2 h incubation), or SI113 + aldosterone treated cell lysates. Bar charts show relative abundance of p-NDRG1 to total protein in cell lysates. Data represented as mean ± sem in all graphs. I_SC = short circuited current; n = number of replicates; Aldo = aldosterone; SI = SI113; p-NDRG1 = N-Myc Downstream Regulated 1