Fig. 12.

Effects of PD98059 on ENaC-mediated Na⁺ reabsorption (benzamil-sensitive I_sc) and ENaC activity (benzamil-sensitive G_t). Pretreatment with PD98059 under isotonic conditions increased ENaC mRNA expression but not Na⁺ reabsorption. After A6 monolayers were pretreated with 0.1% DMSO or 50 μM PD98059 for 20–24 h in an isotonic culture medium, A6 monolayers were mounted in modified Ussing chambers with 120 mM NaCl (Iso) solution without inhibitors. Then, the extracellular solution was changed from an isotonic to a hypotonic (60 mM NaCl) one without any inhibitors at time 0. A: time course of I_sc. B: benzamil-sensitive I_sc and G_t. After incubation for 120 min, 10 μM benzamil was applied to the apical side and incubated for 10 min for measurement of benzamil-sensitive I_sc and G. Values are means ± SE; n = 4. *P < 0.05.