Figure 5.

Effects of TORIN1, PP242 and rapamycin upon the dexamethasone-induced stimulation of Na⁺ transport. (A) Changes in equivalent short circuit current (I_Eq) (n = 6) measured in unstimulated (Unstim.) and dexamethasone-stimulated (Dex.; 0.2 µM, arrows) cells maintained under control conditions (basal I_Eq unstimulated cells: −20.7 ± 1.9 µA·cm⁻²; basal I_Eq dexamethasone-stimulated cells: −22.0 ± 2.8 µA·cm⁻²). (B) Data from age-matched cells at identical passage pretreated (30 min) with 0.1 µM TORIN1 (basal I_Eq unstimulated cells: −15.9 ± 1.8 µA·cm⁻²; basal I_Eq dexamethasone-stimulated cells: −18.9 ± 2.2 µA·cm⁻²). (C) Responses to dexamethasone in control and TORIN1-treated cells were quantified by measuring the change in current that developed during exposure to this hormone and subtracting the spontaneously developing change in I_Eq measured in unstimulated cells. (D) Data (n = 6) from separate experiments showing spontaneous and dexamethasone-induced changes in I_Eq in control cells (basal I_Eq unstimulated cells: −20.8 ± 1.0 µA·cm⁻²; basal I_Eq dexamethasone-stimulated cells: −20.8 ± 1.5 µA·cm⁻²). (E) Data from age-matched pretreated (30 min) with 1 µM PP242 (basal I_Eq unstimulated cells: −14.8 ± 1.0 µA·cm⁻²; basal I_Eq dexamethasone-stimulated cells: −14.7 ± 1.4 µA·cm⁻²). (F) Responses to dexamethasone quantified in control and PP242-treated cells. (G) Spontaneous and dexamethasone-induced changes in I_Eq measured under control conditions (n = 3) (basal I_Eq unstimulated cells: −18.7 ± 0.2 µA·cm⁻²; basal I_Eq dexamethasone-stimulated cells: −19.2 ± 1.7 µA·cm⁻²). (H) Data from age-matched cells pretreated (30 min) with 0.1 µM rapamycin (Rap.; basal I_Eq unstimulated cells: −14.9 ± 1.0 µA·cm⁻²; basal I_Eq dexamethasone-stimulated cells: −15.4 ± 1.9 µA·cm⁻²). (I) Responses to dexamethasone in control and rapamycin-treated cells. **P < 0.02, ***P < 0.01, significant effects of the inhibitors; Student's paired t-test.