Figure 3.

Effects of TORIN1 and PP242 upon the electrometric response to insulin. In this and in all subsequent such figures the values of equivalent short circuit current (I_Eq) measured during the initial 5 min of each recording period (i.e. the basal I_Eq) has been subtracted from all subsequently measured data points so that each presented trace shows the changes (mean ± SEM, n = 5) from this basal value (ΔI_Eq). (A) Values of I_Eq derived from unstimulated and insulin-stimulated (Ins.; 20 nM, basolateral, arrows) control cells. In this series of experiments the values of basal I_Eq quantified in the unstimulated (Unstim.) and insulin-stimulated cells were −14.4 ± 1.9 µA·cm⁻² and −17.0 ± 2.0 µA·cm⁻² respectively. (B) Data from age-matched cells pretreated (30 min) with 0.1 µM TORIN1 (basal I_Eq unstimulated cells: −13.6 ± 1.2 µA·cm⁻²; basal I_Eq insulin-stimulated cells: −14.6 ± 1.4 µA·cm⁻²). (C) Responses to insulin in control (Con.) and TORIN1-treated cells were quantified by measuring the change in I_Eq that developed during exposure to hormone and subtracting the spontaneous change measured in unstimulated cells. (D) Data showing the spontaneous and insulin-induced changes in I_Eq in control cells (basal I_Eq unstimulated cells: −17.5 ± 1.0 µA·cm⁻²; basal I_Eq insulin-stimulated cells: −20.1 ± 1.6 µA·cm⁻²). (E) Data from age-matched cells pretreated (30 min) with 1 µM PP242 (basal I_Eq unstimulated cells: −13.9 ± 1.1 µA·cm⁻²; basal I_Eq insulin-stimulated cells: −15.7 ± 1.3 µA·cm⁻²). (F) Responses to insulin measured in control and PP242-treated cells. **P < 0.01; ***P < 0.005, significant responses to insulin; Student's paired t-test.