Figure 1.

Basolateral PGE₂ stimulates amiloride-sensitive I_SC in mCCD_cl1 cells. (A–C) Representative traces of continuous I_SC recordings from mCCD_cl1 cells are shown in the left panels and data from similar experiments are summarized in the corresponding right panels. During the time periods indicated by the open horizontal bar, PGE₂ or vehicle (veh) was present. Apical application of 10 µM amiloride (Ami) is indicated by a black horizontal bar. (A) I_SC recordings with basolateral PGE₂ (bl; 100 nM), apical PGE₂ (ap; 1 µM) or vehicle (control) are represented by a black, gray, or dashed line, respectively. (B) I_SC recordings are shown with basolateral application of PGE₂ (black lines) in concentrations from 0.1–100 nM or with vehicle (dashed line). A nonlinear fit for the I_SC response upon PGE₂ application in concentrations of 10 pM to 10 µM was used to estimate EC₅₀. (C) Basolateral PGE₂ (100 nM) was applied in the absence (control; dashed line) or presence of 10 µM amiloride (black line). Arrow indicates time point of apical addition of amiloride or vehicle (control). In the control PGE₂ recording, apical amiloride (10 µM) was added at the end of the experiment. To summarize data from different experiments as ΔI_SC values, the individual I_SC values were corrected by subtracting the corresponding baseline I_SC value. Gray circles highlight the initial phases of the I_SC responses to PGE₂. Summary data (right panels) are presented as individual data points and/or mean values ± SEM. Numbers of experiments are given in parenthesis. Statistical analysis was determined using one-way ANOVA with Tukey's multiple comparison test or Student’s t test where appropriate; ***, P < 0.001. (D) The initial phases of the responses to basolateral PGE₂ encircled in C are shown enlarged using expanded scales. Arrows indicate the time point of PGE₂ application in the continuous presence (black bar, left panel) or absence (right panel) of amiloride.