Figure 5.

The stimulatory effect of PGE₂ is similar and not additive to those of vasopressin and forskolin. (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. (A) At the time point indicated by an arrow, cells were exposed to 25 pM basolateral vasopressin (solid line) or vehicle in matched control recordings (control, dashed line). About 20 min later all cells were exposed to 100 nM basolateral PGE₂ and subsequently to apical amiloride (Ami; 10 µM) as indicated. (B) At the time point indicated by an arrow, cells were exposed to 100 nM basolateral PGE₂ (solid line) or vehicle in matched control recordings (control, dashed line). Approximately 20 min later, all cells were exposed to 25 pM basolateral vasopressin and subsequently to apical amiloride (10 µM) as indicated. (C) At the time point indicated by an arrow, cells were exposed to 10 µM forskolin (solid line) to stimulate adenylyl cyclase or to vehicle in matched control recordings (control, dashed line). Approximately 20 min later, all cells were exposed to 100 nM basolateral PGE₂ and subsequently to apical amiloride (10 µM) as indicated. Summary data (right panel) are presented as ΔI_SC values, which were determined by subtracting the corresponding baseline I_SC from the I_SC reached in the presence (+) or absence (−) of PGE₂, vasopressin, and forskolin as indicated. Data are presented as individual values and their mean ± SEM. Paired data are connected by dashed lines. Numbers of experiments are given in parentheses. *, P < 0.05; **, P < 0.01; ***, P < 0.001, paired Student’s t test.