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. 2020 May 22;152(8):e201912525. doi: 10.1085/jgp.201912525

Figure 7.

Figure 7.

Stimulation of ENaC activity in mCCDcl1 cells by arachidonic acid is mediated via basolateral EP4 receptors and constitutively active COX. The left panel in A and the left and middle panels in B show representative traces of continuous ISC recordings. 50 µM indomethacin (A) or 100 µM AH23848 or 2 µM GW627368X (B; solid lines) was added basolaterally at the time point indicated by an arrow. Dashed lines indicate matched control recordings treated with the respective vehicle (control). About 30 min later cells were exposed to 50 µM apical arachidonic acid and in A followed by basolateral 100 nM PGE2. Finally, apical 10 µM amiloride was added as indicated. Summary data (right panel) are presented as ΔISC values, which were determined by subtracting the corresponding baseline ISC from the ISC reached in the presence (+) or absence (−) of indomethacin, arachidonic acid, PGE2, AH23848, and GW627368X as indicated. The left panels in C and D show representative traces of continuous ISC recordings in which vehicle (control; dashed lines), 50 µM indomethacin, or 2 µM GW627368X (solid lines) was added basolaterally at the time point indicated by an arrow. Approximately 30 min later, medium from the basolateral compartment of a second set of cells (donor cells; not depicted) which were treated with apical 50 µM arachidonic acid was transferred to the basolateral compartment (indicated as medium transfer) in a 1:1 (vol/vol) ratio. This was followed in C by basolateral 100 nM PGE2. Finally, as indicated, 10 µM amiloride was applied to all cells. Summary data (right panel) are presented as ΔISC values, which were determined by subtracting the corresponding baseline ISC from the ISC reached in the presence (+) or absence (−) of indomethacin, GW627368X, PGE2, and medium transfer as indicated. Summary 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 < 0.001; **, P < 0.01; *, P < 0.05, one-way ANOVA with Tukey's multiple comparison test or unpaired Student’s t test, where appropriate.