Palmitate Stimulates the Epithelial Sodium Channel by Elevating Intracellular Calcium, Reactive Oxygen Species, and Phosphoinositide 3-Kinase Activity

Figure 1

Palmitate increases ENaC activity and elevates intracellular Ca²⁺ levels in A6 cells. (a and c) Representative ENaC single-channel current recorded from A6 cells before and after application of either 0.3 mM palmitate (PA) or 2% BSA to the basolateral bath. (b and d) Summary plots show that palmitate significantly increased ENaC _O ( for each experimental treatment; ), but BSA did not affect ENaC P_O. (e) Left panel shows representative confocal microscopy images of A6 cells, which were loaded with Fluo-3, AM (a Ca²⁺ indicator), before and after application of either palmitate or BSA to the basolateral bath. Right panel shows summary plots of fluorescence intensity of Fluo-3 indicating the levels of intracellular Ca²⁺ ( for each individual experimental treatment; ). Note: in patch-clamp experiments, all the responses had approximately 5 min latency. Therefore, in all the figures, we omitted 5 min recordings after each experimental manipulation.

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