Canagliflozin inhibits electrogenic Na⁺transport in mouse cortical collecting duct cells

Sodium-glucose cotransporter 2 inhibitors (SGLT2i) were developed as a therapeutic tool to control hyperglycemia in patients with type 2 diabetes. However, these drugs are now widely understood to have cardiorenal protective effects which involve mechanisms aside from SGLT2 inhibition alone. Still, many details surrounding these clinically important “off-target” effects remain unclear. Our group recently showed that several key proximal tubular cell transport functions (e.g., endocytosis, Na + /H + exchange) are inhibited by the SGLT2i, canagliflozin, in an SGLT2-independent and SGK1-dependent manner. We therefore hypothesized that canagliflozin would inhibit epithelial Na + channel (ENaC)-dependent Na + transport in the distal nephron, as this process also requires SGK1. To test this, we performed biochemical and functional experiments using mouse cortical collecting duct (mCCD Cl1 ) cells. Western blot analysis revealed that both canagliflozin and the structurally related empagliflozin acutely reduced SGK1 abundance by 20-30% in mCCD Cl1 cells. However, only canagliflozin inhibited amiloride-sensitive short circuit current (I SC ) (72% vs. vehicle), while empagliflozin did not. This effect occurred within minutes and was concentration dependent (IC 50 ~ 17 μM). To determine whether I SC inhibition occurred via effects on ENaC and/or the Na + /K + ATPase, we used nystatin to selectively permeabilize the basolateral or apical membrane, respectively, in the presence of a transepithelial Na + gradient. We found that canagliflozin significantly reduced both amiloride- (55%) and ouabain-sensitive (90%) currents under these conditions, consistent with a mechanism involving SGK1. Surface labelling experiments further showed that canagliflozin reduced apical membrane γ-ENaC localization by 35% without affecting total protein expression, while neither surface nor total NaKα protein was altered. Together, these studies identify electrogenic distal nephron Na + transport as a novel target of inhibition by canagliflozin. Our data further suggest that the underlying mechanism likely involves SGK1-dependent effects on ENaC surface expression and Na + /K + ATPase activity. F32DK136356, R25HL158295, U54DK137329, R01DK125439 This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.