Class effects of SGLT2 inhibitors in mouse cardiomyocytes and hearts: inhibition of Na + /H + exchanger, lowering of cytosolic Na + and vasodilation.

Aims/hypothesis: Sodium-glucose cotransporter 2 (SGLT2) inhibitors (SGLT2i) constitute a novel class of glucose-lowering (type 2) kidney-targeted agents. We recently reported that the SGLT2i empagliflozin (EMPA) reduced cardiac cytosolic Na ⁺ ([Na ⁺ ] _c ) and cytosolic Ca ²⁺ ([Ca ²⁺ ] _c ) concentrations through inhibition of Na ⁺ /H ⁺ exchanger (NHE). Here, we examine (1) whether the SGLT2i dapagliflozin (DAPA) and canagliflozin (CANA) also inhibit NHE and reduce [Na ⁺ ] _c ; (2) a structural model for the interaction of SGLT2i to NHE; (3) to what extent SGLT2i affect the haemodynamic and metabolic performance of isolated hearts of healthy mice.
Methods: Cardiac NHE activity and [Na ⁺ ] _c in mouse cardiomyocytes were measured in the presence of clinically relevant concentrations of EMPA (1 μmol/l), DAPA (1 μmol/l), CANA (3 μmol/l) or vehicle. NHE docking simulation studies were applied to explore potential binding sites for SGTL2i. Constant-flow Langendorff-perfused mouse hearts were subjected to SGLT2i for 30 min, and cardiovascular function, O ₂ consumption and energetics (phosphocreatine (PCr)/ATP) were determined.
Results: EMPA, DAPA and CANA inhibited NHE activity (measured through low pH recovery after NH ₄ ⁺ pulse: EMPA 6.69 ± 0.09, DAPA 6.77 ± 0.12 and CANA 6.80 ± 0.18 vs vehicle 7.09 ± 0.09; p < 0.001 for all three comparisons) and reduced [Na ⁺ ] _c (in mmol/l: EMPA 10.0 ± 0.5, DAPA 10.7 ± 0.7 and CANA 11.0 ± 0.9 vs vehicle 12.7 ± 0.7; p < 0.001). Docking studies provided high binding affinity of all three SGLT2i with the extracellular Na ⁺ -binding site of NHE. EMPA and CANA, but not DAPA, induced coronary vasodilation of the intact heart. PCr/ATP remained unaffected.
Conclusions/interpretation: EMPA, DAPA and CANA directly inhibit cardiac NHE flux and reduce [Na ⁺ ] _c , possibly by binding with the Na ⁺ -binding site of NHE-1. Furthermore, EMPA and CANA affect the healthy heart by inducing vasodilation. The [Na ⁺ ] _c -lowering class effect of SGLT2i is a potential approach to combat elevated [Na ⁺ ] _c that is known to occur in heart failure and diabetes.