Abstract
Aims/hypothesisSodium–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 Ca2+ ([Ca2+]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.MethodsCardiac 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, O2 consumption and energetics (phosphocreatine (PCr)/ATP) were determined.ResultsEMPA, DAPA and CANA inhibited NHE activity (measured through low pH recovery after NH4+ 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/interpretationEMPA, 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.
Highlights
Sodium–glucose cotransporter 2 (SGLT2) inhibitors (SGLT2i) are a new class of type 2 diabetic agents that control plasma glucose levels by inhibiting reabsorption of glucose and sodium in the proximal tubules of the kidney [1]
SGLT2i can bind to Na+/H+ exchanger (NHE), block NHE activity and reduce [Na+]c in cardiomyocytes We investigated whether SGLT2i exhibited similar effects on NHE by studying intracellular Na+ and pH
[Na+]c was reduced with all three SGLT2i (Fig. 1b) after 10 min
Summary
Sodium–glucose cotransporter 2 (SGLT2) inhibitors (SGLT2i) are a new class of type 2 diabetic agents that control plasma glucose levels by inhibiting reabsorption of glucose and sodium in the proximal tubules of the kidney [1]. Of the several different SGLT2i, empagliflozin (EMPA) and canagliflozin (CANA) have shown cardiovascular benefits in type 2 diabetic individuals, with a remarkable 35% and 32% reduction, respectively, in hospitalisation for heart failure [2, 3]. EMPA lowers cytosolic Na+ ([Na+]c) and cytosolic Ca2+ ([Ca2+]c) concentrations, while increasing mitochondrial Ca2+ concentrations, through inhibition of the myocardial Na+/H+ exchanger (NHE) in isolated rabbit and rat ventricular cardiomyocytes Both increased [Na+]c and upregulated NHE activity have been shown to contribute to heart failure and diabetes [5,6,7,8,9]. We studied whether there were direct cardiac haemodynamic and metabolic effects of these SGLT2i on the healthy intact heart
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
