Published in:
Open Access 01-03-2017 | Short Communication
Empagliflozin decreases myocardial cytoplasmic Na+ through inhibition of the cardiac Na+/H+ exchanger in rats and rabbits
Published in: Diabetologia | Issue 3/2017
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Aims/hypothesis
Empagliflozin (EMPA), an inhibitor of the renal sodium–glucose cotransporter (SGLT) 2, reduces the risk of cardiovascular death in patients with type 2 diabetes. The underlying mechanism of this effect is unknown. Elevated cardiac cytoplasmic Na+ ([Na+]c) and Ca2+ ([Ca2+]c) concentrations and decreased mitochondrial Ca2+ concentration ([Ca2+]m) are drivers of heart failure and cardiac death. We therefore hypothesised that EMPA would directly modify [Na+]c, [Ca2+]c and [Ca2+]m in cardiomyocytes.
Methods
[Na+]c, [Ca2+]c, [Ca 2+]m and Na+/H+ exchanger (NHE) activity were measured fluorometrically in isolated ventricular myocytes from rabbits and rats.
Results
An increase in extracellular glucose, from 5.5 mmol/l to 11 mmol/l, resulted in increased [Na+]c and [Ca2+]c levels. EMPA treatment directly inhibited NHE flux, caused a reduction in [Na+]c and [Ca2+]c and increased [Ca2+]m. After pretreatment with the NHE inhibitor, Cariporide, these effects of EMPA were strongly reduced. EMPA also affected [Na+]c and NHE flux in the absence of extracellular glucose.
Conclusions/interpretation
The glucose lowering kidney-targeted agent, EMPA, demonstrates direct cardiac effects by lowering myocardial [Na+]c and [Ca2+]c and enhancing [Ca2+]m, through impairment of myocardial NHE flux, independent of SGLT2 activity.