P4461Chronic administration of Empagliflozin induces cardioprotection in vivo in absence of diabetes mellitus

Background/Introduction

We have recently shown that empagliflozin (EMPA), a sodium-glucose cotransporter 2 (SGLT2) inhibitor approved for type 2 diabetes mellitus management reduces myocardial infarct size in diabetic mice undergone ischemia/reperfusion (I/R) after chronic administration. However its effect on non-diabetic myocardium remains unspecified.

Purpose

We aimed to investigate: (i) the effect of EMPA on myocardial function and infarct size after I/R in healthy mice, in the absence of diabetes mellitus, (ii) the underlying signaling pathways, (iii) its effects on cell survival in rat embryonic-heart-derived cardiomyoblasts (H9C2) treated with the inhibitor of STAT3, STATTIC.

Methods

C57BL/6 mice were initially randomized into two groups, Control and EMPA (n=7 per group) and treated with 5% DMSO in water for injection and EMPA at a dose of 10mg/kg/day with 5% DMSO in water for injection, respectively, for 6 weeks. After this period, the mice were subjected to 30 minutes of I and 2 hours of R and infarct size was evaluated. Body weight, blood pressure, blood glucose levels and left ventricular shortening measurements by echocardiography, were taken at baseline and at the end of the treatment. Furthermore, in order to assess potential differences in the signaling cascades involved at different time points of reperfusion, additional mice were randomized into Control and EMPA groups which were furtherly subdivided into groups (n=4) of 10' and (n=4) of 120' of reperfusion each. The mice were subjected to I/R and myocardial biopsies were obtained for the assessment of the signaling cascade at the 10th and 120th minutes of reperfusion. H9C2 cells subjected to ischemia–reoxygenation were treated with STATIC (0.5, 1, and 10 μM) during the 3 hours of reoxygenation and evaluated for viability.

Results

Body weight, blood pressure and glucose levels remained unchanged between the groups. We observed no statistically significant change in left ventricular fractional shortening in both groups at baseline (41.0% ± 1.92 vs 40.5% ± 2.7) and after the end of the 6th week (42.7% ± 2.8 vs 40.9% ± 4.1). Infarct size was significantly reduced in EMPA group compared to the Control one (29.5% ± 3.0 vs 45.8% ± 3.2, p<0.05). Phosphorylation of STAT3 was significantly increased at the 10th minute of reperfusion but remained unchanged at the 120th compared to control. The contribution of STAT3 in EMPA-mediated effects was evaluated in H9C2 cells using different doses of STATIC; our results indicate that EMPA completely lost its activity when STAT3 is inhibited. However STATIC per se induces cell death even at low doses.

Conclusion(s)

EMPA reduces infarct size in healthy mice indicating that its cardioprotective effect is independent of the presence of diabetes mellitus. STAT3 activation can be considered as a cardioprotective mechanism of EMPA, however other signaling pathways could be involved in EMPA mechanism of action and are currently under investigation.