Cardioprotective effects of Empagliflozin in cardiac volume overload-induced by aortocaval fistula in rats

Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Slovak Research and Development Agency under the contract no. 21-0410 VEGA grants no. 2/0006/23 Heart failure is characterized by reduction in cardiac output and the occurrence of malignant arrhythmias, thereby contributing significantly to high morbidity and mortality worldwide. Myocardial structural remodelling is a key factor contributing to the development of these life-threatening events and belongs to unsolved clinical issues challenging to investigate in animal models. The aim of our study was to explore the impact of cardiac volume overload (VO) on structural remodelling and electrical coupling protein, connexin43 (Cx43) in the left and right heart ventricles as well as the efficacy of treatment with SGLT2i, Empagliflozin. Aortocaval fistula (ACF) was surgically induced in 6-month-old Wistar rats, to develop VO during 4 weeks, followed by oral administration of Empagliflozin 10 mg/kg/b.w. daily for 5 weeks. At the end of the experiment, biometric parameters were registered and left and right heart tissue samples were snap-frozen and kept at -80°C for western blot analysis and microscopic examination. Findings revealed an increase of heart, left and right ventricular mass due to ACF-VO versus sham controls, which was associated, with eccentric myocardial hypertrophy. Noteworthy, Empagliflozin reduced heart, left and right ventricular mass. Levels of myocardial protein Cx43, that determine electrical coupling among cardiomyocytes, were reduced by ACF-VO, while normalized by treatment with Empagliflozin. Moreover, treatment attenuated ACF-VO-induced increase of interstitial collagen visualized by van Gieson staining. It was in line with the protein expression of MMP-2, which is involved in structural remodeling. The protein levels of PKCε, concerned/associated with modulation of Cx43 and extracellular matrix, were decreased due to ACV-VO but normalized after treatment with Empagliflozin. On the other hand, protein levels of PKCδ, involved in proapoptotic and prohypertrophic pathways, were increased and normalized by Empagliflozin. The changes were more pronounced in the right ventricle compared to the left heart ventricle. In summary, our pilot results point out the benefit of Empagliflozin due to the suppression of myocardial structural remodelling and preservation of Cx43 in the rat ACF-VO model. Furthermore, this Empagliflozin-induced cardioprotection was associated with the normalization of Cx43, MMP-2, and PKC levels independent of glucose control. However, further analyses are needed to reveal the molecular mechanisms of the cardioprotective effects of Empagliflozin.