S-51-4: RENAL DENERVATION IMPROVES FLUID RETENTION BY MODULATING RENAL SGLT2 FUNCTION IN RATS WITH HEART FAILURE

Abstract

Objective: Renal denervation (RDN) has been developed as a neuromodulation therapy for patients with treatment-resistant hypertension. RDN is expected to prevent not only hypertension but also heart failure (HF). Sodium-glucose cotransporter 2 (SGLT2) inhibitors have been shown to ameliorate HF and widely used for HF patients. The present study was conducted to assess the effect of RDN on HF and the interaction between renal sympathetic nerves and SGLT2 function in HF. Design and method: HF was induced by coronary artery ligation in rats. Four weeks after coronary artery ligation surgery, surgical bilateral RDN was performed. Western blot analysis was performed to assess the expression levels of SGLT2. One week after RDN surgery, as a functional test for SGLT2 activation, natriuretic response to intravenous injection of SGLT2 inhibitor dapagliflozin (0.5 mg/kg, i.v.) was investigated. Furthermore, the changes in expression and localization of SGLT2 were assessed in human embryonic kidney cells treated with norepinephrine directly, in vitro. Results: Western blot analysis indicated that renal SGLT2 expression is increased in rats with HF. RDN significantly reduced enhanced renal SGLT2 expression in HF. Natriuretic response to dapagliflozin were greater in HF than Sham (Cumulative sodium excretion at 120 min, 227 ± 35 vs. 133 ± 13 μEq/gkw, P < 0.05, n = 6). RDN significantly attenuated natriuretic response to dapagliflozin in HF (Cumulative sodium excretion at 120 min, 138 ± 19 vs. 227 ± 35 μEq/gkw, P < 0.05, n = 6). Direct application of norepinephrine on human embryonic kidney cells, in vitro, resulted in an increased expression of SGLT2 and specifically promoted the translocation of SGLT2 from the cytosol to the cell surface (Cytosolic SGLT2/GAPDH 0.51 ± 0.05 vs. 0.86 ± 0.08, Membranous SGLT2/Na-K-ATPase 1.06 ± 0.10 vs. 0.54 ± 0.03, P < 0.01, n = 6). Moreover, RDN increased the cytosolic SGLT2 while decreasing membranous SGLT2 in the kidneys of rats with HF (Cytosolic SGLT2/GAPDH 1.30 ± 0.11 vs. 0.58 ± 0.09, Membranous SGLT2/Na-K-ATPase 0.51 ± 0.10 vs. 2.08 ± 0.08, P < 0.01, n = 6). Conclusions: These findings suggest that the excessive activation of renal sympathetic nerves in HF increases the expression of SGLT2 protein trafficked by norepinephrine to cell membrane in proximal tubules resulting in greater sodium retention associated with HF condition. RDN mitigates the enhanced expression and activity of SGLT2 and ameliorates the subsequent sodium and water retention associated with HF, suggesting the potential therapeutic use of RDN for HF.