PS-BPB06-1: GLOMERULAR HEMODYNAMIC CHANGES WITH SGLT2 INHIBITION IN TYPE 2 DIABETIC RATS USING IN VIVO IMAGING

Abstract

Background and aim: Clinical trials have shown that sodium-glucose co-transporter 2 inhibitor (SGLT2i) not only reduce the risk of heart failure and cardiovascular events in people with type 2 diabetes, but also inhibit DKD progression. Improvement of glomerular hyperfiltration via tubuloglomerular feedback (TGF) is considered to be one of the possible pathways for renal protection with SGLT2i in DKD. However, the mechanisms responsible for kidney protection, especially in the setting of T2D, remain incompletely understood. In previous work, we established a method for measuring single nephron GFR (SNGFR) in mice using in vivo imaging and found that the adenosine/adenosine A1 receptor (A1aR) pathway is central for tubuloglomerular feedback (TGF) signaling and the pathogenesis of glomerular hyperfiltration in animal models of type 1 diabetes (Kidokoro K. et al. Circulation 2019). The mechanism of development of glomerular hyperfiltration, and improvement of glomerular hyperfiltration by SGLT2i may, however, be different in type 1 vs type 2 diabetes and related DKD. However, the detailed regulatory mechanism of GFR have not yet been elucidated in DKD related to T2D. Methods: Zucker lean (ZL) rats and Zucker diabetic fatty (ZDF) rats were used. In the first experiment, SNGFR and diameters of glomerular afferent/efferent arterioles were measured in both groups. Next, we examined the change of SNGFR and diameters of glomerular afferent/efferent arterioles, as well as urinary excretions of glucose and sodium in ZDF after a single-dose administration of SGLT2i (luseogliflozin; 10 mg/kg, gavage) for 120 minutes, which generated the following three groups: SGLT2i group, SGLT2i + adenosine A1 receptor (A1aR) antagonist (8-cyclopentyl-1,3-dipropylxanthine, 1 mg/kg) group, and insulin group. Results: SNGFR, afferent and efferent arteriole diameter were significantly increased in ZDF compared to ZL, with greater afferent vs. efferent dilatation. SGLT2i treatment resulted in correction of afferent arteriole vasodilation, with post-SGLT2i diameter that was comparable to baseline levels (p > 0.05). Post-SGLT2i SNGFR was also similar compared to baseline levels. Changes in efferent arteriole diameter were not significant. The inhibitory effect on hyperfiltration by SGLT2i was abolished by the concomitant use of an A1aR antagonist. In contrast, urinary sodium and urinary glucose in SGLT2 inhibitor group increased significantly regardless of adenosine A1 receptor antagonist use. In response to SGLT2i, urinary adenosine and PGE2 increased significantly (p > 0.05), while urine NOx did not change. Conclusion: Regulation of afferent arteriolar tone with SGLT2i is dependent on adenosine/ A1aR signaling an experimental model of T2D related hyperfiltration, regardless of ARB use.