Hyperfiltration can be detected by transcutaneous assessment of glomerular filtration rate in diabetic obese mice

We addressed if hyperfiltration can be assessed transcutaneously in male diabetic obese mice (BTBR^ob/ob) at 12 and 24 wk and how this relates to glomerular parameters indicative for hyperfiltration. Transcutaneous assessment of FITC-Sinistrin clearance [transcutaneous assessment of glomerular filtration rate (tGFR)] was compared against classical plasma clearance. Kidney from SV620C-01-PEI perfused mice were harvested at 24 wk and processed for tissue clearing and classical histology. Perfusion patterns of glomerular capillaries, glomerular size, and vasodilation of the afferent arterioles were assessed. Although at 12 wk FITC-Sinistrin half-life (t_1/2) for both tGFR and plasma clearance suggested hyperfiltration, this was not significant anymore at 24 wk. In kidneys of diabetic mice the diameter of the afferent arteriole was significantly larger and positively correlated with glomerular size. Glomerular perfusion pattern in these mice was heterogeneous ranging from non- to well-perfused glomeruli. Nonperfused glomerular areas displayed a strong periodic acid-Schiff's (PAS) positive staining. Collectively our data demonstrate that tGFR is a valid method to detect hyperfiltration. Hyperfiltration occurs early in BTBR^ob/ob mice and disappears with disease progression as a consequence of a reduced filtration surface. It remains to be assessed if tGFR is also a valid method in diabetic mice with severely compromised renal function.NEW & NOTEWORTHY tGFR measurement is a relatively new method to assess kidney function in conscious rodents, which can be repeated multiple times in the same animal to track the course of the disease and/or the effect of potential treatments. Since the literature was inconclusive on the suitability of this technique in obese mice, we validated it for the first time against classical plasma clearance in the commonly used BTBR^ob/ob mouse model.