Chronic renal denervation prevents glomerular hyperfiltration in diabetic rats

Abstract

Background. The increase in glomerular filtration rate (GFR) induced by amino acid infusion is attenuated in rats with chronic renal denervation. The aim of the present study was to investigate whether renal denervation abrogates glomerular hyperfiltration occurring in the early state of diabetes mellitus. Methods. Sprague-Dawley rats were subjected to bilateral renal denervation before induction of diabetes mellitus (DM) by streptozotocin. Clearance experiments were performed 2 weeks after onset of moderate DM. Glomerular volume was estimated following paraformaldehyde fixation in rat kidney slices from measurement of cross-sectional area of Bowman's capsule. Results. GFR in non-diabetic rats with intact nerves (CON-INN) was 0.82 ± 0.03 ml·min-1·100 g-1 body weight. Diabetic animals with innervated kidneys presented a significant glomerular hyperfiltration (1.13 ± 0.03 ml·min-1·100 g-1 body weight), while renal denervation in diabetic rats lowered GFR towards levels of CON-INN (0.88 ± 0.03 ml·min-1·100 g-1 body weight). Estimated glomerular volume amounted to 0.69 ± 0.03.106 μm3 in the CON-INN group and was significantly higher in diabetic animals with intact renal nerves (0.86 ± 0.04.106 μm3). Interestingly, renal denervation prevented the glomerular enlargement due to DM. Conclusions. Renal nerves appear to be significantly involved in the mediation of glomerular hyperfiltration in experimental DM. If the kidney is prevented from sympathetic nerve stimulation, structural changes due to early diabetic nephropathy, i.e. glomerular enlargement, are abolished.