Morphometric investigations on intrarenal vessels of streptozotocin-diabetic rats

Abstract

We have investigated 975 different grazing sections of vessels in kidney preparations of 20 rats of the Wistar strain. Half of these genetically identical animals had an insulin-deficiency diabetes induced by injection of streptozocin. The kidneys were removed for investigation after 2 and 12 weeks duration of diabetes. The vessel cross-section, wall, lumen and endothelial surface area were determined in renal arteries, arterioles and preglomerular afferent arterioles in a blind experiment. Statistically detecteable changes were found in the diabetic vessels in the early stage of the diabetes. Preglomerular afferent arterioles showed a highly significant and increasing lumen dilatation commencing after 2 weeks. Diabetic arteries and arterioles developed narrower lumina. A significant thickening of the endothelium took place at the same time in both vessel types. All three vessel regions became smaller and had thinner walls than healthy vessels as the diabetes progressed. The findings on the afferent vessels indicate that haemodynamic effects on the glomerulus are to be expected. Familial diabetic gloermulopathy begins with a reversible hyperfiltration. However, the mechanism has not been clarified in the context of the diabetic metabolic disorder, and this change is probably the haemodynamic consequence of the substantial dilatation of the preglomerular afferent arterioles. With their renin-positive segment, these arterioles are the centre of intrarenal regulation. The increase of the capillary glomerular pressure associated with the dilatation of the preglomerular afferent arterioles is a crucial factor in the development of diabetic glomerulopathy.

Promoting Effects of the Adipokine, Apelin, on Diabetic Nephropathy

“…Histological changes to blood vessels in glomeruli are found in patients with type 1 or 2 diabetic nephropathy [27]–[29]. Swollen endothelial cells and thin walls in the basement membrane of abnormal vessels in diabetics have been observed, suggesting that they are structurally immature [29]–[31]. Abnormal vessels are associated with increased glomerular hypertrophy and enhanced frequency of glomerular occlusion, fibrinoid lesions, tubulointerstitial injury, and urinary albumin excretion [28], [32], [33].…”

The Renal Endothelium in Diabetic Nephropathy

“…62 Interestingly, neovessels are immature with thin basement membrane and endothelial swelling and possibly unable to preserve permselectivity, contributing to microalbuminuria. [62][63][64][65][66] However, the initial increase of GFR progressively declines in diabetic nephropathy. This could be the result of glomerular capillary rarefaction, which characterizes advanced nephropathy.…”

Abnormal Angiogenesis in Diabetic Nephropathy

“…Intriguingly, in this study the abnormal vessels anastomosed to the lobular structure of the intraglomerular capillary network, mainly to afferent branches through the widened vascular hilus, while the distal end of the vessels connected to the peritubular capillary. In these vessels, native endothelial cell function was likely impaired, with the endothelial cells initially swollen and endothelial thickness gradually decreasing as diabetes progressed (9,10). It was also documented that the vascular wall was thickened, owing to an accumulation of matrix in these arterioles (10).…”

“…The abnormal additional vessels found in diabetes possess a thin wall at the basement membrane, while endothelial cells are swollen, suggesting that they are structurally immature and capable of causing an increase in vascular permeability (4,9,19). An increase in capillary permeability often results in the extravasation of plasma protein as well as the forming of lesions in diabetic nephropathy.…”