Heterogeneous Downregulation of Angiotensin II AT1-A and AT1-B Receptors in Arterioles in STZ-Induced Diabetic Rat Kidneys

Zsolt Razga,Jens Randel Nyengaard,Nikolett Bódi,Gabor Kovacs,Petra Talapka

doi:10.1155/2014/947506

Zsolt Razga, Jens Randel Nyengaard + Show 3 more

Open Access

https://doi.org/10.1155/2014/947506

Copy DOI

Abstract

Introduction. The renin granulation of kidney arterioles is enhanced in diabetes despite the fact that the level of angiotensin II in the diabetic kidney is elevated. Therefore, the number of angiotensin II AT1-A and AT1-B receptors in afferent and efferent arteriole's renin-positive and renin-negative smooth muscle cells (SMC) was estimated. Method. Immunohistochemistry at the electron microscopic level was combined with 3D stereological sampling techniques. Results. In diabetes the enhanced downregulation of AT1-B receptors in the renin-positive than in the renin-negative SMCs in both arterioles was resulted: the significant difference in the number of AT1 (AT1-A + AT1-B) receptors between the two types of SMCs in the normal rats was further increased in diabetes and in contrast with the significant difference observed between the afferent and efferent arterioles in the normal animals, there was no such difference in diabetes. Conclusions. The enhanced downregulation of the AT1-B receptors in the renin-negative SMCs in the efferent arterioles demonstrates that the regulation of the glomerular filtration rate by the pre- and postglomerular arterioles is changed in diabetes. The enhanced downregulation of the AT1-B receptors in the renin-positive SMCs in the arterioles may result in an enhanced level of renin granulation in the arterioles.

Highlights

The renin granulation of kidney arterioles is enhanced in diabetes despite the fact that the level of angiotensin II in the diabetic kidney is elevated
The significant difference in the number of AT1 (AT1-A + AT1-B) receptors between the two types of smooth muscle cells (SMC) in the normal rats was further increased in diabetes (Table 3)
The AT1-B receptors were downregulated more in the efferent than in the afferent arterioles (Figures 3(a) and 3(b)); in contrast with the significant difference observed between the afferent and efferent arterioles in the normal animals, there was no such difference in diabetes (Table 4)

Summary

Introduction

The renin granulation of kidney arterioles is enhanced in diabetes despite the fact that the level of angiotensin II in the diabetic kidney is elevated. The number of angiotensin II AT1-A and AT1-B receptors in afferent and efferent arteriole’s renin-positive and renin-negative smooth muscle cells (SMC) was estimated. In diabetes the enhanced downregulation of AT1-B receptors in the renin-positive than in the renin-negative SMCs in both arterioles was resulted: the significant difference in the number of AT1 (AT1-A + AT1-B) receptors between the two types of SMCs in the normal rats was further increased in diabetes and in contrast with the significant difference observed between the afferent and efferent arterioles in the normal animals, there was no such difference in diabetes. The enhanced downregulation of the AT1-B receptors in the renin-negative SMCs in the efferent arterioles demonstrates that the regulation of the glomerular filtration rate by the pre- and postglomerular arterioles is changed in diabetes. There is a significant difference between the afferent and efferent arterioles in the number of AT1-B receptors, which are upregulated on the SMC surface on the efferent arterioles [2]

Methods

Results

Discussion

Conclusion