Role of renal microcirculation in experimental renovascular disease.
BACKGROUND
Renal artery stenosis (RAS) causes renal injury partly via microvascular (MV) endothelial dysfunction and damage. Vascular endothelial growth factor (VEGF) is crucial for preservation of microvasculature and promotes vascular proliferation and endothelial repair. We have previously shown that MV rarefaction is associated with decreased VEGF in the kidney exposed to chronic RAS, accompanied by deteriorated renal function and fibrosis. We hypothesized that preserving the renal microcirculation in the stenotic kidney will halt the progression of renal damage.


METHODS
Unilateral RAS was induced in 16 pigs. In eight, VEGF (0.05 micrograms/kg) was infused intra-renally at the onset of RAS. After 6 weeks, single-kidney haemodynamics and function were assessed using in vivo multi-detector computed tomography (CT). Renal microvessels, angiogenic pathways and morphology were investigated ex vivo using micro-CT, real-time PCR and histology.


RESULTS
Blood pressure and degree of RAS was similar in RAS and RAS + VEGF pigs. Single-kidney renal blood flow (RBF) and glomerular filtration rate (GFR) were reduced in RAS compared to Normal (221.1 +/- 46.5 and 29.9 +/- 3.8 vs. 522.5 +/- 60.9 and 49.3 +/- 3.4 mL/min, respectively, P < 0.05), accompanied by decreased cortical MV density and increased renal fibrosis. Pre-emptive administration of VEGF preserved MV architecture, attenuated fibrosis and normalized RBF and GFR (510.8 +/- 50.9 and 39.9.1 +/- 4.1 mL/min, P = not significant vs. Normal).


CONCLUSIONS
This study underscores the importance of the renal microcirculation in renovascular disease. Intra-renal administration of VEGF preserved renal MV architecture and function of the stenotic kidney, which in turn preserved renal haemodynamics and function and decreased renal fibrosis. These observations suggest that preventing renal MV loss may be a potential target for therapeutic approaches for patients with chronic renovascular disease.
Iliescu
Radu
R
The Department of Physiology and Biophysics, Center for Excellence in Cardiovascular-Renal Research, University of Mississippi Medical Center, Jackson, MS, USA.
Fernandez
Solana R
SR
Kelsen
Silvia
S
Maric
Christine
C
Chade
Alejandro R
AR
D000818:Animals; D015153:Blotting, Western; D005919:Glomerular Filtration Rate; D006439:Hemodynamics; D007124:Immunoenzyme Techniques; D007668:Kidney / Q000098:blood supply* / Q000378:metabolism / Q000473:pathology; D007677:Kidney Function Tests; D008833:Microcirculation / Q000502:physiology*; D018919:Neovascularization, Physiologic; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012078:Renal Artery Obstruction / Q000503:physiopathology*; D012079:Renal Circulation / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013552:Swine; D042461:Vascular Endothelial Growth Factor A / Q000008:administration & dosage / Q000235:genetics / Q000378:metabolism
D012333:RNA, Messenger; D042461:Vascular Endothelial Growth Factor A