Ultrastructural pathological features of unilateral renal artery stenosis in the rats

Renal artery stenosis (RAS) is one of the main reasons of renovascular hypertension and its pathogenesis remains unclear. In this study, we aimed to investigate histopathological characteristics in a rat model of RAS. Sprague-Dawley (SD) male rats were randomly divided into unilateral RAS group (Model group, n=30) and Sham group (n=30). The left renal artery was clamped with miniature silver clip for the rats in RAS group, while it was exposed but not clamped for the rats in Sham group. After the surgery, the rats were randomly divided into ten subgroups based on the time after surgery (n=3). Blood pressure, urinary albumin/creatinine ratio, and serum albumin and creatinine levels were measured. The kidneys were dissected for histological and electron microscopy analysis. The results showed that systolic blood pressure was significantly higher since 4 weeks after surgery compared to before surgery. There were no significant differences in urinary albumin/creatinine ratio as well as serum albumin and creatinine levels in Model and Sham groups. During the early acute renal ischemia the stenotic kidney exhibited acute tubular injury, podocyte injury and some crescent formation, and the main components of crescent are podocytes. Although renal tubules and vascular lesions gradually recover and crescent disappears, segmental lesions of podocyte appear in the late stage of RAS. These data reveal ultrastructural pathological changes during RAS, and suggest the role of podocyte lesions in chronic renal ischemia.