Abstract: Objective To explore the effects of renal artery calcification on the renal function in type 2 diabetic nephropathy rats. Methods Rats were randomly divided into control group(CON group), diabetic nephropathy group (DN group)and DN with vascular calcification group (DN+VC group). Rats of group DN and DN+VC were were fed with high sugar and fat diet and injected with streptozotocin（STZ）into abdominal cavity to induce a model of type 2 diabetes. After diabetic models were successfully made, rats of group DN+VC were treated by vitamin D3 plus nicotine. The rats were sacrificed at 8, 12 and16 week respectively and the pathologic change to the renal artery were detected by von Kossa staining. The calcium content were detected by calcium assay kit and double immunofluorescence staining and real-time polymerase chain reaction (RT-qPCR) were applied to detect the protein and gene expression levels of BMP2 in the renal artery. Measure the levels of blood urea nitrogen (BUN),serum creatinine (Scr),cystatin C(Cys C) and 24 hour urinary protein (24-h UA)respectively at the 8th,12th and 16th weeks. Histopathology of kidney was assessed by hematoxylin/eosin staining . Results The deposition of black granules, the calcium content and the protein and gene expression levels of BMP2 in DN group were significantly higher than those in group CON and lower than DN+VC group at each time points（P<0.05）. The BUN, Scr, Cys C and 24-h UA in group DN and group DN+VC were gradually increased in 8th,12th and 16th weeks, and were higher than those in group CON（P<0.05）. Compared with the DN group, only the level of Cys C at each time point and the level of 24-h UA in 16th week in DN+VC group were significantly higher（P<0.05）. The pathological damages of the kidney in group DN showed a continual worsening trend and the pathological changes of the kidney in group DN+VC were more serious than group DN. Calcium content was positively correlated with the increased serum BUN, Scr, Cys C, 24- h UA and BMP2 mRNA (all P< 0.01). Conclusion The occurrence and severity of renal artery calcification may participate in and promote the progression of DN.

Key words: Vascular calcification, Diabetic nephropathy, Renal artery, Bone Morphogenetic Protein 2