Objective:To observe the expression of hypoxia-inducible factor 1 alpha (HIF-1α) signaling pathway in the aorta of chronic kidney disease (CKD) rats with vascular calcification and to explore the role of this pathway in aortic calcification of CKD.Methods:Forty 8-week-old male SD rats were randomly divided into control group (CON group, n=15) and CKD with aortic calcification group (CKD+AC group, n=25). The rats were sacrificed at the end of 4 th, 6 th and 8 th week respectively and urine, blood, aorta and kidney samples were collected. The level of serum HIF-1α was tested by ELISA. The pathology changes of kidney were observed by HE staining. The aortic calcification was evaluated by alizarin red staining and calcium content detection. Immunohistochemistry and real-time PCR were applied to detect the protein and mRNA expression of alpha-smooth muscle actin (α-SMA), Runt-related transcription factor 2 (Runx2), HIF-1α, vascular endothelial growth factor A (VEGFA) and Notch1 in the aorta. Results:Compared with CON group, serum urea, creatinine, cystatin C, phosphorus, calcium-phosphorus product and 24-h urine protein were significantly higher in CKD+AC group (all P<0.05). Serum HIF-1α levels were higher at 4 th and 8 th week in CKD+AC group than that in CON group (both P<0.05). There was no significant calcium deposit in the aorta of the CON group at all time points, and calcium deposits were seen in the aorta of the CKD+AC rats at each time point, which gradually increased with time. Compared with CON group, the expressions of aortic α-SMA protein and mRNA were significantly decreased in CKD+AC group at each time point, however the protein and mRNA expressions of Runx2, HIF-1α, VEGFA and Notch1 in the aorta of CKD+AC group rats were markedly increased at each time point (all P<0.05). Correlation analysis showed that the aortic calcium content was positively correlated with serum HIF-1α ( r=0.706, P<0.001) and the protein expressions of HIF-1α ( r=0.852, P<0.001), VEGFA ( r=0.747, P<0.001) and Notch1 ( r=0.813, P<0.001) in aorta. Conclusion:The HIF-1α-VEGFA-Notch1 signaling pathway is activated during aortic calcification in CKD rats, suggesting that this signaling pathway might be involved in the vascular calcification in CKD, and serum HIF-1α is expected to be one of serum markers for CKD vascular calcification.