Abstract: Objective  To investigate the  impact of repeated intravenous calcium stimulation on aortic calcification in adenine diet-induced chronic kidney disease (CKD) rats.  Methods  Thirty-two Sprague-Dawley (SD) rats were randomly divided into control and model groups. Baseline serum creatinine, blood urea nitrogen, calcium, and phosphorus levels were measured. The rats were fed either a normal diet or a 0.75% adenine diet for 6 weeks, followed by a standard diet for all. Both control and model groups were further divided into two subgroups, resulting in four groups: control + calcium chloride (Cont+CaCl₂), control + saline (Cont+NaCl), CKD + calcium chloride (CKD+CaCl₂), and CKD + saline (CKD+NaCl), with 8 rats in each group. Tail vein injections of calcium chloride solution (100 mg/kg) or an equal volume of saline were administered every other day for 8 weeks. After the intervention, the rats were sacrificed to measure serum creatinine, blood urea nitrogen, calcium, and phosphorus levels. Aortic calcium content was assessed, and Von Kossa staining was performed to detect calcification. Immunohistochemical staining was employed to observe the distribution and expression of osteogenic differentiation markers, including the transcription factor runt-related transcription factor 2 （Runx2）. Western blotting analysis was used to detect the protein expression of bone morphogenetic protein 2 (BMP-2).   Results  At baseline, there were no statistically significant differences in body weight or biochemical indicators among the groups (P>0.05). At the end of the 14th week, compared to the control group, the model group showed significantly higher serum creatinine and blood urea nitrogen levels, lower serum calcium levels, and higher serum phosphorus levels (P<0.05). There were no statistically significant differences in serum calcium, phosphorus levels, or aortic calcium content between the CKD+CaCl₂ and CKD+NaCl groups (P>0.05). Von Kossa staining revealed no calcification in the aortas of either group. Compared to the control group, the model group showed increased expression of Runx2 and BMP-2 in the aorta. There were no significant differences in the expression of Runx2 and BMP-2 between the CKD+CaCl₂ and CKD+NaCl groups.  Conclusions  Under the conditions of this study, repeated intravenous calcium stimulation did not induce aortic calcification in adenine diet-induced CKD rats and had no significant impact on aortic osteogenic differentiation.

Key words: chronic kidney disease, aortic vessel calcification, osteogenic differentiation, calcium-phosphorus metabolism disorder