【Animal Modeling】-Relationship between vascular calcification and bone metabolism markers in rats with chronic kidney disease

  Objective To study the correlation between vascular calcification and serum bone metabolism markers in chronic kidney disease rats.

  Methods Thirty-six male SD rats were randomly divided into control group (18) and CKD vascular calcification group (18). The calcification group was given adenine combined with high phosphorus diet, and the control group was given normal saline and normal diet. Rats were sacrificed at the end of the 2nd, 4th, and 6th week of the experiment, and the aorta was collected for Von Kossa staining and calcium content to detect the degree of calcification. Calcium (Ca), Phosphorus (P), 1,25-Dihydroxyvitamin D3 (1,25(OH)2,D3,), Parathyroid hormone (PTH), Bone-derived alkaline phosphatase (BALP), Osteocalcin (OC), total type I procollagen amino terminal peptide (tPINP), β-1 collagen cross-linked carboxy terminal peptide (β-CTX), tartrate-resistant acid phosphatase-5b (TRACP-5b) and 24 h Urine protein quantification (24 h-Upm).

  Results The Von Kosa staining of the aorta in the control group showed no black matter deposition at each time point, while the CKD vascular calcification group gradually increased the black matter deposition with time. Compared with the control group, the contents of BUNScr, 24 h-Upro and aortic calcium in the CKD vascular calcification group increased (P<0.05); Ca, 1,25(OH), D, PTH, tPINP, β-CTX, TRACP -5b decreased (P<0.05), P, Ca*P increased (P<0.05), oc="" increased="" p="">0.05); binary logistic regression found that serum Ca*P increased, PTH and TRACP- Decreased 5b is an independent risk factor for vascular calcification. According to the degree of aortic calcification, the CKD vascular calcification group was further divided into two subgroups with mild to moderate calcification (2W and 4W) and severe calcification (6W). Compared with the mild and moderate calcification group, the BUN, Scr, and aortic calcium contents in the severe calcification group increased (P<0.05), 24="" and="" the="" h-upro="" increased="" p="">0.05); Ga, P, 1, 25 (OH) , D, PINP, TRACP-5b increased (P>0.05), Ca*P, PTH, BALP, β-CTX increased (P<0.05), OC decreased (P<0.05); Risk factor analysis showed that elevated serum Ca*P and decreased OC were independent risk factors for the severity of vascular calcification. Correlation analysis showed that serum Ca*P, PTH, BALP, β-CTX levels were positively correlated with the degree of vascular calcification, and OC was negatively correlated with the degree of vascular calcification.

  Conclusion Vascular calcification in CKD rats is closely related to bone metabolism. Detection of serum bone metabolism markers is helpful to evaluate the occurrence of vascular calcification and to judge the severity and progression of vascular calcification.