Correlation between expression of 1 α -hydroxylase and hypocalcaemia in rats with severe pancreatitis

To investigate the essential biochemical indices like 1 -hydroxylase and hypocalcaemia in the rats with severe acute pancreatitis and explore the correlation between them.

A total of 120 SPF grade Wistar male rats which were in similar physiological status were selected and randomly divided into two groups: sham group (SO group) and severe acute pancreatitis group (SAP group). Then they were divided into 1 h, 3 h, 6 h, and 12 h subgroups according to the killing time. The severe acute pancreatitis model was established by retrograde injection of 5% sodium taurocholate. Serum calcium, serum creatinine, serum urea nitrogen and serum amylase were measured at different time. Serum 1, 25 dihydroxy vitamin D3 level was determined by enzyme linked immunosorbentassay. The expression of 1-hydroxylase protein in the kidney tissue was determined with Western blotting and immunohistochemistry to observe its location. The pathologic features of the kidney tissue section was observed under light microscope and submicroscopic structure of the proximal convoluted tubule epithelial cell was observed under transmission electron microscope.

Compared with the SO group, rats in the SAP group showed continuous pathological injury as time went by. There was significant increase in serum creatinine, serum urea nitrogen and serum amylase in SAP group compared with the SO group 1, 3, 6, 12 hours after the operation (P<0.05). There was significant decrease in serum calcium and 1, 25 dihydroxy vitamin D3 3, 6, 12 hours after the operation (P<0.05). It also showed that the expression of the 1-hydroxylase protein in kidney tissues was upregulated at 1 h, 3 h and decreased at 6 h, 12 h compared with the SO group. The serum calcium, 1, 25 dihydroxy vitamin D3 and the expression of the 1-hydroxylase protein in kidney tissues of the SAP group showed sustaining decrease. Western blotting showed positive correlation between the 1-hydroxylase expression and serum calcium at 3 h, 6 h and 12 h (r=0.976, P<0.001; r=0.948, P<0.001; r=0.742, P=0.001) and also positive correlation between the 1-hydroxylase expression and serum 1, 25 dihydroxy vitamin D3 at 1 h, 3 h, 6 h and 12 h (r=0.935, P<0.001; r=0.952, P<0.001; r=0.917, P<0.001; r=0.874, P<0.001).

At the early stage of the kidney injury, the expression of 1-hydroxylase in the kidney tissue is reduced with the progress of the disease and the decrease in its activity has a correlation with the hypocalcaemia.