The Study Of Renal Tubular Apoptosis Of Rats With Hyperoxaluria And Ureteral Obstruction

Objectives To investigate the role of hyperoxaluria in the development of renal tubular apoptosis and tubular oxalate crystal deposition in rats; the role of unilateral ureteral obstruction in the development of renal tubular apoptosis ; the role of hyperoxaluria and unilateral ureteral obstruction in the development of renal tubular apoptosis and tubular oxalate crystal deposition .Methods Forty male Wistar rats were divided into four groups,with ten rats in each.The groups were named A(control),B(hyperoxaluric),C(obstuctive)and D (hyperoxaluric+obstuctive). A and B rats underwent sham operation,while left proximal ureteral ligation was performed on C and D rats. ,After operation,A and C rats were given distilled water, B and D rats were given 1% ethylene glycal (a precursor for oxalates) in the drinking water.The rats were sacrificed 2 weeks after operation;left nephrectomy was then performed.Tissue sections obtained from kidneys were examined under polarizing light microscopy for the presence and the degree of crystal deposition in the tubular lumen.Apoptotic changes in renal tubular cells were examined using the terminal deoxynucleotidyl transferase(TdT)-mediated dUTP in situ nick and labeling (TUNEL)method. Results Oxalate crystal deposition was evident in the renal tubular lumen in group B and D,while no evidence in group A and C.There was a statistically significant difference between A and B or D as well as B and D ( P<0.01) .In relation to apoptotic changes,the mean +SD values of the apoptotic cellcount was 1.1 ±1.1 in A and 31.3 ± 8 in B.The value for C and D were 145 ± 33.4 and 275.8 ± 51 respectively.We found a statistically significant difference between all groups (P<0.001) except between C and D (P<0.01). Conclusions Oxalate crystal deposition in the tubular lumen results from hyperoxaluria which is enhanced by ureteral obstruction; hyperoxaluria with complete ureteral obstrution induces an excessive level of apoptosis ,which is responsible for renal damage ,and that ureteral obstruction is a more important factor for apoptosis then hyperoxaluria .