Effects of repeated extracorporeal shock wave in urinary biochemical markers of rats

To access the effect of repeated extracorporeal shock wave (ESW) on urinary biochemical markers

20 rats were assigned for ESW (Direx Tripter X1(R) - 14 KV) to one of two groups: G1 (n=10) one ESW; G2 (n=10) two ESWs within a 14-day interval. Within the twenty-four hour period before and after the application of shock waves, the animals were placed in metabolic cages for 24 hour urine collection. The ph, creatinine, sodium, potassium, chlorides, calcium, magnesium, phosphorus, oxalates, alkaline phosphatase and citrates were measured. Twenty-four hours after the material was collected for urinary determination, the animals underwent nephrectomy of the kidney submitted to the ESW applications and were, then, sacrificed. The kidneys were processed for histopathological examination.

Small variations in the biochemical markers were found in both groups, with no significant differences between the values obtained either prior to or following the ESW applications, except for citrate and alkaline phosphatase. Citraturia decreased significantly in group 2, following the second ESWL application (24.8 +/- 3.0 mg/day after the first ESWL vs. 15.3 +/- 2.2 mg/day after the second ESWL; p < 0.05). Alkaline phosphatase increased significantly following ESWL in group I (0.57 +/- 0.02 vs. 0.79 +/- 0.04 micromol/mg creatinine; p < 0.01) and also in group 2 (0.69 +/- 0.05 vs. 0.83 +/- 0.03 micromol/mg creatinine; p < 0.05). Glomerular, interstitial and sub-capsular hemorrhage with perivascular edema was found in the animals in both groups studied.

A significant increase in urinary alkaline phosphatase was found in both groups studied, suggesting a proximal tubule lesion. In the group of rats undergoing more than one ESWL application, a smaller urinary citrate excretion was noticed, which may be a factor contributing for the formation of new calculi.