OBJECTIVETo investigate the effect of total saponin of dioscorea (TSD) on uric acid excretion indicators in chronic hyperuricemia rats, and to study the correlation between blood levels of uric acid (SUA) and uric acid excretion indicators.

METHODSTotally 90 SD male rats were randomly divided into 6 groups, i.e., the normal group, the model group, the benzbromarone group (10 mg/kg), the high, middle, and low dose TSD group (300,100, 30 mg/kg, respectively), 15 in each group. The chronic hyperuricemia model was prepared by potassium oxonate (200 mg/kg) and ethambutol (250 mg/kg) except in those of the normal group. All rats were intragastrically administered with corresponding medication once daily for 4 successive weeks since the third week. Contents of SUA and urine uric acid (UUA), serum creatinine (SCr), urine creatinine (UCr), blood urea nitrogen (BUN), and urine volume (UV) were measured on day 14 and day 28 respectively. Uric acid excretion indicators [including the amount of 24 h uric acid excretion (24 h UUA), fractional excretion of uric acid (FEUA), uric acid clearance (CUr), creatinine clearance (CCr), excretion of uric acid per volume of glomerular filtration (EurGF), and ratio of urinary uric acid to creatinine (UUA/UCr)] were calculated. The correlation between SUA and uric acid excretion indicators was analyzed by Pearson correlation analysis.

RESULTScontents of SUA and SCr significantly increased, while the UUA, 24 h UUA, CCr, CUr, FEUA, EurGF, and UUA/UCr significantly decreased in the model group on day 14 and day 28. TSD could dose-dependently reduce the SUA level, significantly increase the UUA, 24 h UUA and CCr, Cur, FEUA, EurGF, showing an approximate effect to that of benzbromarone. But it had no effect on BUN, UCr, UUA/UCr, or UV of hyperuricemia rats. Correlation analysis showed that SUA level was positively correlated with SCr on day 14 and day 28 (r = 0.359, r = 0.306), but negatively correlated with CUr, FEUA, and CCr (r = -0.749 and -0.733; r = -0.669 and -0.646; r = -0.359 and -0.273). SUA level was not correlated with EurGF or UUA/UCr (r = 0.134 and 0.078; r = -0.057 and -0. 065). SUA level was negatively correlated with 24 h UUA on day 14 (r = -0.267), but not correlated with UUA or UCr on day 14. SUA level was negatively correlated with UUA and UCr on day 28 (r = -0.269, r = -0.275), but not correlated with 24 h UUA on day 28.

CONCLUSIONSTSD could promote the excretion of uric acid and significantly increase the excretion of uric acid indicators. SUA was positively correlated with SCr, negatively correlated with Cur, FEUA, and CCr. FEUA and CUr were sensitive indicators of renal excretion of uric acid.