Renal function (blood urea nitrogen (BUN)) of the NZB/WF1 mice after treatment with vehicle or the ethyl acetate (EA) extract of Tripterygium wilfordii Hook F. Serum was collected from the animals for assay of BUN before euthanasia. Dotted lines show the normal range for BUN (17 to 28 mg/dl). Numbers in parentheses indicate the animals examined. The horizontal bars indicate the median values of each group. **p < 0.001, vehicle versus EAlow; ***p < 0.01, vehicle versus EAhigh.