ObJective: To observe histopathological changes in renal arteriolar sclerosis for effect of Compound Calculus Bovis Depressurization Formula (CCBDF) on spontaneous hypertensive rats (SHR). Method: SHR of 14-week was used in the study. The rats were treated with CCBDF through intragastric administration for 8 weeks

then histopathological changes in renal arteriole were investigated. Result: Compared with the model group

blood pressure in treated groups ·kg-1(crude drug powder)and 0.6 g ·kg-1(tablet)] were all reduced significantly(P<0.01); the numbers of SHR renal arteriolar sclerosis were decreased

accounting for 20%

20%

30%

40% of total animal number respectively(model group 80%); the number of vessels diseased(NVD) was reduced; and the extent of lesion was lessened. The pathological grades of the four treated groups was 5

5

7

7 score respectively(model group 20 score).Rank sum test (K-S)showed there was significant difference between treated groups(high and middle doses)and model group(P<0.05). Conclusion: Adult SHR can develop renal arteriolar sclerosis and CCBDF has protective effect on SHR renal arteriolar sclerosis as it reduces their hypertension.