1. Renal and cerebral vascular lesions occurred more often and earlier in spontaneously hypertensive rats (SHR) given a high salt diet than in SHR given a normal diet.
2. Kidney renin activity was low during high salt loading; the kidney renin activity of rats with hypertensive renal vascular lesions was moderately elevated. Kidney renin activity or cathepsin D activities were higher in stroke-prone SHR (SHRSP) aged 9 months than in stroke-resistant SHR (SHRSR).
3. β-Glucuronidase, cathepsin D and deoxyribonuclease activities were greater in the kidney of Wistar/Kyoto (WK) rats or SHR when there were hypertensive vascular lesions. These three enzyme activities were also greater in the aorta of SHR aged 13–14 months than in the aorta of WK rats.
4. It was supposed that kidney renin activity and lysosomal enzyme activities were related to hypertensive vascular lesions.