Abstract
1. Although the PRA of substrain B2 was almost the same as that of WK, the PRA of substrain C had significantly low values in comparison with that of them
2. The molecular weights of PR in WK and SHR had almost the same values, but in SHRSP it increased in accordance with elevation in blood pressure
3. Young WK and SHRSP had only small molecular weight renin in the kidneys, but old WK and SHRSP had both big and small ones
4. In kidneys of old SHRSP, the activity of the big molecular weight renin was higher than that of the small one, in contrary of old WK
