Storage form of renin in the dog kidney.

A large part of renin was revealed to be stored in the remin granules as a soluble but hard to release form. Over 70% of the total renin in the granules could be released when the granules were ruptured by hypo-osmotic shock. Renin release from the isolated granules was limited within 20% of the total renin during incubation at 37C in an isotonic medium. 2. Without mechanical or osmotic shock renin granules were quite stable in a cold isotonic solution. Renin release from the isolated granules was not so much influenced by addition of cations which significantly stimulate renin release in vivo. Some cellular components may be required for the release process of renin from the granules as a mediator. 3. The molecular weight of the stored renin in the granules was shown to be 43,000 which was the regular size. Acidification of the extract of the renin granules altered neither molecular size of renin nor renin activity.