Studies on Renin
I. PURIFICATION OF DOG RENIN AND MICROMETHOD FOR THE DETERMINATION OF RENIN IN DOG SERUM AND TISSUES
Dog renin was produced with a yield of 1.1 Goldblatt units (GU)/g renal tissue and with a specific activity of 1.3 GU/mg protein, i.e., a specific activity 10-16 times higher than that of previous preparations. This renin, free of angiotensinase and of anaphylactoid substances, was used to study the effects of prolonged infusion of renin in normal conscious dogs and as a standard for the bioassay of renin. A simplified method was designed for the indirect assay of canine renin. After prolonged incubation, the angiotensin produced was determined by bioassay in the rat, and the final estimate was expressed as the concentration of renin, in terms of GU, with an accuracy of ± 12.8%. The lower sensitivity of the assay is 1.0 x 10-5 GU/ml; this limit permits an estimate of the endogenous renin in 0.1 ml of normal dog serum or in 0.005 mg of normal canine renal tissue. The sensitivity of this bioassay is, therefore, within the range found in seven radioimmunoassays (0.26 x 10-5 GU/ml to 6.2 x 10-5 GU/ml), and compared with the previous direct bioassay of renin in the dog the sensitivity is approximately 100,000-fold greater. By reference to an internationally accepted unit of renin, the Goldblatt unit, it was possible to recalculate and compare directly the results obtained in seven laboratories on the concentration of renin in blood, renal lymph, and various other tissues. This unified method for the evaluation of renin assays has made possible the determination of the rate of release of renin from the kidneys and the minimum rate of infusion of renin capable of producing persistent appreciable elevation of blood pressure.
- Received August 26, 1971.
- Accepted April 24, 1972.
- © 1972 American Heart Association, Inc.