The Renal Humoralpressor Mechanism in Man . I . Preparation

Human renin is prepared by a modification of the method of Katz and Goldblatt (1). Human kidneys are obtained as fresh as possible from autopsied cases. Fatty and fibrous parts are discarded and the remainder ground to a pulp in a flour mill. Two volumes by weight of tap water are added, together with toluol as a preservative, and after thorough stirring, the mixture is stored at a temperature of 50 C. overnight or longer. It is strained through 4 thicknesses of cheesecloth and the remaining pulp squeezed through muslin. The pulp is discarded. The filtrate is adjusted to pH 6.0 (glass electrode) and cooled to 5° C. When cool, the filtrate is stirred with a power stirrer, and cold 10 per cent trichloroacetic acid is slowly added under the surface of the solution until the pH is exactly 2.9 0.05 (glass electrode). If filtered at this point, the filtrate is brownish and rich in hypertensinase. A 5.13 molar solution of sodium chloride is therefore added slowly under the surface of the solution with constant stirring until its concentration reaches 0.92 molar. This precipitates the hypertensinase but not the renin. The pH is readjusted at once to exactly 2.90 J 0.05 by the addition of N sodium hydroxide or 10 per cent trichloroacetic acid, and rechecked at the end of 15 minutes. It is then filtered by gravity through fluted filter paper (E & D No. 193) in a cold room at 50 C. The filtrate is clear yellow. Filtration should be complete in 6 hours.