Immunoassay for renin: measurement of renal renin content in autopsied hypertensive patients.

Abstract

Immunoassay for renin in human kidneys was undertaken by a hem-agglutination inhibition technique using high titer antirenin produced in rabbits. Human renin, highly purified by DEAE-cellulose and CM-sephadex column chromatography, was used for sensitization of sheep blood cells. Renin was extracted from kidneys of 11 normotensive and 27 hypertensive subjects through the five steps of the purification procedure described by Haas et al. The inhibition titer of antirenin was found to have a linear relationship with the concentrations of renin. However, in assay of lower concentrations of renin, such as plasma renin, there was some difficulty in reading the end-point of reactions since much diluted antirenin serum had to be used. The pressor effect of renin on unanesthetized dogs estimated by the direct method was compared with the results obtained by the hemagglutination inhibition method. Excellent agreement was obtained between results by both methods. The limits of estimation were 0.05 (Goldblatt) unit per gram of kidney tissue for dog assay and 0.001 unit per gram for the hemagglutination inhibition method. The mean value of renin for normal kidney was 0.105±0.033 U/g. The renin content was slightly higher in essential hypertension (0.222±0.066), greatly elevated in malignant hyperten-sion (0.560±0.376), and low in hypertension caused by chronic glomerulonephritis (0.054±0.020), chronic pyelonephritis (0.040), polycystic kidney (0.006), and Cushing's syndrome (0.008).