Different Mechanisms for the Increased Enzymatic Activity of Renin in Plasma of Patients with Chronic Renal Failure and Patients Receiving Glucocorticoid Therapy

The in vitro enzymatic activity of renin is increased in plasma of patients with chronic renal failure and patients with glucocorticoid excess. To evaluate mechanisms for increased renin reactivity, measurements of plasma renin reactivity, renin substrate, and concentrations of previously identified inhibitors of renin were compared in normotensive controlsubjects, patients on chronic renal dialysis, and renal allograft recipients on maintenance prednisone therapy. After the addition of exogenous renin, the in vitro rate of angiotensin generation was significantly increased (P < 0.01) in the plasma of dialysis patients (mean ± SE, 60.6 ± 2.9 ng⁄ml-h) and steroidtreated subjects (63.5 ±5.0 ng⁄ml·h) compared to that in control subjects (46.3 ± 4.6 ng⁄ml-h). Renin substrate concentration was increased (P < 0.01) in steroid-treated patients but not in patients with chronic renal failure. In subjects on steroid therapy, there was a significant correlation between renin reactivity and renin substrate (r = 0.55;...