Kinins in relation to renin activity in renal and inferior caval veins in normal individuals and patients with primary aldosteronism.

Blood kinin concentration and plasma renin activity (PRA) were determined in the renal veins and in the inferior caval vein (ICV) below the level of the renal veins in 9 normal individuals (5 men and 4 women) and 7 patients with primary aldosteronism (3 men and 4 women). PRA in the renal veins and ICV was significantly lower and plasma aldosterone concentration in ICV significantly higher in the patients as compared to the normals. Kinin concentration in the renal veins and ICV did not differ significantly between the patients and the normals (0.31 +/- 0.04 (mean +/- SEM) vs 0.45 +/- 0.03 and 0.27 +/- 0.05 vs 0.45 +/- 0.06 microgram/l, respectively). In the normal individuals kinin concentration and PRA were inversely related in the left renal vein (r = -0.80; P less than 0.02), whereas this relation did not reach statistical significance in the right renal vein (r = -0.60; P less than 0.10). Kinin concentration in both renal veins was positively correlated to kinin concentration in ICV (r = 0.73; P less than 0.05 and r = 0.83; P less than 0.02 for the right and left renal vein, respectively). These results indicate that intrarenal kinin formation and renin release are inversely related in normal subjects. Furthermore, they suggest that one and the same enzyme, possibly renal kallikrein, may be implicated in the kinin formation in the systemic as well as in the renal circulation. Intrarenal kinin formation seems not to be increased in primary aldosteronism.