The role of the renal kallikrein-kinin system in sodium metabolism in normal and low renin essential hypertension.

In order to investigate the pathophysiological role of the renal kallikrein-kinin system in renin subgroups of essential hypertension, the quantity and activity of urinary kallikrein, urinary kinin excretion, and correlations of kallikrein and kinin excretions with renal sodium handling in the renal tubules were studied in 17 normal subjects, 23 patients with normal renin and 12 patients with low renin essential hypertension. Urine samples were collected by the 2-hour clearance method in the early morning. The quantity and activity of urinary kallikrein, and the urinary excretion of kinin were significantly lower in both low and normal renin patients than in normal subjects. Comparing the normal renin and the low renin group, no significant difference was found in the quantity of urinary kallikrein, while the activity of urinary kallikrein and urinary kinin excretion were significantly lower in low renin patients than in normal renin ones. Fractional excretions of sodium (FENa) and inorganic phosphorus (FEP), which reflect renal tubular and proximal tubular sodium reabsorption, respectively, were significantly lower in the low renin patients than in the normal renin ones. A significantly positive correlation was observed between the urinary kallikrein activity or urinary kinin excretion and FENa or FEP in both normal subjects and normal renin patients, but not in low renin patients.(ABSTRACT TRUNCATED AT 250 WORDS)