Sodium sensitivity in human subjects. Hemodynamic and hormonal correlates.

Abstract

To investigate factors associated with sodium sensitivity, 157 subjects were studied while receiving 10 and 200 mEq sodium diets. Measurements included blood pressure (BP), forearm vascular resistance, plasma renin activity (PRA), and plasma aldosterone. Sodium repletion was associated with a greater than 5% increase in mean BP in 16% of the normotensive subjects and 29% of the borderline hypertensive subjects. Sodium-sensitive subjects were compared with sodium-resistant subjects in both the normotensive (n = 92) and borderline hypertensive (n = 65) groups. Forearm vascular resistance was significantly higher (p less than 0.05) during sodium loading in the sodium-sensitive subgroups of both the normotensive and borderline hypertensive groups (35.8 +/- 29 vs 23.8 +/- 20 [SD] and 37.5 +/- 29 vs 22.5 +/- 14 mm Hg/ml/min/100 g, respectively. Venous capacitance was lower in the sodium-sensitive than in the sodium-resistant borderline hypertensive subjects (0.8 +/- 0.21 vs 1.69 +/- 0.24 ml/100 g). During sodium restriction, PRA was significantly lower (p less than 0.01) in the sodium-sensitive subsets (2.56 +/- 1.6 vs 4.04 +/- 2.6; 2.65 +/- 2.1 vs 3.88 +/- 2.6 ng angiotensin I/ml/hr). Aldosterone was lower (p less than 0.01) during sodium depletion in the sodium-sensitive subsets (17.3 +/- 12 vs 26.3 +/- 16; 18.5 +/- 18 vs 27.9 +/- 17 ng/ml). A significant inverse correlation existed between change in BP with sodium repletion and change in PRA or level of PRA during sodium depletion (p less than 0.003).(ABSTRACT TRUNCATED AT 250 WORDS)