Salt-induced increases in systolic blood pressure affect renal hemodynamics and proteinuria.
Nine white and 13 black hypertensive patients with normal serum creatinine were randomized to receive either 2 weeks of a low-salt (40 mEq Na+/d) or high-salt (200 mEq Na+/d) diet followed by 2 weeks of the other diet separated by a 1-week washout on their regular diet. The entire study was conducted in an outpatient setting with intensive dietary instruction and monitoring of blood pressure and 24-hour collections of urine for analysis. Urine electrolyte measurement showed that the patients were able to achieve only a modestly reduced (100 +/- 14 mEq Na+/24 h [mean +/- SEM]) low-salt diet as outpatients, while the higher-salt diet (236 +/- 22 mEq Na+/24 h) was more easily achieved. Eleven patients (8 black, 3 white) were classified as modestly salt sensitive on the basis of an increase or decrease in mean arterial pressure of > or = 3 mm Hg going from lower- to high- or high- to lower-salt diets, respectively. In the salt-sensitive patients, the increase in dietary salt intake increased glomerular filtration rate by 29% (71.2 +/- 6.6 to 85.8 +/- 7.3 mL.min-1.1.73 m2, P = .05), with no significant change in renal plasma flow (412.7 +/- 36.4 to 399.6 +/- 27.8 mL.min-1.1.73 m2). There were no changes in these parameters in the salt-resistant patients.(ABSTRACT TRUNCATED AT 250 WORDS)
Weir
M R
MR
Division of Nephrology, University of Maryland School of Medicine, Baltimore, USA.
Dengel
D R
DR
Behrens
M T
MT
Goldberg
A P
AP
D001794:Blood Pressure / Q000187:drug effects*; D018592:Cross-Over Studies; D005260:Female; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D007668:Kidney / Q000187:drug effects* / Q000502:physiology; D008297:Male; D008875:Middle Aged; D011507:Proteinuria / Q000139:chemically induced*; D016037:Single-Blind Method; D012965:Sodium Chloride / Q000494:pharmacology*
D012965:Sodium Chloride