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DIETARY POTASSIUM SUPPLEMENTATION INCREASES URINE VOLUME AND ALTERS THE CIRCADIAN PATTERN OF SODIUM EXCRETION. POSSIBLE MECHANISM FOR ITS LOWERING EFFECT ON BLOOD PRESSURE
Author(s) -
Perucca Julie,
Bankir Lise
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a510
Subject(s) - natriuresis , endocrinology , excretion , chemistry , medicine , urine , sodium , blood pressure , circadian rhythm , potassium , metabolism , zoology , biology , organic chemistry
Dietary K supplementation (K‐sup) is known to lower blood pressure (BP), but the mechanism remains unclear. An acute K load has been shown to induce an increase in natriuresis, but the influence of a chronic K‐sup on solute excretion has not been evaluated. We investigated the effects of a chronic moderate dietary K‐sup (from 0.75 to 1.65 % weight of the diet) on urine flow rate (V) and Na excretion (NaEx) in conscious rats adapted to metabolic cages. Urine was collected during the active (A, 9 am – 5 pm) and rest (R, 5 pm – 9 am) periods separately, for 2 basal days (normal diet) and during days 1 and 2, and days 6 and 7 of K‐sup when rats had reached a new steady state. Selective K‐sup doubled V during A (p < 0.001) with no change during R. Whole 24 h NaEx was unchanged but NaEx was increased during A (p < 0.001) and decreased during R (p = 0.065) so that the A/R ratio of NaEx was increased from 1.50 ± 0.17 to 2.37 ± 0.19 (p = 0.005). These changes were already apparent on the first day after K‐sup. No change was observed in a control group. These results suggest a novel mechanism for the beneficial effects of K on BP. By increasing V selectively during A, K accelerates NaEx and thus shortens body fluid volume expansion during A and limits the diurnal rise in BP. The beneficial effects of K on BP could thus be analogous to that of diuretics. The factors responsible for the increase in diuresis and the accelerated natriuresis during K‐sup remain to be determined.