Key result
Shifting the timing of sodium ingestion from daytime to nighttime eliminated the diurnal variations in plasma renin activity, plasma aldosterone, and urinary electrolytes.
Why the study?
Does the timing of dietary sodium ingestion affect the diurnal variation of the renin-angiotensin-aldosterone system and urinary electrolyte excretion in normal men?
Does the timing of dietary sodium ingestion affect the diurnal variation of the renin-angiotensin-aldosterone system and urinary electrolyte excretion in normal men?
The diurnal variation of the renin-angiotensin-aldosterone system and urinary electrolyte excretion appears to be driven by the timing of sodium ingestion rather than an intrinsic circadian rhythm.
Altered meal timing may abolish diurnal electrolyte rhythms; leaves open any clinical impact on hypertension or outcomes.
Diurnal variations of five normal men were tested over three 24 h consecutive periods. The first experiment began at 0900 h after the subjects had fasted for 12 h and a normal sodium diet of about 70-80 mEq was given at 0900 h, 1200h, and 1630 h (total of about 220 mEq of Na). Significant variations in the plasma renin activity (PRA), in the plasma aldosterone (PA), and in the urinary Na and K outputs were found. The second experiment began at 1200 h with the first feeding time at 2100 h after fasting about 24 h and the subjects were given a normal sodium diet as in the first experiment, but with the meals given at 2100 h, 2400 h, and 0430 h. The diurnal variations in PRA, plasma aldosterone, and urinary electrolytes disappeared. From this study, it appears that the diurnal variation in urinary electrolyte excretion is a factor of the diurnal variation in PRA and plasma aldosterone. The diurnal variation in PRA and plasma aldosterone are related to the timing of sodium ingestion.
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KUNITA et al. (1976) studied Healthy (n=5). Timing of sodium ingestion vs. Daytime vs nighttime feeding was evaluated on Diurnal variations in plasma renin activity, plasma aldosterone, and urinary electrolytes. Shifting the timing of sodium ingestion from daytime to nighttime eliminated the diurnal variations in plasma renin activity, plasma aldosterone, and urinary electrolytes.
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