Early and late adjustment to potassium loading in humans

Area of Science:

• Nephrology
• Endocrinology
• Human Physiology

Background:

• Dietary potassium (K) intake significantly influences electrolyte balance and hormonal regulation.
• Understanding the human body's adaptation to high K diets is crucial for managing blood pressure and fluid balance.

Purpose of the Study:

• To investigate the physiological adaptations to sustained high potassium (K) loading in healthy humans.
• To characterize the time course of renal K excretion and sodium (Na) balance during K loading and withdrawal.

Main Methods:

• Six healthy human subjects underwent controlled high K loading (400 mmol/day) for 20 days.
• Plasma K, aldosterone, renin activity, and urinary K and Na excretion were monitored throughout the study.
• Acute responses to individual K meals were assessed at different time points.

Main Results:

• High K intake rapidly increased plasma K and aldosterone, leading to increased K excretion (kaliuresis) and transient Na loss.
• K balance was achieved within 48 hours, with enhanced kaliuresis over time.
• Na loss was compensated by day 20, while aldosterone and renin activity returned to baseline, though aldosterone still rose post-meal.
• Discontinuation of K loading caused a brief negative K balance and subsequent Na retention.

Conclusions:

• Switching to a high K diet induces immediate renal K excretion and Na loss, mediated by aldosterone.
• Renal adaptation over days enhances K excretion and prevents sustained Na loss.
• Aldosterone and renal adaptation play key roles in maintaining electrolyte homeostasis during high K intake.