RENAL-POTASSIUM & ACID BASE BALANCE

SUMMARY

PROXIMAL TUBULE
1. Na⁺/H⁺ counter-transporter is affected by the potassium concentration.

2. Hypokalemia: stimulates H⁺ secretion (anion ‘substitution’) & stimulates bicarb reabsorption => alkalosis.

3. Hyperkalemia: inhibits H⁺ secretion & inhibits bicarb reabsorption => acidosis.


DISTAL TUBULE
4. Aldosterone enhances distal sodium reabsorption by activating distal tubular Na⁺/H⁺ and Na⁺/K⁺ pumps at the expense of H⁺ loss (alkalosis) and K⁺ loss (hypokalemia).

INTRACELLULAR
5. In alkalemia, K⁺ shifts from the extracellular space to the intracellular space in exchange for H⁺, exacerbating hypokalemia.

Reference(s)

Barrett, K.E., Barman, S.M., Boitano, S., Brooks, H.L., Weitz, M., Brian Patrick Kearns, Ganong, W.F. and Mcgraw-Hill Education (Firm (2016). Ganong’s review of medical physiology. 25th ed. New York: Mcgraw Hill Education.
Hall, J.E. and Hall, M.E. (2020). Guyton And Hall Textbook Of Medical Physiology. 14th ed. S.L.: Elsevier - Health Science.
West, J.B. and Luks, A.M. (2021). West’s Pulmonary Pathophysiology. Lippincott Williams & Wilkins.