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., Brooks, H.L., X, J. and Ganong, W.F. (2019). Ganong’s review of medical physiology. 26th ed. New York: Mcgraw-Hill Education