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