Kalium (intrazellulär): the pathway in the body

Kalium (intrazellulär) is part of the pathway “Sodium and potassium”. This page shows the whole pathway; the station of Kalium (intrazellulär) is highlighted.

Where this laboratory value sits: Potassium in the cell — plentiful inside. Because of the pumping, almost all of the body’s potassium is inside the cells, above all in muscle cells. Source 1, 2

In brief

Sodium and potassium are charged minerals: sodium dominates outside cells, potassium inside. The sodium-potassium pump maintains this gradient, which carries nerve impulses and the transport of nutrients.

The pathway step by step

1. Sodium and potassium → Uptake in the gut NHE3, channels Sodium enters the gut cells via channels and exchangers such as NHE3; water follows it. Potassium passes into the blood mainly between the cells. Source 3, 2
2. Uptake in the gut → In blood plasma In the space outside the cells, sodium is the most common positively charged particle. Potassium is present there only in small amounts. Source 1, 2
3. In blood plasma → Kidney · Aldosterone The kidney filters both ions and recovers most of the sodium; potassium is released in the collecting duct. The hormone aldosterone controls both processes. Source 2
4. Sodium-potassium pump → Potassium in the cell · ATP, Magnesium Because of the pumping, almost all of the body’s potassium is inside the cells, above all in muscle cells. Source 1, 2
5. Sodium-potassium pump → Sodium outside Sodium is continuously moved to the outside. This maintains a gradient: much sodium outside, little inside. Source 1
6. Potassium in the cell → Resting potential Potassium channels Potassium slowly flows out through channels. Because this separates charge, the inside of the cell is negatively charged. This state is called the resting potential. Source 1
7. Resting potential → Excitation Sodium channels When sodium channels open, sodium rushes in and reverses the voltage. This is how nerve impulses and the trigger for muscle movement arise. Source 1
8. Sodium outside → Sodium co-transport SGLT and others The sodium gradient drives further transporters. SGLT pulls glucose into the cell together with sodium; other carriers move amino acids in the same way. Source 4

Cofactors in this pathway

• ATP — Energy source of the sodium-potassium pump, which splits one ATP per cycle Source 1
• Magnesium — Forms the complex with ATP that the sodium-potassium pump uses Source 1In the ORY catalogue as a laboratory value: Magnesium
• Chloride — Absorbed together with sodium in the small intestine via parallel exchangers Source 3
• Bicarbonate — Exchanged for chloride in the small intestine, in parallel with sodium-proton exchange via NHE3 Source 3
• Glucose — Carried into the cell together with sodium by the SGLT transporter Source 4

What acts on this pathway

• Spironolactone — Spironolactone occupies the aldosterone receptor in the kidney. As a result, less sodium is recovered there and less potassium is released. The prescribing information describes this mechanism. Source 5

Sources

1. Clausen MV, Hilbers F, Poulsen H. The Structure and Function of the Na,K-ATPase Isoforms in Health and Disease. Front Physiol 2017 · PubMed 28634454
2. Palmer BF. Regulation of Potassium Homeostasis. Clin J Am Soc Nephrol 2015 · PubMed 24721891
3. Kato A, Romero MF. Regulation of electroneutral NaCl absorption by the small intestine. Annu Rev Physiol 2011 · PubMed 21054167
4. Wright EM, Loo DD, Hirayama BA. Biology of human sodium glucose transporters. Physiol Rev 2011 · PubMed 21527736
5. US prescribing information Aldactone (Spironolactone, DailyMed), section 12.1 Mechanism of Action · Prescribing information

Whole pathway: Sodium and potassium

As of 2026-09-16. Draft written by Claude to schema v2; sources checked in PubMed; expert review pending
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