What are the feedback control and feed forward effects in potassium balance?
Elevation of plasma potassium causes the activation of mechanisms (insulin and aldosterone effects) that lower plasma potassium. This is an example of a negative feedback system where potassium excretion increases in response to increases in the plasma potassium level.
On the other hand, a feed-forward system responds to potassium intake in a manner that is independent of changes in the systemic plasma potassium level. In sheep, intake of potassium-rich foods triggers a significant increase in urinary potassium excretion without an increase in the serum potassium. The signal between the gastrointestinal (GI) tract and the kidney potassium handling that is responsible for this feed-forward control is unknown.
