Figure 2.

A schematic depicting the complementary roles of the classic feedback and “feed-forward” control mechanisms for maintaining potassium homeostasis. An increase in plasma potassium evokes an array of responses that promote a kaliuresis. In contrast, the “feed-forward” control mechanism is engaged when dietary potassium is sensed by K⁺ sensors in the gastrointestinal tract in the absence of perceptible changes in plasma potassium. Courtesy of Murray Epstein.