Renal K(+) retention in physiological circumstances: focus on adaptation of the distal nephron and cross-talk with Na(+) transport systems

Consumption of salt (NaCl) and potassium (K(+)) has been completely modified, switching from a rich-K(+)/low-NaCl diet in the hunter–gatherer population to the opposite in the modern, westernized population. The ability to conserve K(+) is crucial to maintain the plasma K(+) concentration in a physiological range when dietary K(+) intake is decreased. Moreover, a chronic reduction in the K(+) intake is correlated with an increased blood pressure, an effect worsened by a high-Na(+) diet. The renal adaptation to a low-K(+) diet in order to maintain the plasma K(+) level in the normal range is complex and interconnected with the mechanisms of the Na(+) balance. In this short review, we will recapitulate the general mechanisms allowing the plasma K(+) value to remain in the normal range, when there is a necessity to retain K(+) (response to low-K(+) diet and adaptation to gestation), by focusing on the processes occurring in the most distal part of the nephron. We will particularly outline the mechanisms of K(+) reabsorption and discuss the consequences of its absence on the Na(+) transport systems and the regulation of the extracellular compartment volume and blood pressure.