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Curr Opin Nephrol Hypertens. 2006 Jul;15(4):430-6.

Control of potassium excretion: a Paleolithic perspective.

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Renal Division, St. Michael's Hospital, University of Toronto, Toronto, Ontario, Canada.



Regulation of potassium (K) excretion was examined in an experimental setting that reflects the dietary conditions for humans in Paleolithic times (high, episodic intake of K with organic anions; low intake of NaCl), because this is when major control mechanisms were likely to have developed.


The major control of K secretion in this setting is to regulate the number of luminal K channels in the cortical collecting duct. Following a KCl load, the K concentration in the medullary interstitial compartment rose; the likely source of this medullary K was its absorption by the H/K-ATPase in the inner medullary collecting duct. As a result of the higher medullary K concentration, the absorption of Na and Cl was inhibited in the loop of Henle, and this led to an increased distal delivery of a sufficient quantity of Na to raise K excretion markedly, while avoiding a large natriuresis. In addition, because K in the diet was accompanied by 'future' bicarbonate, a role for bicarbonate in the control of K secretion via 'selecting' whether aldosterone would be a NaCl-conserving or a kaliuretic hormone is discussed.


This way of examining the control of K excretion provides new insights into clinical disorders with an abnormal plasma K concentration secondary to altered K excretion, and also into the pathophysiology of calcium-containing kidney stones.

[Indexed for MEDLINE]

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