Under basal conditions (low circulating Ang II and low Aldosterone), WNK4 will inhibit NCC function. It has been proposed that in the event of hyperkalemia and an increased secretion of aldosterone (which will upregulate both ENac and ROMK), this inhibition of NCC, will allow an increase in the arrival of sodium to the distal nephron (rich in ENaC and ROMK) which will allow the exchange of sodium for potassium ions, thereby reducing plasma potassium levels, without increasing sodium chloride retention (which is always accompanied by volume expansion). Furthermore it has been proposed that in the presence of AngII the WNK4 mediated NCC inhibition will be suppressed thereby increasing sodium-chloride reabsorption in the distal convoluted tubule. This along with the concomitant increase in passive water reabsortion due to the increased salt load in the distal convluted tubule cells will ultimately increase circulating volume.
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