Water-free sodium accumulation.
The widely accepted concept of body fluid and electrolyte homeostasis is that Na(+) is restricted mainly to the extracellular fluid and K(+) to the intracellular space, where both ions act to hold water and thereby control the extracellular and intracellular fluid volume by their osmotic activity. Na(+) accumulation thus inevitably leads to water retention. The constancy of the extracellular volume is the task of the kidneys, which control the total body Na(+) content. More recent data have questioned this traditional view, suggesting that large amounts of Na(+) can be accumulated without accompanying water retention by osmotically inactive Na(+) retention, or by osmotically neutral Na(+)/K(+) exchange. Besides the control of the body Na(+) content by the kidneys, redistribution of body electrolytes hence provides an extrarenal regulatory alternative in the maintenance of body fluid volume and blood pressure control.
Titze
Jens
J
Department of Nephrology and Hypertension, Friedrich-Alexander University, Glückstrasse 6, Erlangen-Nürnberg, Germany. jtitze@molmed.uni-erlangen.de
D001825:Body Fluid Compartments / Q000502:physiology*; D006801:Humans; D006973:Hypertension / Q000378:metabolism* / Q000503:physiopathology; D009994:Osmolar Concentration; D009997:Osmotic Pressure; D012964:Sodium / Q000378:metabolism*; D014882:Water-Electrolyte Balance / Q000502:physiology
D012964:Sodium