Water-free Na+ retention: interaction with hypertension and tissue hydration.
Electrolyte and body fluid homeostasis in higher vertebrates is believed to be fully understood. The paradigm 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 from balance studies in humans 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 and Nikolaus Fiebiger Center for Molecular Medicine, Friedrich Alexander University, Erlangen-Nurnberg, Germany. jens.titze@rzmail.uni-erlangen.de
D000818:Animals; D001825:Body Fluid Compartments / Q000502:physiology*; D006025:Glycosaminoglycans / Q000502:physiology; D006801:Humans; D006973:Hypertension / Q000503:physiopathology*; D009994:Osmolar Concentration; D009997:Osmotic Pressure; D011188:Potassium / Q000378:metabolism; D012964:Sodium / Q000097:blood / Q000378:metabolism*; D014882:Water-Electrolyte Balance / Q000502:physiology*
D006025:Glycosaminoglycans; D012964:Sodium; D011188:Potassium