title: Paradoxical potassium depletion: a renal mechanism for extrarenal potassium adaptation.
abstract: Following nephrectomy and acute potassium loading, animals previously maintained on a high potassium diet have a smaller increment in plasma potassium than do animals on a control diet. The mechanism of this "extrarenal potassium adaptation" is not known. To explore the role of potassium depletion in this process, we studied rats adapted to either a high potassium (HK) or control (C) diet. When dietary potassium was withdrawn, urinary potassium losses in HK rats greatly exceeded those in C rats for at least two days, leading to greater potassium depletion in HK than C animals. A smaller increment in plasma potassium in HK compared to C rats was seen only after prolonged fasting preceded nephrectomy and acute potassium loading. Correction of potassium depletion incurred during fasting abolished extrarenal potassium adaptation. We conclude: after withdrawal of dietary potassium, urinary potassium losses are much greater in HK than in C rats; if the duration of dietary potassium deprivation is sufficient, these urinary potassium losses will cause potassium-adapted animals to paradoxically become more potassium depleted than controls; and this paradoxical potassium depletion may be responsible for extrarenal potassium adaptation.
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects; D000818:Animals; D004032:Diet; D005215:Fasting; D007668:Kidney / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D009392:Nephrectomy; D011188:Potassium / Q000008:administration & dosage / Q000378:metabolism*; D011191:Potassium Deficiency / Q000209:etiology / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors
chemical_list: D011188:Potassium