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Abstract: FR-OR061

A Single Gastric K+ Load Induces Acute Diuresis in Mice

Session Information

Category: Fluid and Electrolytes

  • 901 Fluid and Electrolytes: Basic


  • Svendsen, Samuel L.C., Aarhus University, Aarhus, Denmark
  • Kornvig, Simon, Aarhus University, Aarhus, Denmark
  • Larsen, Casper Kornbech, LEO Pharma, Copenhagen SV, Denmark
  • Jensen, Iben Skov, Aarhus University, Aarhus, Denmark
  • Leipziger, Jens G., Aarhus University, Aarhus, Denmark
  • Sorensen, Mads Vaarby, Aarhus University, Aarhus, Denmark

K+ balance relies on regulated renal K+ excretion to match variable dietary K+ intake. Upon a K+ rich meal, rapid and effective urinary K+ excretion is obligatory. The renal adaptation to an acute K+ load involves an increase of the driving force for K+ secretion by shifting the distal tubular Na+ reabsorption from being electroneutral (NCC) to electrogenic (ENaC). In addition, K+ secretion in the CD is stimulated by increased luminal flow. Here we asked, if a high K+ intake acutely increases urinary flow.


Mice were K+ challenged through gavage, diets or a combination of these. After K+ loading urinary volume, [K+]u and [Na+]u ,plasma osmolality, [K+]p and [Na+]p were measured.


1) Mice switched from a 1% to a 2% K+ diet increased their diuresis markedly within 12h. 2) Mice switched from a 1% to a 0.01% K+ diet had a biphasic diuretic response. During the first 12h their diuresis decreased, whereas it increased from 12 to 36h. 3) A single K+ load, by gastric gavage, corresponding to 25-50% of daily K+ intake induced diuresis within 30 min. This occurred despite augmented plasma osmolality. [K+]u remained unchanged and therefore the increased urinary K+ excretion depended on the volume effect 4) K+ gavage did not changes urinary creatinine excretion suggesting a constant GFR. 5) Subsequently, a possible direct and acute effect of a plasma [K+] ([K+]bl) increase was tested in isolated perfused mTALs and CDs. An acute [K+]bl increase (from 3.6 to 6.5 mM) did not affect TAL NaCl absorption (measured 5 and 25 minutes post K+ jump). In contrast, the same manoeuver reduced the CDs sensitivity to stimulated AVP-mediated water absorption (measured 10 minutes post K+ jump).


Dietary K+ load induces a rapidly on setting diuresis. This increase in urinary volume appears crucial for a powerful K+ elimination since it appears prior to alteration in [K+]u. Based on preliminary data we suggest that the physiological mechanism of K+-induced diuresis involves AVP desensitization of the CD.


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