Potassium depletion increases potassium clearance capacity in skeletal muscles in vivo during acute repletion

Am J Physiol Cell Physiol. 2002 Oct;283(4):C1163-70. doi: 10.1152/ajpcell.00588.2001.

Abstract

Muscular K uptake depends on skeletal muscle Na-K-ATPase concentration and activity. Reduced K uptake is observed in vitro in K-depleted rats. We evaluated skeletal muscle K clearance capacity in vivo in rats K depleted for 14 days. [(3)H]ouabain binding, alpha(1) and alpha(2) Na-K-ATPase isoform abundance, and K, Na, and Mg content were measured in skeletal muscles. Skeletal muscle K, Na, and Mg and plasma K were measured in relation to intravenous KCl infusion that continued until animals died, i.e., maximum KCl dose was administered. In soleus, extensor digitorum longus (EDL), and gastrocnemius muscles K depletion significantly reduced K content by 18%, 15%, and 19%, [(3)H]ouabain binding by 36%, 41%, and 68%, and alpha(2) isoform abundance by 34%, 44%, and 70%, respectively. No significant change was observed in alpha(1) isoform abundance. In EDL and gastrocnemius muscles K depletion significantly increased Na (48% and 59%) and Mg (10% and 17%) content, but only tendencies to increase were observed in soleus muscle. K-depleted rats tolerated up to a fourfold higher KCl dose. This was associated with a reduced rate of increase in plasma K and increases in soleus, EDL, and gastrocnemius muscle K of 56%, 42%, and 41%, respectively, but only tendencies to increase in controls. However, whereas K uptake was highest in K-depleted animals, the K uptake rate was highest in controls. In vivo K depletion is associated with markedly increased K tolerance and K clearance despite significantly reduced skeletal muscle Na-K-ATPase concentration. The concern of an increased risk for K intoxication during K repletion seems unwarranted.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Female
  • Infusions, Intravenous
  • Magnesium / metabolism
  • Maximum Tolerated Dose
  • Muscle, Skeletal / drug effects
  • Muscle, Skeletal / metabolism*
  • Ouabain / pharmacokinetics
  • Potassium / metabolism*
  • Potassium / pharmacokinetics
  • Potassium Chloride / administration & dosage*
  • Potassium Deficiency / metabolism*
  • Potassium, Dietary / pharmacology*
  • Rats
  • Rats, Wistar
  • Sodium / metabolism
  • Sodium-Potassium-Exchanging ATPase / metabolism

Substances

  • Potassium, Dietary
  • Ouabain
  • Potassium Chloride
  • Sodium
  • Sodium-Potassium-Exchanging ATPase
  • Magnesium
  • Potassium