Potassium depletion increases potassium clearance capacity in skeletal muscles in vivo during acute repletion.
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.
Bundgaard
Henning
H
Medical Department B 2142, The Heart Centre, Rigshospitalet, National University Hospital, University of Copenhagen, Blegdamsvej 9, 2100 Copenhagen, Denmark. henningbundgaard@dadlnet.dk
Kjeldsen
Keld
K
D000818:Animals; D005260:Female; D007262:Infusions, Intravenous; D008274:Magnesium / Q000378:metabolism; D020714:Maximum Tolerated Dose; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism*; D010042:Ouabain / Q000493:pharmacokinetics; D011188:Potassium / Q000378:metabolism* / Q000493:pharmacokinetics; D011189:Potassium Chloride / Q000008:administration & dosage*; D011191:Potassium Deficiency / Q000378:metabolism*; D017419:Potassium, Dietary / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D012964:Sodium / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
D017419:Potassium, Dietary; D010042:Ouabain; D011189:Potassium Chloride; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D008274:Magnesium; D011188:Potassium