Potassium deficiency enhances the effect of thyroid hormone on NaK-ATPase in liver and kidney.
In order to examine the possibility that the changes in electrolytes in tissue alter the effect of thyroid hormone on NaK-ATPase, rats were fed either synthetic K-deficient diet or synthetic K-normal diet. K-deficient diet induced a reduction in K content in serum or kidney, while that of the liver remained unchanged. When a daily dose of 2.5 micrograms T3 was administered for 7 days to k-deficient rats, both Mg- and NaK-ATPase of the homogenate of liver and kidney were elevated, while the same dose failed to influence those enzymes in K-normal rats. Furthermore, T3 dose increased the Na content of liver and kidney in K-deficient rats, resulting in a significant decrease in th K/Na ratio in those tissue. Based on the estimation from chloride space, the decrease in K/Na was deemed to have occurred mainly in the intracellular space. As the levels of serum thyroid hormone and liver T3 were not influenced by K-deficiency, the effect of K depletion is likely to be mediated not through the alteration in thyroid hormone kinetics, but through some other mechanism such as the elevation of intracellular Na. The present study demonstrates that K deficiency may sensitize NaK-ATPase to the effect of thyroid hormone.
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D017301:Ca(2+) Mg(2+)-ATPase; D007668:Kidney / Q000201:enzymology*; D008099:Liver / Q000201:enzymology*; D008297:Male; D011188:Potassium / Q000378:metabolism; D011191:Potassium Deficiency / Q000201:enzymology*; D051381:Rats; D012964:Sodium / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000378:metabolism / Q000494:pharmacology*
D014284:Triiodothyronine; D012964:Sodium; D000251:Adenosine Triphosphatases; D017301:Ca(2+) Mg(2+)-ATPase; D000254:Sodium-Potassium-Exchanging ATPase; D013974:Thyroxine; D011188:Potassium