Nuclear binding of T3 and effects of QO2, Na-K-ATPase, and alpha-GPDH in liver and kidney.
Thyroid status was altered by use of a low-iodine-perchlorate (PC) regimen and either reversal with NaI or injections of L-3,5,3'-triiodothyronine (T3). The PC regimen decreased renal and hepatic oxygen consumption (QO2), alpha-glycerophosphate dehydrogenase (alpha-GPDH), and Na+-K+-dependent adenosine triphosphatase (Na-K-ATPase) to comparable extents (25 vs. 23%, 26 vs. 39%, and 41 vs. 51%, respectively). Administration of T3 to hypothyroid rats elicited dose-dependent increases in hepatic and renal cortical QO2, ouabain-sensitive oxygen consumption (QO2(t)), alpha-GPDH, and Na-K-ATPase activities. The half-maximal increases in all of the response parameters in both kidney and liver were obtained at dosages of 6-32 micrograms T3/100 g body wt. The equivalences in the renal cortical vs. hepatic responses were indicated by correlation coefficients of approximately 0.97. Kidney and liver nuclei also showed similar high-affinity binding of 125I-T3-K1/2 = 29 vs. 18 micrograms T3/100 g body wt, and Nmax = 1.8 vs. 2.1 ng T3/mg DNA. The patterns of the responses plotted as a function of T3 occupancy of the high-affinity nuclear binding sites were indistinguishable in kidney and liver. These results imply similar modes of action of T3, probably initiated at the nuclear level, in both kidney and liver.
D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism; D005993:Glycerolphosphate Dehydrogenase / Q000378:metabolism*; D007668:Kidney / Q000201:enzymology* / Q000378:metabolism; D008099:Liver / Q000201:enzymology* / Q000378:metabolism; D008297:Male; D008433:Mathematics; D010101:Oxygen Consumption / Q000187:drug effects*; D051381:Rats; D011956:Receptors, Cell Surface / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D014284:Triiodothyronine / Q000494:pharmacology*
D011956:Receptors, Cell Surface; D014284:Triiodothyronine; D005993:Glycerolphosphate Dehydrogenase; D000254:Sodium-Potassium-Exchanging ATPase