Time course of the renal response to triiodothyronine in the rat.
Experiments were carried out to compare temporal changes in glomerular filtration rate (GFR), filtered Na+ load, and renal cortical (Na+ + K+)-adenosine triphosphatase (Na-K-ATPase) activity in the hypothyroid rat after administration of a single dose of triiodothyronine (T3) (50 microgram/100 g body wt). The cortex showed an increase in Na-K-ATPase at 24 h and progressive increases to a peak of 62% at 48 h. GFR and filtered Na+ load showed no changes at 24 and 48 h. At 72h, however, significant increases of 62 and 63% (per rat) were observed in GFR and filtered Na+ load, respectively. The results show that the early increase in Na-K-ATPase activity upon T3 treatment precedes the increases in GFR and filtered Na+ load, suggesting a direct effect of T3 on the regulation of Na-K-ATPase activity in the hypothyroid rat kidney cortex, rather than a secondary response to a primary increase in filtered Na+ load as proposed previously.
D000818:Animals; D005919:Glomerular Filtration Rate / Q000187:drug effects; D007037:Hypothyroidism / Q000503:physiopathology*; D007668:Kidney / Q000187:drug effects / Q000503:physiopathology*; D007672:Kidney Cortex / Q000201:enzymology; D007700:Kinetics; D008297:Male; D051381:Rats; D012964:Sodium / Q000097:blood*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D014284:Triiodothyronine / Q000494:pharmacology*
D014284:Triiodothyronine; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase