Tri-iodothyronine enhances the formation of light mitochondria during cold exposure.
The effect of cold exposure and of PTU and PTU + T3 administration on the protein content and succinic dehydrogenase activity of three mitochondrial populations obtained from rat liver was examined. Our results indicated the following: Succinic dehydrogenase activity increases mainly in the light mitochondrial fraction of cold-exposed rats. PTU administration of cold-exposed animals does not affect the increment in enzyme activity of the heavy fraction but blocks the increment of the light fraction. PTU + T3 administration restores succinic dehydrogenase activity to the values prevalent in normal cold-exposed rats. These findings suggest that thyroid hormone may stimulate the formation of light mitochondria during cold exposure.
D000064:Acclimatization; D000818:Animals; D003080:Cold Temperature; D007037:Hypothyroidism / Q000503:physiopathology; D008297:Male; D008930:Mitochondria, Liver / Q000187:drug effects / Q000201:enzymology / Q000648:ultrastructure*; D011441:Propylthiouracil / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013385:Succinate Dehydrogenase / Q000378:metabolism; D014284:Triiodothyronine / Q000097:blood / Q000494:pharmacology*
D014284:Triiodothyronine; D011441:Propylthiouracil; D013385:Succinate Dehydrogenase