THYROID HORMONES: CONTROL OF TERMINAL OXIDATION.

Triiodothyronine administered to thyroidectomized rats preferentially increased the total capacity of the electron transport phosphorylation system when isolated mitochondria from the liver were tested with different substrates, but it caused little increase in the activity of the slowest dehydrogenases and no uncoupling. The increased activity appeared to be partly due to direct activation of some component of the electron transport system, although triiodothyronine injection also stimulated the incorporation of amino acids by isolated mitochondria.