ABSTRACT
The most obvious effect of thyroid hormones in animals consists of the increase of basal metabolic rate (the ‘‘calorigenic effect’’). The original assumption that thyroid hormones uncouple oxidative phosphorylation of mitochondria (1,2) was later withdrawn (3,4). The stimulation of cell respiration by thyroxin (T4) or its physiologically active derivative 3,3′,5-triiodo-l-thyronine (T3) was explained by turning on the expression of modified enzyme patterns, particularly in mitochondria (5,6) via binding of the hormone to the nuclear thyroid hormone receptor (7).
