AJP - Endocrinology and Metabolism, Vol 241, Issue 6 449-E453, Copyright © 1981 by American Physiological Society
Thyroid hormone-sensitive brown adipose tissue respiration in the newborn rabbit
A. H. Klein, J. J. Jenkins, A. Reviczky and D. A. Fisher
The effects of thyroid hormone treatment on brown adipose tissue (BAT) and
liver metabolism were assessed by measuring oxygen consumption,
sodium-potassium adenosine triphosphatase (Na-K-ATPase), and mitochondrial
alpha-glycerophosphate dehydrogenase (alpha-GPD) activities in tissues from
triiodothyronine- (T3) and vehicle-injected (for 3 days) newborn and adult
rabbits. In the newborns, basal BAT cellular respiration was increased
[mean (%/- SE) = 119 +/- 18 vs. 65 +/- 4 microliter O2/10(6) cells-1 . h in
controls (P less than 0.005)], whereas hepatic respiration was unchanged.
Ouabain had no effect on basal BAT cellular respiration, but suppressed
hepatic respiration by 30% in both newborn groups. T3 treatment had no
effect on NE- (10(-6) M) stimulated BAT respiration, whereas adult hepatic
respiration was increased almost twofold. alpha-GPD activities were
increased in both newborn BAT and adult liver but not in newborn liver.
Na-K-ATPase activity was significantly increased only in newborn liver. In
conclusion, 1) both BAT and liver are thyroid-hormone sensitive in the
newborn rabbit, but the responses to T3 treatment are different in the two
tissues; 2) the failure to stimulate both hepatic alpha-GPD and respiration
in the newborn appears to be a developmental phenomenon characteristic of
the rabbit; 3) thyroid hormones have little effect on sodium
transport-dependent respiration in either BAT of liver in the newborn
rabbit.
