Abstract
The effects of triiodothyronine (T3) on oxygen consumption (QO2), Na/K ATPase activity and mitochondrial alpha glycerophosphate dehydrogenase (αGPD) activity in BAT and liver were studied in newborn rabbits. Each of seven 5 day old litters was divided in half, and the newborns injected with either T3 (20 μg/100 g BW/day, SC) or vehicle for 3 days. Basal QO2 with and without ouabain was determined on isolated BAT cells or chopped liver. αGPD and Na/K ATPase were measured on tissue from individual animals. T3 stimulated BAT QO2, mean (±SEM)=119±18 vs 65±4 μl O2/106 cells ·hr in controls, p<0.005; there was no effect of ouabain in either group. BAT αGPD increased in response to T3 (1850±119 ΔOD × 103/mg protein·min vs 1266±121 in controls, p<0.005), but Na/K ATPase was unchanged. Hepatic QO2 was similar in T3 treated and control animals; ouabain suppressed respiration by ∼30% in both groups. Hepatic αGPD showed no response to T3, while Na/K ATPase was significantly increased (0.307±.025 μMPi/mg protein·hr vs 0.202±.021 in controls, p<0.003). Conclusions: 1) BAT respiration and mitochondrial αGPD but not Na/K ATPase are thyroid sensitive in the newborn rabbit. 2) Hepatic Na/K -ATPase activity is responsive to T3 but αGPD and respiration are not. 3) T3 stimulation of respiration is dissociated from changes in Na/K ATPase activity in liver and BAT.
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Klein, A., Jenkins, J., Reviczky, A. et al. 260 DISSOCIATION OF THYROID HORMONE STIMULATED RESPIRA-TION AND Na/K ATPase ACTIVITY IN BROWN ADIPOSE TISSUE (BAT) AND LIVER IN THE NEWBORN RABBIT. Pediatr Res 15 (Suppl 4), 483 (1981). https://doi.org/10.1203/00006450-198104001-00271
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DOI: https://doi.org/10.1203/00006450-198104001-00271