Oxygen consumption and thyroid function in the squirrel monkey (Saimiri sciureus)

Thyroidal accumulation of 125I and the biological half-life of 131I-thyroxine were determined in the squirrel monkey. Oxygen consumption and the respiratory quotient were also measured. A peak uptake of 131I by the thyroid of 45.3% of the injected isotope occurred 4 hours after administration of the radioisotope. The biological half-life of the 131I-thyroxine was 22-24 hours. Oxygen consumption was 1.02 cm3 O2/g/hour and the respiratory quotient was 0.82. It was concluded that the squirrel monkey is hypermetabolic when compared with other laboratory animals of the same size.