Uptake of thyroid hormones (L-T3 and L-T4) by isolated rat adipocytes

3,5,3'-triiodo-L-thyronine is taken up by isolated rat adipocytes under physiological conditions by a saturable sigmoidal process, while L-thyroxine uptake follows Michaelian kinetics. Comparative studies performed with intact adipocytes and derived liposomes suggest that thyroid hormones are taken up into cells via carrier-mediated transport.