Comparison of the lipolytic activity of adipocytes isolated from white adipose tissue in Zucker and Wistar rats. In vitro effects of 3,5,3'-triiodo-L-thyronine

The in vitro effects of 3,5,3'-triiodo-L-thyronine (L-T3) on (-) epinephrine stimulated lipolytic activity were studied in adipocytes isolated from white adipose tissue of Zucker and Wistar male rats. Basic lipolytic activity was small and nearly insensitive to epinephrine in Zucker genetically obese rats. On the other hand, lipolytic activity was stimulated by epinephrine in Zucker lean rats and Wistar rats in the same way. There was no synergistic interaction between epinephrine and L-T3 on lipolytic activity, since the released glycerol levels were nearly the same. These data corroborate the hypothyroid status of Zucker genetically obese rats.