Effect of triiodothyronine on rat liver polysome profiles and translational activity of mRNA after partial hepatectomy.

The administration of 3,5,3'-L-triiodothyronine (T3) (200 micrograms/100 g) to rats immediately after partial hepatectomy led to an increase in total polysome content of residual hepatocytes (as measured 18 h postoperatively) which exceeded that observed after partial hepatectomy in the absence of hormone. The percentage of free ribosome pool remained the same after partial hepatectomy irrespectively on the absence or presence of T3. After partial hepatectomy the sedimentation pattern of total polysomal fraction (isolated 18 h postoperatively) shifted towards smaller aggregates as compared with that isolated from sham operated animals. T3 did not affect this pattern. The translational capacity of mRNA isolated from regenerating liver after 18 h was higher than that of mRNA isolated from sham operated animals. T3 increased the translational capacity of mRNA isolated from regenerating liver if administered immediately after surgery. Two dimensional electrophoresis of translated products showed that one of the typical proteins recently characterized with Mr 25,000 pI 6.9 appeared after partial hepatectomy and was significantly increased when T3 was administered immediately after surgery. These results show that thyroid hormone can enhance some of the characteristics features of liver regeneration involved in the synthesis of proteins typical for the process of liver regeneration.