22-kDa and 20-kDa hGH isoforms show differential effects when assayed in 3T3-F442A and 3T3-F442A/C4 adipocytes.

To known whether 22.0-kDa human growth hormone (hGH22K) and the 20.0-kDa isoform (hGH20K) show different activities, we used 3T3-F442A and 3T3-F442A/C4 cells to evaluate their adipogenic and metabolic effects. Both isoforms had similar adipogenic and insulin-like activities. Lipolytic and diabetogenic effects of hGH22K were, respectively, 12.5 and 1.7-fold higher than those found for hGH20K. The 3T3-F442A/C4 clone was not responsive to insulin-like and diabetogenic effects of hGH. The results suggest that adipogenic and lipolytic effects of hGH are mediated by mechanisms different from those involved in insulin-like and diabetogenic activities.