EFFECT OF INSULIN AND INSULIN-LIKE GROWTH-FACTOR-I ON GLUCOSE-TRANSPORT AND ITS TRANSPORTERS IN SOLEUS MUSCLE OF LEAN AND OBESE MICE

The mechanisms underlying insulin and insulin like growth factor-I (IG F-I) action on glucose transport share similar processes leading to Gl ut 4 translocation after respective receptor activation. Among these s teps are phosphorylation of insulin receptor substrate-1 (IRS-1) and a ctivation of phosphatidylinositol-3-kinase (PI3-kinase). This enzyme c ould be involved in stimulated glucose transport in muscle, since its inhibitor, wortmannin, blocks the hormonal effect in muscle, PI3-kinas e is activated by insulin and IGF-I in a rapid and transient manner in incubated soleus muscles. When PI3-kinase activation was studied in m uscle of obese insulin-resistant mice, there was a marked alteration i n the response to insulin both in vivo and in vitro, PI3-kinase activa tion by IGF-I was also altered in obese mice, although to a lesser deg ree. Copyright (C) 1995 by W.B. Saunders Company.