Epinephrine inhibits insulin-stimulated muscle glucose transport

• Published in: Journal of applied physiology (1985) 2002-11, Vol.93 (5), p.1638-1643
• Main Authors: Hunt, Desmond G, Ivy, John L
• Format: Article
• Language: English
• Subjects: Adrenals. Interrenals; Adrenergic beta-Agonists - pharmacology; Adrenocortical hormones. Regulation; Animals; Biological and medical sciences; Biological Transport - drug effects; Drugs; Epinephrine - pharmacology; Fundamental and applied biological sciences. Psychology; Glucose; Glucose - antagonists & inhibitors; Glucose - metabolism; Hypoglycemic Agents - pharmacology; In Vitro Techniques; Insulin; Insulin - pharmacology; Insulin Receptor Substrate Proteins; Muscle Fibers, Fast-Twitch - metabolism; Muscle Fibers, Slow-Twitch - metabolism; Muscle, Skeletal - metabolism; Phosphatidylinositol 3-Kinases - metabolism; Phosphoproteins - metabolism; Rats; Rats, Sprague-Dawley; Vertebrates: endocrinology
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/japplphysiol.00445.2002

Exercise Physiology and Metabolism Laboratory, Department of Kinesiology and Health Education, University of Texas at Austin, Austin, Texas 78712 We recently demonstrated that epinephrine could inhibit the activation by insulin of insulin receptor substrate-1 (IRS-1)-associated phosphatidylinositol 3-kinase (PI3-kinase) in skeletal muscle (Hunt DG, Zhenping D, and Ivy JL. J Appl Physiol 92: 1285-1292, 2002). Activation of PI3-kinase is recognized as an essential step in the activation of muscle glucose transport by insulin. We therefore investigated the effect of epinephrine on insulin-stimulated glucose transport in both fast-twitch (epitrochlearis) and slow-twitch (soleus) muscle of the rat by using an isolated muscle preparation. Glucose transport was significantly increased in the epitrochlearis and soleus when incubated in 50 and 100 µU/ml insulin, respectively. Activation of glucose transport by 50 µU/ml insulin was inhibited by 24 nM epinephrine in both muscle types. This inhibition of glucose transport by epinephrine was accompanied by suppression of IRS-1-associated PI3-kinase activation. However, when muscles were incubated in 100 µU/ml insulin, 24 nM epinephrine was unable to inhibit IRS-1-associated PI3-kinase activation or glucose transport. Even when epinephrine concentration was increased to 500 nM, no attenuating effect was observed on glucose transport. Results of this study indicate that epinephrine is capable of inhibiting glucose transport activated by a moderate, but not a high, physiological insulin concentration. The inhibition of glucose transport by epinephrine appears to involve the inhibition of IRS-1-associated PI3-kinase activation. phosphatidylinositol 3-kinase; -adrenergic receptor; insulin receptor; insulin receptor substrate-1