Effect of fatty acids on mitochondrial function in skeletal muscle cells

• Grant number: 06/04978-1
• Support type: Scholarships abroad - Research
• Effective date (Start): June 01, 2007
• Effective date (End): October 31, 2007
• Field of knowledge: Biological Sciences - Physiology - Physiology of Organs and Systems
• Principal researcher: Sandro Massao Hirabara
• Grantee: Sandro Massao Hirabara
• Host: Pierre Maechler
• Home Institution: Pessoa Física
• Research place: Université de Genève, Switzerland

Abstract

Increased plasma levels of free fatty acids (FFA) occur in conditions of insulin resistance such as type 2 diabetes mellitus and obesity. These high levels of plasma FFA have been postulated to play an important role for the development of insulin resistance but the mechanisms involved remain to be fully established. We demonstrated that FFA may interfere in the glucose metabolism in skeletal muscle by Randle cycle, inhibition of insulin signaling pathways, and mitochondrial uncoupling. Recent studies suggest that FFA can also impair mitochondrial function in skeletal muscle cells. In this study, it will be investigated if the FFA-induced insulin resistance in skeletal muscle cells is related to a mitochondrial function. C2C12 skeletal muscle cells and rat skeletal muscle cells will be transfected with luciferase (an ATP-sensible enzyme) and cultured by 48 hours in the absence or presence of different FFA (palmitic, oleic, linoleic and eicosapentaenoic acid). After this period, the cells will be incubated in the absence or presence of 10 mU/mL insulin by 30 min. Electrical polarity of the inner mitochondrial membrane will be evaluated in real time by fluorimetry using rhodamine 123 as mitochondrion-specific fluorescent marker. ATP generation will be also measured in real time by luminescence through luciferase assay. Moreover, it will be determined if the effects of FFA on ATP generation occur in skeletal muscle in vivo during euglycemic-hyperinsulinemic clamp. Thus, it will be possible to determine if the FFA-induced insulin resistance in skeletal muscle is associated to a mitochondrial function. (AU)