This study will investigate free fatty acid and VLDL-TG metabolism before and during exercise with and without pharmacological antilipolysis by the niacin antagonist Acipimox. Main focuses will be VLDL-TG and free fatty acid metabolism as well as expression of membrane proteins in fat- and muscle biopsies.

Insulin resistance in liver and skeletal muscle is of central pathogenic significance in the development of type 2 diabetes. The molecular connections are unresolved but high levels of free fatty acids and triglyceride is probably involved. Diabetic subjects and to a lesser extent obese subjects have increased triglyceride levels, this could be due to an abnormal turnover of VLDL-TG. It is not yet investigated whether VLDL-TG kinetics changes during pharmacological antilipolysis. Using the aseptic ex-vivo labeling technique (developed in our laboratories) we will investigate this issue in sedentary healthy men. After a 3 hour basal period subjects will exercise on a bike for 60 minutes at 60% of VO2max. In both basal and exercise period one muscle and one fat biopsy will be obtained, further blood samples will be drawn to examine FFA and VLDL-TG metabolism etc..

This new knowledge will contribute to the understanding of metabolic disorders like type 2 diabetes and obesity.

Inclusion Criteria:

- healthy, untrained males

Exclusion Criteria:

• medication
• history of malignancy, alcohol abuse or drug abuse
• participation in isotope trials in the last 6 months