Non-esterified fatty acids regulate lipid and glucose oxidation and glycogen synthesis in healthy man.

UNLABELLED: We examined the interrelationship of lipid and glucose metabolism in the basal state and during insulin stimulus in 19 healthy men (27 +/- 2 years, body mass index 23.6 +/- 0.6 kg/m2). In each subject, we performed a 4-h euglycaemic (5.3 +/- 0.1 mmol/l) hyperinsulinaemic (647 +/- 21 pmol/l) insulin clamp with indirect calorimetry in the basal state and during insulin infusion, and muscle biopsies before and at the end of the clamp. In the basal state, serum non-esterified fatty acid levels correlated directly with lipid oxidation (r = 0.56, p < 0.05) and indirectly with glucose oxidation (r = -0.80, p < 0.001). Lipid and glucose oxidation rates were inversely related in the basal state (r = -0.47, p < 0.05) and during insulin infusion (r = -0.65, p < 0.01). Basal lipid oxidation and glycogen synthase total activity correlated inversely (r = -0.54, p < 0.05). Lipid oxidation both in the basal state (r = -0.61, p < 0.01) and during insulin infusion (r = -0.62, p < 0.05) was inversely related to muscle glycogen content after the insulin clamp. Fasting plasma triglyceride concentration correlated directly to fasting insulin (r = 0.55, p < 0.05) and C-peptide (r = 0.50, p < 0.03) concentrations and inversely to non-oxidative glucose disposal rate at the end of clamp (r = -0.54, p < 0.05). IN
CONCLUSION: 1) Serum non-esterified fatty acid concentration enhances lipid and reduces glucose oxidation. 2) Lipid oxidation is inversely related to total glycogen synthase activity.(ABSTRACT TRUNCATED AT 250 WORDS)