Studies were conducted to determine whether regional free fatty acid (FFA) release is differentially regulated by insulin. Systemic, leg, and splanchnic palmitate rate of appearance ([9,10-3H]palmitate) was measured in 26 healthy adults using the euglycemic-hyperinsulinemic clamp technique to achieve a physiological range of plasma insulin concentrations. We found that insulin inhibited systemic, leg, and splanchnic palmitate release in a dose- dependent fashion over the range of insulin infused (0-1.0 mU · kg-1 · min-1). Progressive hyperinsulinemia changed the leg from a net producer to a net FFA consumer, whereas the splanchnic bed converted from a net FFA consumer to a net producer. At the 0.5 mU · kg-1 · min-1 insulin infusion rate, leg FFA release was almost completely suppressed, whereas even with the 1.0 mU · kg-1 · min-1 insulin infusion rate, splanchnic FFA release decreased by only ~65% (P < 0.05 leg vs. splanchnic). These results demonstrate the regional heterogeneity of insulin-regulated FFA release in vivo, and indicate that visceral adipose tissue lipolysis is more resistant to insulin suppression than is leg lipolysis in humans.
ASJC Scopus subject areas
- Internal Medicine
- Endocrinology, Diabetes and Metabolism