Novel experimental protocol to increase specific plasma nonesterified fatty acids in humans.

Abstract

Novel experimental protocol to increase specific plasma nonesterified fatty acids in humans. Am J Physiol Endocrinol Metab 284: E18–E24, 2003. First published September 17, 2002; 10.1152/ajpendo.00113.2002.—This study reports a novel protocol to increase plasma monounsaturated, polyunsaturated, and saturated nonesterified fatty acids (NEFA) in eight healthy volunteers (age 29–54 yr, body mass index 23–26 kg/m2 ). This was achieved by feeding small boluses of fat at different time points (35 g at 0 min and 8 g at 30, 60, 90, 120, 150, 180, and 210 min) in combination with a continuous low-dose heparin infusion. Olive oil, safflower oil, or palm stearin were used to increase monounsaturated, polyunsaturated, or saturated NEFAs, respectively. Plasma NEFA concentrations were increased for 2 h, when fat and heparin were given (olive oil: 745 35 mol/l; safflower oil: 609 37 mol/l, and palm stearin: 773 38 mol/l) compared with the control test (no fat and no heparin: 445 41 mol/l). During the heparin infusion, 18:1 n-9 was the most abundant fatty acid for the olive oil test compared with 18:2 n-6 for the safflower oil test and 16:0 for the palm stearin test (P 0.01). The method described here successfully increases several types of plasma NEFA concentrations and could be used to investigate differential effects of elevated individual NEFAs on metabolic processes.