Effect of blood free fatty acid level on endothelium-dependent vasodilation in rat aorta

Objective To explore the effect of blood free fatty acid (FFA) level on endothelium-dependent vasodilation. Methods Male SD rats were asigned to two groups. FFA group was infused with lipid emulsion and heparin intravenously for 4 hours; control group was infused with saline alone. At the end of infusion the rats were sacrificed and the aorta was removed. Each aortic ring with 3 mm in length was mounted in a WPI organ bath system at standardized tension. After equilibration, rings were contracted with PGF 2α, and then cumulative dose-response for relaxation to acetylcholine (10 -9～10 -4 mol/L) were obtained in each rings. Similar experiments were conducted with 10 -9～10 -4 mol/L sodium nitroprusside as the vasorelaxing agent. Results In response to increasing doses of acetylcholine aortic rings obtained from control rats demonstrated robust endothelium dependent relaxation, but aortic rings from FFA treated rats exhibited markedly impaired endothelium function. To the endothelium independent vasodilator sodium nitreoprusside, FFA treated aortic rings demonstrated normal relaxation. Conclusion Elevated blood FFA level results in endothelial dysfunction by a direct interaction with endothelium which suggests that elevated FFA levels may be proatherogenic.