Free fatty acids/triglycerides increase ocular and subcutaneous blood flow

Abstract

Elevated plasma free fatty acids (FFA) induce skeletal muscle insulin resistance and impair endothelial function. The aim of this study was to characterize the acute hemodynamic effects of FFA in the eye and skin. A triglyceride (Intralipid 20%, 1.5 ml/min)/heparin (bolus: 200 IU; constant infusion rate: 0.2 IU · kg−1· min−1) emulsion or placebo was administered to 10 healthy subjects. Measurements of pulsatile choroidal blood flow with laser interferometry, retinal blood flow with the blue field entoptic technique, peak systolic and end diastolic blood velocity (PSV, EDV) in the ophthalmic artery with Doppler sonography, and subcutaneous blood flow with laser Doppler flowmetry were performed during an euglycemic somatostatin-insulin clamp over 405 min. Plasma FFA/triglyceride elevation induced a rise in pulsatile choroidal blood flow by 25 ± 3% ( P < 0.001) and in retinal blood flow by 60 ± 23% ( P= 0.0125). PSV increased by 27 ± 8% ( P = 0.001), whereas EDV was not affected. Skin blood flow increased by 149 ± 38% ( P = 0.001). Mean blood pressure and pulse rate remained unchanged, whereas pulse pressure amplitude increased by 17 ± 5% ( P = 0.019). Infusion of heparin alone had no hemodynamic effect in the eye or skin. In conclusion, FFA/triglyceride elevation increases subcutaneous and ocular blood flow with a more pronounced effect in the retina than in the choroid, which may play a role for early changes of ocular perfusion in the insulin resistance syndrome.