Acute Hyperlipidemia Increases Vasodilation in Conduit Arteries but Has No Effect on Microvascular Recruitment in African American Women

African Americans have one of the highest prevalence of hypertension in the United States. Impaired endothelial function has been implicated in the pathophysiology of hypertension in this group. We previously reported that brachial artery diameter increases from 3.9±0.14 to 4.1± 0.14 at 4 hours after ingestion of a high fat meal, suggesting vasodilation of conduit arteries. Considering that oral fat ingestion stimulates the release of gastrointestinal peptides with vasoactive properties, we aimed to isolate the vascular effect of fat on conduit artery and microvasculature by inducing an acute elevation of triglycerides and free fatty acids with an infusion of 20% intralipid® and heparin. To assess endothelial function we measured changes in the diameter of the brachial artery to hyperemia with a continuous edge detection and wall tracking software. Effect on microvasculature was obtained with contrast-enhanced ultrasonography (CEU) of the brachioradialis muscle with lipid-perflutren microbubbles infusion. We studied 14 obese healthy African American women, age 39± 10, BMI 38.7± 3.4 kg/m. 2 Triglycerides increased from 60.7±30.5 to 523.3±231 mg/dL at the end of the 4 h infusion. Brachial artery diameters were 3.6±0.16 and 3.9±0.18 mm at baseline, and 4-h, P=0.109, respectively. Flow mediated dilation improved at the end of the 4-h infusion period (4.3±0.95 to 6.2±1.21%, P=0.016), figure . Microvascular blood volume did not change with the intervention 5.8±4.9 vs. 5.9±3.6, P=0.55. In conclusion, IV acute hyperlipidemia did not increase brachial artery diameter nor microvascular circulation, however it potentiates vascular reactivity in conduit arteries.