Objective-Hypercholesterolemia markedly impairs endothelial function. Whether this is the case for hypertriglyceridemia is less clear, however, and limited evidence exists on the effect of an acute increase in triglyceridemia caused by a high-fat meal. Methods and Results-In 16 normotensive subjects with an untreated mild hypertriglyceridemia and dyslipidemia and in 7 normal controls, we measured radial artery diameter and blood flow by an echo-tracking device (NIUS02). Data were obtained at

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... eline, at the release of a 4-minute ischemia of the hand, which causes an increase in arterial diameter dependent on nitric oxide (NO) secretion, and at the release of a 12-minute exclusion of the arm by an arm cuff to obtain a larger increase in arterial diameter mainly of nonendothelial nature. Measurements were performed before and 6 hours after a high-fat meal (680 kcal/m 2 body surface; 82% lipids). In mild dyslipidemic hypertriglyceridemic subjects, the high-fat meal did not alter baseline blood pressure (beat-to-beat finger measurement), heart rate, radial artery diameter, and blood flow. It also did not alter the increase in blood flow induced by the 4-minute ischemia (ϩ42.7Ϯ10.4 and ϩ43.7Ϯ10.4 mL/min), whereas it markedly attenuated the concomitant increase in arterial diameter (ϩ0.31Ϯ0.06 versus 0.13Ϯ0.06 mm; PϽ0.05). The alteration of the diameter response did not correlate with changes on total cholesterol, but it showed a significant correlation with the increase in serum triglycerides induced by high-fat meal (rϭ0.49, PϽ0.05). This attenuation was not seen in control subjects and in subjects in whom measurements were repeated after a 6-hour observation period. It was also not paralleled by an alteration of the endothelially independent response to a 12-minute ischemia whose larger effect on arterial diameter and blood flow were similar before and after the high-fat meal. Conclusions-Endothelial function is markedly impaired by a high-fat meal that causes an acute hypertriglyceridemia. This impairment is evident in dyslipidemic patients with baseline hypertriglyceridemia but not in normotriglyceridemic controls. (Arterioscler Thromb Vasc Biol. 2005;25:1-5.)