High-fat diets are associated with an increased risk of cardiovascular disease. A potential underlying mechanism for the increased cardiovascular risk is endothelial dysfunction. Nitric oxide (NO)-mediated endothelium-dependent vasodilation is critical in the regulation of vascular tone and overall vascular health. The aim of this study was to determine the influence of dietary fat intake on endothelium-dependent vasodilation. Forty-four middle-aged and older sedentary, healthy adults were studied: 24 consumed a lower fat diet (LFD; 29% ± 1% calories from fat) and 20 consumed a high-fat diet (HFD; 41% ± 1% calories from fat). Four-day diet records were used to assess fat intake, and classifications were based on American Heart Association guidelines (<35% of total calories from fat). Forearm blood flow (FBF) responses to acetylcholine, in the absence and presence of the endothelial NO synthase inhibitor N(G)-monomethyl-l-arginine (L-NMMA), as well as responses to sodium nitroprusside were determined by plethysmography. The FBF response to acetylcholine was lower (∼15%; P < 0.05) in the HFD group (4.5 ± 0.2 to 12.1 ± 0.8 mL/100 mL tissue/min) than in the LFD group (4.6 ± 0.2 to 14.4 ± 0.6 mL/100 mL tissue/min). L-NMMA significantly reduced the FBF response to acetylcholine in the LFD group (∼25%) but not in the HFD group. There were no differences between groups in the vasodilator response to sodium nitroprusside. These data indicate that a high-fat diet is associated with endothelium-dependent vasodilator dysfunction due, in part, to diminished NO bioavailability. Impaired NO-mediated endothelium-dependent vasodilation may contribute to the increased cardiovascular risk with high dietary fat intake.
Une alimentation riche en gras est associée à un plus haut risque de maladie cardiovasculaire. Parmi les mécanismes potentiels à la base de ce haut risque de maladie cardiovasculaire, il y a la dysfonction de l’endothelium. La vasodilatation endothéliodepéndante médiée par l’oxyde nitrique (NO) est essentielle à la régulation du tonus vasculaire et de la santé vasculaire globale. Cette étude se propose de déterminer l’effet de l’apport alimentaire en gras sur la vasodilatation endothéliodépendante. Quarantequatre adultes d’âge mûr et d’adultes âgées, sédentaires et en bonne santé, participent à cette étude au cours de laquelle 24 parmi eux ont un apport alimentaire faible en gras (LFD; 29 ± 1 % des calories provenant du gras) et 20 autres, un apport riche en gras (HFD; 41 ± 1% des calories provenant du gras). On utilise le carnet alimentaire de 4 jours pour évaluer l’apport en gras et on se réfère aux directives de l’AHA (American Heart Association) pour la classification (<35 % de toutes les calories provenant du gras). On évalue par la pléthysmographie le débit sanguin dans l’avant-bras (FBF) en réponse à l’acétylcholine, et ce, en présence et en l’absence de NG-monométhyl-
Keywords: cardiovascular disease; débit sanguin dans l’avant-bras; endothelium; endothélium; forearm blood flow; high-fat diet; maladie cardiovasculaire; nitric oxide; oxyde nitrique; régime riche en gras; vasodilatation; vasodilation.