Abstract
BackgroundImpaired vasoreactivity is often observed in subjects with metabolic syndrome, a condition that includes the presence of a specific cluster of risk factors for obesity and cardiovascular disease. However, hierarchical causes in the impaired vasoreactivity have not been clarified. We evaluated the impact of individual metabolic risk components or its clustering under the condition of insulin resistance on endothelial and smooth muscle cell function.MethodsVascular reactivity to acetylcholine (Ach), with or without nitric oxide synthase (NOS) inhibitor NG-monomethyl-l-arginine (L-NMMA), or sodium nitroprusside (SNP) by forearm venous occlusion plethysmography and insulin sensitivity index (M mg/kg/min) in euglycemic clamp were measured in men without (n = 18, control group) or with (n = 19, metabolic syndrome group) metabolic syndrome.Results(1) Ach-induced maximal forearm blood flow (maxFBF) was impaired in subjects with metabolic syndrome. In particular, the NOS-dependent component of Ach-induced maxFBF was selectively decreased, while the NOS-independent component remained relatively unchanged. (2) Ach-induced maxFBF and ∆Ach-induced maxFBF with L-NMMA were correlated with waist circumference, glucose, and triglycerides, and most strongly correlated with visceral fat area, adiponectin, and M. (3) Multivariate regression analysis indicated that individual metabolic risk components explained Ach-induced maxFBF by 4–21 %. Clustering of all metabolic risk components increased this to 35 %, and the presence of metabolic syndrome explained 30 %, indicating that defining metabolic syndrome can effectively predict impairment of endothelial dysfunction.ConclusionsEndothelial dysfunction was correlated with individual metabolic risk components, but more strongly with clustering of the components under a condition with low insulin sensitivity. We suggest that in subjects with metabolic syndrome, endothelial function is impaired by multiple cardiovascular risk factors exclusively when under the condition of insulin insensitivity and also that defining metabolic syndrome can effectively predict impairment of endothelial dysfunction.
Highlights
Impaired vasoreactivity is often observed in subjects with metabolic syndrome, a condition that includes the presence of a specific cluster of risk factors for obesity and cardiovascular disease
We suggest that in subjects with metabolic syndrome, endothelial function is impaired by multiple cardiovascular risk factors exclusively when under the condition of insulin insensitivity and that defining metabolic syndrome can effectively predict impairment of endothelial dysfunction
Impact of individual metabolic risk components and its clustering on endothelial and smooth muscle cell function Since metabolic syndrome is a cluster of relatively heterogeneous atherosclerotic risk factors, which may solely impair endothelial function, we evaluated the relationship between vascular reactivity and individual components or its clustering
Summary
Impaired vasoreactivity is often observed in subjects with metabolic syndrome, a condition that includes the presence of a specific cluster of risk factors for obesity and cardiovascular disease. We evaluated the impact of individual metabolic risk components or its clustering under the condition of insulin resistance on endothelial and smooth muscle cell function. The impaired vasoreactivity in this syndrome can be provoked by two scenarios [1]: (1) individual metabolic risk components such as high blood pressure, hyperglycemia, and dyslipidemia, or (2) its clustering under the condition of obesity and/ or insulin resistance. The current study compared the impact of individual metabolic risk components and its clustering under the condition of obesity and/or insulin resistance on endothelial and smooth muscle cell function in subjects with metabolic syndrome
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