Although many factors are thought to contribute to the regulation of metabolic vasodilation in skeletal muscle vasculature, recent interest has focused on the role of the endothelium. We examined the relative roles of nitric oxide (NO) and of vasodilator prostanoids in the control of metabolically induced functional hyperemia in the forearm of humans. In 43 healthy volunteers [24 ± 5 (SD) yr] we assessed resting and functional hyperemic blood flow (FHBF) in response to 2 min of isotonic forearm exercise before and after inhibition of NO and/or vasodilator prostanoid production with intra-arterial N G-monomethyl-l-arginine (l-NMMA, 2 mg/min) and aspirin (ASA, 3 mg/min), respectively. Blood flow was measured using venous occlusion plethysmography.l-NMMA and ASA decreased resting forearm blood flow by 42% ( P < 0.0001) and 23% ( P < 0.0001), respectively, whereas infusion of ASA followed byl-NMMA reduced flow by a further 24% ( P < 0.05).l-NMMA reduced peak FHBF by 18% [from 13.9 ± 1.0 to 11.4 ± 1.1 (SE) ml ⋅ 100 ml forearm−1 ⋅ min−1, P = 0.003] and the volume “repaid” after 1 and 5 min by 25% (8.9 ± 0.7 vs. 6.7 ± 0.7 ml/100 ml, P < 0.0001) and 37% (26.6 ± 1.8 vs. 16.8 ± 1.6 ml/100 ml, P < 0.0001). ASA similarly reduced peak FHBF by 19% (from 14.5 ± 1.1 to 11.8 ± 0.9 ⋅ 100 ml forearm−1 ⋅ min−1, P < 0.001) and the volume repaid after 1 and 5 min by 14% (7.5 ± 0.6 vs. 6.4 ± 0.6 ml/100 ml, P = 0.0001) and 20% (21.2 ± 1.5 vs. 16.9 ± 1.5 ml/100 ml, P < 0.0001), respectively. The coinfusion of ASA andl-NMMA did not decrease FHBF to a greater extent than either agent alone. These data suggest that endothelium-derived NO and vasodilator prostanoids contribute to resting blood flow and metabolic vasodilation in skeletal muscle vasculature in healthy humans. Although these vasodilator mechanisms operate in parallel in exercise-induced hyperemia, they appear not to be additive. Other mechanisms must also be operative in metabolic vasodilation.

Long-term estrogen therapy appears to improve vascular function in male to female transsexuals and occurs despite higher triglyceride levels and the presence of small, dense LDL-C. The beneficial effects of estrogen are not gender specific or solely mediated through endothelium-derived nitric oxide.

BackgroundAbnormalities in the clinical markers of metabolic syndrome (MS) are associated with the development of cardiovascular disease, type 2 diabetes mellitus, and some cancers. MS prevalence in Korea increased between the mid-1990s and mid-2000s; however, no data on the recent trends of MS prevalence are available. Thus, we aimed to investigate the prevalence of MS, the five components of MS, and the related risk factors in Korean adults by using recent data.MethodsData from the Korean National Health and Nutrition Examination Survey conducted between 2008 and 2013 were used. The revised National Cholesterol Education Program criteria were used for defining MS. A multivariate logistic regression analyses was used to estimate the relationship between the related risk factors including behaviors, dietary factors, and the prevalence of MS.ResultsA total of 34,587 men and women were included in the analysis. Age-adjusted prevalence of MS in 2013 was 28.9% without a significant increasing or decreasing trend between 2008 and 2013. Among the five components of MS, abdominal obesity decreased in both men and women (annual percent change: −2.0 and −2.5%, respectively), the decrease being significant only in women, whereas blood pressure and blood glucose significantly increased in men (+1.9 and +2.7%, respectively). Age and obesity (odds ratio = 6.7, 95% confidence interval = 5.9–7.5 for body mass index ≥25 kg/m2 vs. body mass index <25 kg/m2) were associated with increased MS risk in both men and women. Smoking and alcohol drinking were significantly associated with increased MS risk in men, and association between MS and vitamin D deficiency was at the edge of statistical significance. Higher education and income level were significantly associated with decreased MS risk in women. During this period, smoking rate and physical activity, sodium intake, and serum vitamin D level significantly decreased. Education level, calorie intake, and intake of carbohydrate, fat, protein and calcium significantly increased.ConclusionSeveral factors contribute to the stable MS prevalence—on the one hand, increased prevalence of high blood sugar, high blood pressure, calorie intake, and physical inactivity, and on the other hand, decreased prevalence of abdominal obesity and smoking. Lifestyle interventions to prevent and control non-communicable diseases should be implemented at the national level to reduce the burden of MS.