Endothelium-dependent vasodilation, insulin resistance and the metabolic syndrome in an elderly cohort: The Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study

Background Only a few previous studies have investigated endothelium-dependent vasodilation in the metabolic syndrome (MetS). In the Prospective Study of the Vasculature in Uppsala Seniors (PIVUS) study, different techniques to assess vasodilation in conduit and resistance arteries were evaluated in relation to the MetS and insulin resistance. Methods In this population-based study, 1016 subjects aged 70 were evaluated by the invasive forearm technique with acetylcholine (EDV), brachial artery ultrasound to assess flow-mediated vasodilation (FMD) and pulse wave analysis with a beta-2 receptor agonist challenge, terbutaline. Results EDV was lower in subjects with the MetS (NECP/ATP III-criteria, prevalence 23%) compared to those without (p < 0.0001), and declined with increasing number of MetS criteria (p < 0.0001), after adjustment for coronary heart disease, stroke and cardiovascular medication. Also a reduced pulse wave response (p = 0.015), but not FMD (p = 0.64), was seen in those with the MetS. EDV and the pulse wave response, but not FMD, were inversely related to insulin resistance evaluated by the HOMA index. Also endothelium-independent vasodilation (EIDV) induced by intra-brachial infusion of sodium nitroprusside was impaired in subjects with MetS and in insulin resistance. Conclusions Vasodilation evaluated with the invasive forearm technique and pulse wave analysis with a beta-2 agonist, but not FMD, was reduced in elderly subjects with the MetS and was related to insulin resistance. Also EIDV showed the same pattern, suggesting a general deterioration in vasoreactivity mainly in resistance arteries in elderly subjects with the MetS.