Functional dilator capacity is independently associated with insulin sensitivity and age in central obesity and is not improved by high dose statin treatment.

Institute of Developmental Sciences, School of Medicine, University of Southampton, Southampton General Hospital (MP 887), Southampton, UK.
Microcirculation (New York, N.Y.: 1994) (Impact Factor: 2.26). 01/2011; 18(1):74-84. DOI: 10.1111/j.1549-8719.2010.00070.x
Source: PubMed

ABSTRACT To test the hypothesis that: (i) functional microvascular dilator capacity is independently associated with insulin sensitivity and age in individuals with central adiposity at risk of cardiovascular disease (CVD); and (ii) functional microvascular dilator capacity is improved by high dose statin treatment.
Functional dilator capacity (measured as change in laser Doppler blood flux from baseline during post occlusive reactive hyperemia [peak flux%resting flux; PF%RF] and flowmotion (power spectral density [PSD] analysis)) were assessed in 40 people with central adiposity and one or more other CVD risk factors. Measurements were made at rest and during acute hyperinsulinaemia before and six months after high dose atorvastatin (40 mg daily) or placebo.
Insulin-induced change in PF%RF was independently associated with insulin sensitivity (M/I) (r = 0.46 p = 0.02) and age (r = -0.46 p = 0.02), which together explained almost half of the variance in PF%RF (adjusted r² = 0.37, p = 0.008). Whilst atorvastatin decreased LDL cholesterol by 51% (p < 0.001), PF%RF and flowmotion remained unchanged.
Insulin sensitivity and age are independently associated with an insulin-induced change in functional microvascular dilator capacity in individuals with central adiposity at risk of CVD. Dilator capacity is not improved by six months high dose statin treatment.

  • [Show abstract] [Hide abstract]
    ABSTRACT: We have evaluated the dynamics of skin microvascular blood flow (BF) and tissue oxygenation parameters (OXY) measured simultaneously at the same site using a combined non-invasive BF+OXY+temperature probe. Skin BF, oxygenated (oxyHb) and deoxygenated (deoxyHb) haemoglobin and mean oxygen saturation (SO2 ) were measured in 50 healthy volunteers at rest and during perturbation of local blood flow by post-occlusive reactive hyperaemia, sympathetic nervous system-mediated vasoconstriction (deep inspiratory breath-hold) and local skin warming. The relationship between BF and SO2 over the range of flows investigated was described by a non-linear equation with an asymptote for SO2 of 84% at BF >50 PU. SO2 was independently associated with BF, skin temperature, BMI and age, which together identified 59% of the variance in SO2 (p<0.0001). Fourier analysis revealed periodic low frequency fluctuations in both BF and SO2 , attributable to endothelial (~0.01 Hz), neurogenic (~0.04 Hz) and myogenic (~0.1Hz) flow motion activity. The frequency coherence between the BF and SO2 signals was greatest in the endothelial and neurogenic frequency bands. The simultaneous evaluation of microvascular blood flow and oxygenation kinetics in healthy skin provides a platform from which to investigate microvascular impairment in the skin and more generally the pathogenesis of microvascular disease. This article is protected by copyright. All rights reserved.
    Microcirculation (New York, N.Y.: 1994) 04/2014; DOI:10.1111/micc.12136 · 2.26 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Microcirculatory function can be assessed by post occlusive reactive hyperemia (PORH) using laser Doppler fluxmetry. Previous studies have shown that PORH reveals microvascular damage at an early stage. Especially at younger ages PORH might depend on age and gender. To implement PORH into a larger scale of clinical studies one has to be aware of the influence of age and gender on microcirculation. The aim of this study was to assess the impact of age and gender on microcirculatory function during adolescence.
    European Journal of Clinical Investigation 06/2014; 44(8). DOI:10.1111/eci.12293 · 2.83 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: New Findings• What is the central question of this study? Autonomic nervous dysfunction is implicated in complications of sickle cell anaemia (SCA). In healthy adults, a deep inspiratory breath hold (IBH) elicits rapid transient SNS‐ mediated vasoconstriction detectable using Laser Doppler Flux (LDF) assessment of the finger‐tip cutaneous micovasculature. • What is the main finding and its importance? We demonstrate significantly increased resting peripheral blood flow and sympathetic activity in African children with SCA compared to sibling controls and increased sympathetic stimulation in response to vasoprovocation with DIG.This study is the first to observe an inverse association between resting peripheral blood flow and haemoglobin oxygen saturation (SpO2). These phenomena may be an adaptive response to the hypoxic exposure in SCA.
    Experimental Physiology 01/2013; 98(1). DOI:10.1113/expphysiol.2011.064055 · 2.87 Impact Factor