Importance of Skin Microvasculature and Alterations of Skin Microcirculation in Obesity

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Adipose tissue receives a rich capillary blood supply. Capillary rarefaction and increased vasoconstrictor response to local cooling in the human skin has been demonstrated in individuals with essential hypertension [7, 8]. Alterations in skeletal muscle microvascular function are paralleled by alterations in skin microvascular function in hypertensive humans [9]. Sympathetic control of skin blood flow is reduced in obesity [10]. Even young children with obesity have morphologic alterations in skin microvasculature, such as increased number of tortuous loops in finger nailfold capillaries. Obese children have also been shown to have decreased capillary blood cell velocity after a 1-minute arterial occlusion [11]. These children's blood flow response to 1-minute arterial occlusion, as measured by laser-Doppler flowmetry, was not altered. This could represent shunting of blood from capillaries through arteriovenous anastomoses. Increased arteriovenous shunting of blood in human skin has also been demonstrated in diabetes [2]. Obesity precedes insulin resistance and diabetes, and these early changes in skin microvascular morphology and reactivity demonstrated by Chin et al. could be precursors of microvascular changes leading to the development of skin ulcers with the development of diabetes.

Individuals with impaired glucose tolerance have been shown to have blunted vasodilatory response to local skin heating. This abnormality was found to be associated with elevated fasting plasma insulin concentration, but not with fasting plasma glucose [12]. The mechanisms responsible for the association between defective skin microvascular hyperemic response and insulin resistance remain to be elucidated. Body mass index has a significant inverse correlation with endothelium-dependent skin vasodilatation [13]. Normotensive obese subjects exhibit deficient skin micro-circulatory vasodilatation to mental stress. There is evidence that subcutaneous adipose tissue blood flow contributes significantly to total forearm blood flow. Mental stress causes an increase in skin sympathetic nerve activity and cutaneous vasodilatation in the normal range of skin temperatures. This is consistent with a predominant b-adrenoreceptor-mediated vasodilatation. Cardiopulmonary baroreceptor unloading leads to skin vasoconstriction, which demonstrates that skin microvasculature plays a role in regulation of systemic vascular resistance and blood pressure. Recently, our group demonstrated that deficient skin as well as whole-forearm vasodilatation occurs after mental stress in obese normotensive subjects (Figure 1). Deficient skin vasodilatation in conjunction with increased cardiac output in response to psychosocial stress may account for the development of hypertension and cardiovascular disease in obesity.







Figure 1 (A) Skin blood flow and (B) skin vascular resistance percent changes from baseline during mental stress in obese and lean subjects. SBF, skin blood flow; SVR, skin vascular resistance. *P < 0.05 versus baseline. |P < 0.05 versus lean subjects. n = 11.

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Diabetes 2

Diabetes 2

Diabetes is a disease that affects the way your body uses food. Normally, your body converts sugars, starches and other foods into a form of sugar called glucose. Your body uses glucose for fuel. The cells receive the glucose through the bloodstream. They then use insulin a hormone made by the pancreas to absorb the glucose, convert it into energy, and either use it or store it for later use. Learn more...

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