Metabolic disturbances linked to obesity: the role of impaired tissue perfusion

Abstract

Associated with elevated risk of cardiovascular events and cancer, obesity is a worldwide problem affecting developed and developing countries. Microcirculatory vessels, represented by arterioles, capillaries and venules (mean internal diameter < 100 µm), are the place where blood/tissue nutrition and exchange effectively take place. Microvascular dysfunction is an early event in obesity probably secondary to endothelial dysfunction and capillaries rarefaction. New research techniques allow the investigation of the microcirculation in different vascular beds in humans. Studies suggest a link between endothelial dysfunction and visceral obesity. Oxidative stress, inflammation and rennin-angiotensin system are among factors considered to be involved on microvascular dysfunction in obesity. Microcirculatory impairment present in obesity suggests that it could be an important causal factor in obesity-related disorders such as insulin resistance and hypertension. Arq Bras Endocrinol Metab. 2009;53(2):238-245. KeywordsObesity; endothelial dysfunction; microcirculation; tissue perfusion; metabolic syndrome ReSumoAssociada ao aumento do risco de eventos cardiovasculares e ao câncer, a obesidade é um problema mundial, que atinge tanto países desenvolvidos quanto em desenvolvimento. A microcirculação é composta por arteríolas, capilares e vênulas (diâmetro interno médio < 100 µm) e é o local onde ocorrem a oferta de nutrientes e as trocas entre o tecido e o sangue. A disfunção microcirculatória é um evento precoce na obesidade e este pode ser secundário à disfunção endotelial ou à redução no número de capilares (rarefação capilar). Novas técnicas em pesquisa permitem a avaliação da microcirculação em diferentes leitos vasculares em humanos. Estudos sugerem uma correlação entre disfunção endotelial e obesidade visceral. Acredita-se que o estresse oxidativo, a inflamação e a atividade aumentada do sistema renina-angiotensina estão entre os fatores envolvidos nessa associação. O comprometimento microcirculatório presente na obesidade sugere que esse pode ser um fator causal importante nas desordens relacionadas com a obesidade, como resistência insulínica e hipertensão. Arq Bras Endocrinol Metab. 2009;53(2):238-245. Descritores

Effect of Type 2 Diabetes Mellitus and Diabetic Nephropathy on IgG Pharmacokinetics and Subcutaneous Bioavailability in the Rat

“…Obese subjects have lower fasting and post-prandial SC abdominal adipose tissue blood flow and basal adipose tissue blood flow is negatively correlated with BMI (53). Microvascular dysfunction represents an early event in obesity even in the absence of hypertension, hypercholesteremia, and hyperglycemia (54,55). Clinically, obese subjects have lower fasting and post-prandial SC abdominal adipose tissue blood flow and basal adipose tissue blood flow is negatively correlated with BMI (53).…”

“…Obesity is associated with decreased tissue perfusion due to endothelial dysfunction or decrease in capillary density (56). Adipose tissue blood flow at the SC site has been measured in clinical studies and found to be decreased; additionally, there are decreased capillaries with an increase in adipose tissue (53,55). Although the mechanism underlying the correlation between obesity and absorption cannot be determined in this study, based on the literature and our present results, obesity may be playing a role in the changes observed in the rate of SC absorption of hIgG in the present studies.…”

Inflammation as a Link between Obesity and Metabolic Syndrome

“…Endothelial and microvascular dysfunction are present in obese subjects and represent important factors in metabolic disturbances, since they could influence both vascular resistance and insulin-mediated glucose disposal, contributing to hypertension and insulin resistance in obesity [52, 53]. …”

The endothelium in diabetes: Its role in insulin access and diabetic complications

“…The retina, peripheral nerves and kidney are particularly susceptible to defects in vascular function associated with diabetes, and lead to diabetic complications. Often, capillary rarefaction is observed, which can be either a functional or structural reduction in perfused capillaries[41]. Since blood supply is essential for nerve function, decreased microvascular effectiveness could contribute to diabetic neuropathy.…”