Marcadores de função endotelial no hipotireoidismo

Abstract

RESUMOO papel do endotélio em várias doenças vem sendo o foco da investigação científica e recentemente estão disponíveis métodos de avaliação da função endotelial de menor custo e menos invasivos. O endotélio modula o tônus vascular, participa dos processos inflamatórios, da ativação de plaquetas e da trombose. Consequentemente, a disfunção endotelial tem sido considerada evento importante na patogênese da aterosclerose. O hipotireoidismo está associado a maior risco cardiovascular, e a avaliação da função endotelial vem sendo reconhecida como ferramenta promissora na detecção de alterações cardiovasculares pré-clínicas associadas à disfunção tireoidiana. Alguns estudos recentes demonstraram relação entre o status tireoidiano e a função endotelial. Entretanto, estudos multicêntricos e controlados por placebo são necessários para abordar essa questão e o efeito da reposição da levotiroxina na função endotelial. Esse artigo propõe-se a discutir as perspectivas da relação entre endotélio e função tireoidiana. Arq Bras Endocrinol Metab. 2009;53(3):303-9. DescritoresHipotireoidismo; endotélio; aterosclerose; dilatação fluxo-mediada ABSTRACTThe role of the endothelium in human disease has become the focus of scientific investigation and recently noninvasive and less expensive measures of endothelial function have become available. The endothelium modulates the vascular tonus and participates in inflammatory processes, platelet aggregation and thrombosis. Consequently, endothelial dysfunction has been implicated as an important event in the pathogenesis of atherosclerosis. Hypothyroidism is associated with an increased cardiovascular risk, and the assessment of endothelial function holds a great deal of promise as an assessment tool for the detection of preclinical cardiovascular alterations associated with thyroid dysfunction. Some recent studies have demonstrated a relationship between thyroid status and endothelial function, but large multicenter, placebo-controlled prospective trials are necessary to address this issue and the effect of levothyroxine replacement treatment in endothelial function. The objective of this work is to discuss the perspective picture in endothelium and thyroid function relationship. Arq Bras Endocrinol Metab. 2009;53(3):303-9.

Aerobic Exercise and Endothelium

“…Cabral et al (14) complement that endothelial cells have channels of membrane ions, such as calcium and potassium, which respond to shear stress releasing nitric oxide in the amount proportional to the velocity of blood flow. NO is responsible for 70% of vasodilation, being formed from the enzyme endothelial nitric oxide synthase (eNOS) which converts the substrates oxygen and L-arginine to nitric oxide and L-citrulline (1,14) .…”

“…NO is responsible for 70% of vasodilation, being formed from the enzyme endothelial nitric oxide synthase (eNOS) which converts the substrates oxygen and L-arginine to nitric oxide and L-citrulline (1,14) . Dias et al (8) complement that it is a gaseous molecule, presenting as a free radical, since in its structural form it presents an unpaired electron in the last layer and a half-life of 4 to 8 seconds in oxygenated aqueous medium.…”

“…Endothelial damage may be linked to several risk factors, such as advanced age, heart failure, hypertension, obesity, hypercholesterolemia, diabetes, smoking, sedentary lifestyle, free radicals, among others, resulting in alterations in vessel homeostasis, leading to a reduced vasodilation dependent endothelium, vascular hyper reactivity (vessel spasms), increased local cell adhesion, thrombus formation and vessel occlusion (14,16) . It has been implicated in the pathogenesis of diabetic vascular disease and metabolic syndrome, as well as in low insulin sensitivity, dyslipidemia, hypertension, and also among active and passive smokers, leading to a common final pathway to cardiovascular diseases (17) .…”

“…It has been implicated in the pathogenesis of diabetic vascular disease and metabolic syndrome, as well as in low insulin sensitivity, dyslipidemia, hypertension, and also among active and passive smokers, leading to a common final pathway to cardiovascular diseases (17) . Endothelial dysfunction appears early in the progression of atherosclerosis, in which endothelial cells are the first to be exposed to inflammatory processes and disease, and consequently can lead to changes in vascular tone, thrombotic dysfunctions, proliferation and migration of smooth muscle cells (CML) and leukocyte adhesion, besides producing reactive oxygen species (ROS), which are responsible for reducing the bioavailability of nitric oxide (1,14,18) . Cabral et al (14) add that endothelial cell damage, potentiates the release of endothelin-1, a pro-inflammatory peptide and potent vasoconstrictor of large and small vessels.…”

“…Endothelial dysfunction appears early in the progression of atherosclerosis, in which endothelial cells are the first to be exposed to inflammatory processes and disease, and consequently can lead to changes in vascular tone, thrombotic dysfunctions, proliferation and migration of smooth muscle cells (CML) and leukocyte adhesion, besides producing reactive oxygen species (ROS), which are responsible for reducing the bioavailability of nitric oxide (1,14,18) . Cabral et al (14) add that endothelial cell damage, potentiates the release of endothelin-1, a pro-inflammatory peptide and potent vasoconstrictor of large and small vessels. Endothelium function can be evaluated in a variety of ways through invasive or non-invasive methods, which may involve venous or arterial endothelium.…”