Gender differences in microcirculation: Observation using the hamster cheek pouch

OBJECTIVES: Estrogen has been shown to play an important protective role in non-reproductive systems, such as the cardiovascular system. Our aim was to observe gender differences in vivo with regard to the increase in macromolecular permeability and leukocyte-endothelium interaction induced by ischemia/reperfusion as well as in microvascular reactivity to vasoactive substances using the hamster cheek pouch preparation. METHODS: Thirty-six male and 36 female hamsters, 21 weeks old, were selected for this study, and their cheek pouches were prepared for intravital microscopy. An increase in the macromolecular permeability of post-capillary venules was quantified as a leakage of intravenously injected fluorescein-labeled dextran, and the leukocyte-endothelium interaction was measured as the number of fluorescent rolling leukocytes or leukocytes adherent to the venular wall, labeled with rhodamin G, during reperfusion after 30 min of local ischemia. For microvascular reactivity, the mean internal diameter of arterioles was evaluated after the topical application of different concentrations of two vasoconstrictors, phenylephrine (α1-agonist) and endothelin-1, and two vasodilators, acetylcholine (endothelial-dependent) and sodium nitroprusside (endothelial-independent). RESULTS: The increase in macromolecular permeability induced by ischemia/reperfusion was significantly lower in females compared with males [19 (17-22) leaks/cm2 vs. 124 (123-128) leaks/cm2, respectively, p<0.001), but the number of rolling or adherent leukocytes was not different between the groups. Phenylephrine-induced arteriolar constriction was significantly lower in females compared with males [77 (73-102)% vs. 64 (55-69)%, p<0.04], but there were no detectable differences in endothelin-1-dependent vasoreactivity. Additionally, arteriolar vasodilatation elicited by acetylcholine or sodium nitroprusside did not differ between the groups. CONCLUSION: The ...

Efeitos do estradiol sobre a função endotelial, sensibilidade insulínica e viscosidade sanguínea em mulheres na pós-menopausa com excesso de peso / Effects of estradiol on endothelial function, insulin sensitivity and blood viscosity in overweight postmenopausal women

A ação que o estrogênio desempenha sobre o endotélio depende da integridade deste e consequentemente das características clínicas de cada indivíduo. O uso da terapia hormonal da menopausa (THM) em mulheres com baixo risco cardiovascular geralmente resulta em efeitos benéficos, desde que iniciado em um período próximo da menopausa. Em contrapartida, o seu uso em mulheres com alto risco cardiovascular, como diabéticas ou portadoras de lesões ateroscleróticas já estabelecidas, e ainda naquelas com início da THM em um período superior a dez anos da menopausa geralmente resulta em efeitos maléficos. Nosso objetivo é avaliar os efeitos do estrogênio sobre a função endotelial em mulheres com sobrepeso ou obesidade, ou seja, indivíduos com risco cardiovascular intermediário. Para isso, 44 mulheres na pós-menopausa com idade entre 47 a 55 anos e índice de massa corporal (IMC) de 27,5 a 34,9kg/m², foram randomizadas nos grupos placebo (P) e estrogênio transdérmico (ET). A intervenção consistiu no uso transdérmico de estradiol, 1mg por dia, por um período de três meses. As participantes realizaram avaliação da reatividade endotelial em repouso e após isquemia [pletismografia por oclusão venosa (POV), com medidas do fluxo sanguíneo do antebraço (FSA) e videocapilaroscopia dinâmica do leito periungueal (VCLP), com medidas da velocidade de deslocamento das hemácias (VDH)], dosagens de moléculas de adesão [E-selectina, molécula de adesão intercelular (ICAM-1) e molécula de adesão vascular (VCAM-1)], aferição da sensibilidade insulínica [através do homeostatic model assessment of insulin resistance (HOMA-IR) e área sob a curva (AUC) da insulina durante o teste oral de tolerância à glicose (TOTG)] e mensurações das viscosidades sanguínea e plasmática. As participantes apresentaram idade de 51,77 ± 2,3 anos, IMC de 31,52 ± 2,54 kg/m² e tempo de menopausa de 3 [2-5] anos. O grupo P não apresentou nenhuma mudança significativa em qualquer variável. Após a intervenção, o grupo ...

The action that estrogen plays on the endothelium depends on its integrity and consequently on the clinical characteristics of each individual. The use of menopausal hormone therapy (MHT) in women with low cardiovascular risk usually results in beneficial effects, since it is started in a period close to menopause. In contrast, its use often results in harmful effects in women at high cardiovascular risk, such as diabetic ones or those with established atherosclerotic lesions, and even in those that the beginning of MHT exceeds ten years from menopause. Our goal is to evaluate the effects of estrogen on endothelial function in overweight women, ie, individuals at intermediate cardiovascular risk. For this purpose, 44 postmenopausal women, aged 47-55 years with body mass index (BMI) from 27.5 to 34.9 kg / m², were randomized into placebo (P) and transdermal estrogen (TE) groups. The intervention consisted of using transdermal estradiol 1mg per day for a period of three months. Participants underwent endothelial reactivity assessment at rest and after ischemia [by venous occlusion plethysmography (VOP), with assessment of forearm blood flow (FBF) and dynamic nailfold videocapillaroscopy (DNV), with assessment of red blood cell velocity (RBCV)], measurements of soluble adhesion molecules [E-selectin, intercellular adhesion molecule (ICAM-1) and vascular cell adhesion molecule (VCAM-1)], measurement of insulin sensitivity [by homeostatic model assessment of insulin resistance (HOMA-IR) and area under the curve (AUC) of insulin during the oral glucose tolerance test (OGTT)] and measurements of blood and plasma viscosities. The participants aged 51.77 ± 2.3 years, BMI 31.52 ± 2.54 kg/m² and had a time since menopause of 3 [2-5] years. P group showed no significant change in any variable. After intervention, the TE group compared to the baseline presented in DNV lower time taken to reach RBCV during post-occlusive reactive hyperemia (PORH) (4,0 [3,25-5,0] vs. 5,0 ...