Reduced flow-and acetylcholine-induced dilations in visceral compared to subcutaneous adipose arterioles in human morbid obesity.

BACKGROUND AND AIMS: The hypothesis of this study was that microvascular FID and AChID is impaired in visceral (VAT) compared to SAT arterioles in morbidly obese women. An Additional aim was to determine the mechanisms contributing to FID and AChID in VAT and SAT arterioles. METHODS AND RESULTS: Arterioles were obtained from SAT and VAT biopsies from women (BMI > 35 kg/m(2) ) undergoing bariatric surgery. Microvessels were cannulated for reactivity measurements in response to flow (pressure gradients of 10-100 cmH2 O) and to ACh (10(-9) -10(-4 ) M) with and without l-NAME, INDO, and PEG-catalase. NO and H2 O2 generation were detected in arterioles by fluorescence microscopy. FID and AChID of arterioles from VAT were reduced compared to SAT arterioles. In SAT arterioles, l-NAME, INDO, and PEG-catalase significantly reduced FID and AChID but had no effect individually on VAT arterioles' vasodilator reactivity. INDO +l-NAME reduced FID in VAT arterioles. NO-fluorescence was greater in arterioles from SAT compared to VAT arterioles. Vascular H2 O2 generation during flow was similar in both VAT and SAT. CONCLUSION: Our results suggest that VAT arterioles display reduced vasodilator reactivity to flow and ACh compared to SAT arterioles, mediated by different regulatory mechanisms in human obesity.

Apolipoprotein E enhances endothelial-NO production by modulating caveolin 1 interaction with endothelial NO synthase.

Apolipoprotein E (apoE) is widely expressed in mammalian tissues, and one of the important tissue-specific effects is the atheroprotection ascribed to macrophage-derived apoE in the arterial wall. However, underlying mechanisms are not well understood. In this study, using subcellular fractionation, confocal microscopy, and coimmunoprecipitation, we demonstrated that macrophage-derived apoE is internalized by endothelial cells and impacts the subcellular distribution/interaction of caveolin 1 (cav-1) and endothelial NO synthase (eNOS). The addition of apoE disrupts the heteromeric complex formed between cav-1 and eNOS, and increases NO production. Sterol and oxysterol enhance endothelial cav-1/eNOS interaction and suppress NO production, but these effects are reversed by apoE. Silencing endothelial cav-1 attenuates apoE-induced NO production, establishing the importance of the cav-1-eNOS interaction for the increment in endothelial NO produced by apoE. Consistent with these observations, macrophage-derived apoE significantly improves vasodilation to acetylcholine in resistance arteries isolated from adipose tissue of obese humans. We conclude that macrophage-derived apoE enhances endothelial NO production by disrupting the inhibitory interaction of eNOS with cav-1. These results establish a novel mechanism by which apoE modulates endothelial cell function.

Influence of short-term changes in sex hormones on serum concentrations of cellular adhesion molecules in young healthy women.

AIM: To determine if short-term changes in sex hormones (such as cyclic changes within the menstrual cycle) can influence the serum concentration of soluble cell adhesion molecules (CAMs). METHODS: Sixteen healthy young women with normal cycles participated in this study. Serum levels of sICAM-1, sVCAM-1 and E-selectin were determined in three different phases of the menstrual cycle: a) early follicular (EF) phase, b) ovulatory (O) phase and c) midluteal (ML) phase, by standardized ELISA-based kits. To confirm the exact assessment of menstrual cycle phases, serum levels of estrogen, progesterone, LH and FSH were measured. RESULTS: There were significant oscillations in serum female sex hormones concentration over the cycle duration, as expected the level of estrogen (E2) and progesterone (PROG) was the lowest in EF phase, the highest E2 appeared in O phase, and both E2 and PROG were present in high concentrations during ML phase. There was a significant positive correlation between E2 and serum soluble ICAM -1 concentrations (p=0,041, correlation coefficient 0,306). However, there was no significant change in other soluble CAMs concentration during the menstrual cycle. CONCLUSIONS: Results of our study suggest that short-term changes in female sex hormone levels could modulate expression of soluble ICAM-1, but not VCAM -1 or E-selectin in extent that would affect a young woman's health.