Ivana Grizelj

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.

Reduced Flow‐and Acetylcholine‐Induced Dilations in Visceral Compared to Subcutaneous Adipose Arterioles in Human Morbid Obesity

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.

Apolipoprotein E Enhances Endothelial-NO Production by Modulating Caveolin 1 Interaction With Endothelial NO SynthaseNovelty and Significance

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.

ApoE Enhances Endothelial- NO Production by Modulating Caveolin-1 Interaction with eNOS

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.

MECHANISMS OF PERIPHERAL TISSUE BLOOD FLOW INFLUENCED BY HIGH SALT DIET IN YOUNG HEALTHY FEMALE HUMAN SUBJECTS: PP.7.165

It is generally accepted that the high salt intake is an essential risk factor in development and progression of hypertension. Numerous studies have shown that endothelial dysfunction is an early manifestation of adverse effect of high salt loading. However, mechanisms by which high salt intake affect endothelium are still unknown. The Aim: of this study was to investigate the effect of acute salt loading and in particular the role of cyclooxygenase (COX 1, 2) in tissue blood flow regulation. Eleven healthy female medical students, volunteered to participate in this study. All participants maintained low salt diet (intake 200 mmol Na/day) and placebo (LS) group. Laser Doppler Flowmetry (LDF) was used to assess relative changes in peripheral tissue blood flow between baseline and reactive hyperemia, provoked by 1 minute (endothelium-mediated response) and 2 minute (effect of peak vasoactive metabolite release, maximal response) vascular occlusion. Participants were tested four times, before and after diet protocol, in basic conditions and 90 minutes after 100 mg of per oral indomethacin intake. 24 hour urine collection and venous blood sampling (plasma electrolytes, aldosterone and plasma renin activity (PRA)) were done before and after diet period. Results: of LDF measurements during basic conditions in HS group have shown statistically significant impairment in reperfusion tissue blood flow after 1 min occlusion, while after 2 min occlusion reperfusion blood flow was nearly the same before and after HS diet period. Indomethacin intake eliminated reduction in reperfusion blood flow in HS group. 24 hour urine sodium excretion was significantly higher in HS group and significantly lower in LS group. PRA and aldosterone levels decreased in HS and increased in LS group, as expected. The results of this study have shown that one week of high salt intake have caused impaired peripheral tissue blood flow that was restored to control condition after indomethacin intake. These observations suggest that vasoconstrictor metabolite of COX could play role in impaired tissue blood flow in subjects taking high salt diet for one week.