Ana Čavka

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.

Adrenergic System Activation Mediates Changes in Cardiovascular and Psychomotoric Reactions in Young Individuals after Red Bull© Energy Drink Consumption

Objectives. To assess the effect of Red Bull© on (1) blood glucose and catecholamine levels, (2) cardiovascular and respiratory function changes before, during, and after exercise, (3) reaction time, (4) cognitive functions, and (5) response to mental stress test and emotions in young healthy individuals (N=38). Methods. Heart rate (HR) and arterial blood pressure (ABP), blood glucose, adrenaline, and noradrenalin plasma levels were measured before and after Red Bull© intake. Participants were subjected to 4 different study protocols by randomized order, before and 30 minutes after consumption of 500 mL of Red Bull©. Results. Mean ABP and HR were significantly increased at rest after Red Bull© intake. Blood glucose level and plasma catecholamine levels significantly increased after Red Bull© consumption. Heart rate, respiration rate, and respiratory flow rate were significantly increased during exercise after Red Bull© consumption compared to control condition. Intake of Red Bull© significantly improved reaction time, performance in immediate memory test, verbal fluency, and subjects attention as well as performance in mental stress test. Conclusion. This study demonstrated that Red Bull© has beneficial effect on some cognitive functions and effect on cardiovascular and respiratory system at rest and during exercise by increasing activity of the sympathetic nervous system.

7D.04: ACUTE SALT LOADING AFFECTS VASCULAR FUNCTION WITHOUT SIGNIFICANT CHANGE IN BODY FLUID STATUS AND BODY COMPOSITION IN YOUNG HEALTHY WOMEN.

Objective: Our previous study demonstrated that one week of salt loading significantly impaired skin microvascular reactivity without changes in blood pressure (BP) levels. The aim of this study was to evaluate whether one week of high-salt (HS) diet changes body fluid status and body composition subsequently affecting vascular reactivity. Design and method: 10 healthy women (age range 20–23) took a 7-days low-salt (LS) diet (<40mmol Na/day) and 7-days HS diet (∼240mmol of Na/day). Salt resistance, defined as a <5 mmHg change in BP determined while on the LS and HS diets was confirmed in all subjects. Skin microvascular post occlusive reactive hyperemic (PORH) blood flow (indicator of endothelial function) was assessed by laser Doppler flowmetry (LDF) before and after each diet protocol. Plasma Renin Activity (PRA), plasma aldosterone, plasma and 24h-urine sodium, potassium, urea and creatinine levels were measured before and after diets. Body composition was assessed with a four-terminal portable impedance analyzer (Maltron Bioscan 920-II). Body Mass Index (BMI), Fat Free Mass% (FFM%), Fat Mass% (FM%), Total Body Water% (TBW%), Extracellular Water% (ECW%), Intracellular Water (ICW%), ECW/ICW, Plasma Fluid (PF), Interstitial Fluid (IF) and Body Density Mass (BDM) were calculated. Results: Changes in 24 h urinary sodium, PRA and plasma aldosterone levels confirmed subjects conformed to the diet. There was no change in BP and HR before and after both diet protocols. HS diet caused significant impairment in microvascular reactivity (PORH) (R-O LS diet 156 ± 23% vs. HS diet 100 ± 12%, P = 0.040). One week HS diet did not induce any significant change in body composition parameters BMI, FFM%, FM% and BDM, compared to LS diet. Body fluid components (TBW%, ECW%, ICW%, ECW/ICW, PF and IF) were not different in LS compared to HS group. Conclusions: This study confirmed that even one week of HS diet significantly altered microvascular reactivity in young healthy normotensive and salt-resistant women, without changes in BP. Furthermore, our results indicate that vascular changes after HS diet are independent of body composition and body fluid status just as they are pressure independent, but are consequence of unique effect of HS on endothelial function.

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.