scholarly journals Perivascular adipose tissue: A new possible tissue augmenting coronary vasodilatation in response to acute hypoxia

2018 ◽  
Vol 224 (4) ◽  
pp. e13171 ◽  
Author(s):  
Ulf Simonsen ◽  
Asbjørn G. Petersen
Author(s):  
Sophie N Saxton ◽  
Lauren K Toms ◽  
Robert G Aldous ◽  
Sarah B Withers ◽  
Jacqueline Ohanian ◽  
...  

AbstractPurposePerivascular adipose tissue (PVAT) exerts an anti-contractile effect which is vital in regulating vascular tone. This effect is mediated via sympathetic nervous stimulation of PVAT by a mechanism which involves noradrenaline uptake through organic cation transporter 3 (OCT3) and β3-adrenoceptor-mediated adiponectin release. In obesity, autonomic dysfunction occurs, which may result in a loss of PVAT function and subsequent vascular disease. Accordingly, we have investigated abnormalities in obese PVAT, and the potential for exercise in restoring function.MethodsVascular contractility to electrical field stimulation (EFS) was assessed ex vivo in the presence of pharmacological tools in ±PVAT vessels from obese and exercised obese mice. Immunohistochemistry was used to detect changes in expression of β3-adrenoceptors, OCT3 and tumour necrosis factor-α (TNFα) in PVAT.ResultsHigh fat feeding induced hypertension, hyperglycaemia, and hyperinsulinaemia, which was reversed using exercise, independent of weight loss. Obesity induced a loss of the PVAT anti-contractile effect, which could not be restored via β3-adrenoceptor activation. Moreover, adiponectin no longer exerts vasodilation. Additionally, exercise reversed PVAT dysfunction in obesity by reducing inflammation of PVAT and increasing β3-adrenoceptor and OCT3 expression, which were downregulated in obesity. Furthermore, the vasodilator effects of adiponectin were restored.ConclusionLoss of neutrally mediated PVAT anti-contractile function in obesity will contribute to the development of hypertension and type II diabetes. Exercise training will restore function and treat the vascular complications of obesity.


2021 ◽  
Vol 22 (5) ◽  
pp. 2649
Author(s):  
Alexis N. Orr ◽  
Janice M. Thompson ◽  
Janae M. Lyttle ◽  
Stephanie W. Watts

Transglutaminases (TGs) are crosslinking enzymes best known for their vascular remodeling in hypertension. They require calcium to form an isopeptide bond, connecting a glutamine to a protein bound lysine residue or a free amine donor such as norepinephrine (NE) or serotonin (5-HT). We discovered that perivascular adipose tissue (PVAT) contains significant amounts of these amines, making PVAT an ideal model to test interactions of amines and TGs. We hypothesized that transglutaminases are active in PVAT. Real time RT-PCR determined that Sprague Dawley rat aortic, superior mesenteric artery (SMA), and mesenteric resistance vessel (MR) PVATs express TG2 and blood coagulation Factor-XIII (FXIII) mRNA. Consistent with this, immunohistochemical analyses support that these PVATs all express TG2 and FXIII protein. The activity of TG2 and FXIII was investigated in tissue sections using substrate peptides that label active TGs when in a catalyzing calcium solution. Both TG2 and FXIII were active in rat aortic PVAT, SMAPVAT, and MRPVAT. Western blot analysis determined that the known TG inhibitor cystamine reduced incorporation of experimentally added amine donor 5-(biotinamido)pentylamine (BAP) into MRPVAT. Finally, experimentally added NE competitively inhibited incorporation of BAP into MRPVAT adipocytes. Further studies to determine the identity of amidated proteins will give insight into how these enzymes contribute to functions of PVAT and, ultimately, blood pressure.


2021 ◽  
Author(s):  
Anthony R. Angueira ◽  
Alexander P. Sakers ◽  
Corey D. Holman ◽  
Lan Cheng ◽  
Michelangella N. Arbocco ◽  
...  

Cells ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1485
Author(s):  
Adrian Sowka ◽  
Pawel Dobrzyn

Studies of adipose tissue biology have demonstrated that adipose tissue should be considered as both passive, energy-storing tissue and an endocrine organ because of the secretion of adipose-specific factors, called adipokines. Adiponectin is a well-described homeostatic adipokine with metabolic properties. It regulates whole-body energy status through the induction of fatty acid oxidation and glucose uptake. Adiponectin also has anti-inflammatory and antidiabetic properties, making it an interesting subject of biomedical studies. Perivascular adipose tissue (PVAT) is a fat depot that is conterminous to the vascular wall and acts on it in a paracrine manner through adipokine secretion. PVAT-derived adiponectin can act on the vascular wall through endothelial cells and vascular smooth muscle cells. The present review describes adiponectin’s structure, receptors, and main signaling pathways. We further discuss recent studies of the extent and nature of crosstalk between PVAT-derived adiponectin and endothelial cells, vascular smooth muscle cells, and atherosclerotic plaques. Furthermore, we argue whether adiponectin and its receptors may be considered putative therapeutic targets.


Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Kaivan Khavandi ◽  
Adam Greenstein ◽  
Sarah Withers ◽  
Kazuhiko Sonoyama ◽  
Sarah Lewis ◽  
...  

In order to investigate the contribution of perivascular adipose tissue (PVAT) to arterial function, a total of 55 small arteries harvested from 35 skin biopsies of patients with Metabolic Syndrome and matched controls were mounted as ring preparations in a wire myograph. Contractility to cumulative doses of Norepinephrine in the presence or absence of PVAT showed an anticontractile effect in arteries from healthy volunteers (p=0.009), which was lost in patients with Metabolic Syndrome. Bioassay studies confirmed that PVAT releases a hydrophilic anticontractile factor in health, which is absent in obesity. Using a soluble fragment of the human Type 1 receptor, we identified that the anticontractile factor was adiponectin, which is the sole mediator of vasodilation, acting by increasing endothelial bioavailability of nitric oxide. Significant endothelial dysfunction was observed in patients with Metabolic Syndrome (p<0.001). Quantitative image analysis of adipose tissue revealed significantly increased adipocyte cell size in patients with Metabolic Syndrome, compared with healthy controls (p<0.006). There was immunohistochemical evidence of inflammation with upregulation of TNF-alpha receptor 1 in these patients (p<0.001). Application of exogenous TNF-alpha abolished the anticontractile effect of PVAT by reducing adiponectin bioavailability. Oxidative stress also induced by cytokines TNF-alpha and IL-6 but not IL-1, reduced adiponectin production from PVAT and increased basal tone. When the obese microenvironment was replicated in vitro by inflicting hypoxia on PVAT, adiponectin activity was lost but then rescued by incubation with cytokine antagonists. Further application of the adiponectin receptor fragment abolished PVAT relaxation. We conclude that in healthy arteries, PVAT releases adiponectin which reduces vascular tone. In obesity, this is lost by a cascade of adipocyte hypertrophy, hypoxia, inflammation and oxidative stress. The resulting vasoconstriction contributes to hypertension, hypertriglyceridaemia and insulin resistance. Direct targeting of adiponectin release from PVAT therefore provides a novel therapeutic opportunity in the Metabolic Syndrome.


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