Abstract 307: The Presence of an Adrenergic System in Perivascular Adipose Tissue

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Abstract

Perivascular adipose tissue (PVAT) is under recognized for its importance in blood pressure regulation. Visceral adipocytes reportedly contain catecholamines. Adipocytes in PVAT are directly adjacent to the blood vessels they surround and therefore the production, release and/or reuptake of catecholamines may significantly affect vascular tone. We hypothesize that an adrenergic system is present in PVAT. Glyoxylic acid staining revealed the presence of catecholamines in the cytosol of mesenteric PVAT adipocytes. Dopamine (DA), norepinephrine (NE) and epinephrine were quantified by HPLC in rat aortic PVAT, brown fat, mesenteric PVAT and retroperitoneal fat with NE being the most abundant at concentrations of 731.9, 815.0, 668.7 and 73.2 ng/g from each tissue, respectively. Two key enzymes in catecholamine synthesis; tyrosine hydroxylase and dopamine β-hydroxylase, were located to PVAT adipocytes by immunohistochemistry. The norepinephrine transporter (NET) was detected on mesenteric PVAT adipocytes by confocal microscopy using ASP+ (2μM), a fluorescent NET substrate. Uptake of ASP+ was blocked by the NET specific inhibitor nisoxetine (10μM) (see figure). These data show that PVAT contains all of the elements of an adrenergic system and may contribute to vascular and adipose function in health and disease.

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