Perivascular Adipocytes Store Norepinephrine by Vesicular Transport

Abstract

Perivascular adipose tissue (PVAT) exerts an anti‐contractile effect on blood vessels in healthy individuals, a mechanism lost in obesity‐related hypertension. To understand this process, we must first investigate the role of the functional adrenergic system residing within PVAT. We have shown that PVAT contains functional norepinephrine (NE), and that PVAT adipocytes have NE transporters, similar to sympathetic neurons. We hypothesize that NE is stored in vesicles within PVAT adipocytes, and that the vesicular monoamine transporter (VMAT) is used to do so. High‐performance liquid chromatography showed the presence of NE in normal male Sprague Dawley rat superior mesenteric artery (SMPVAT; 503.60 ± 34.70 ng/g tissue) and mesenteric (MPVAT; 148.20 ± 15.00 ng/g tissue) PVATs (N=6). Using immunofluorescence, we tested for VMAT1 and VMAT2 in these PVATs (N=6), and both transporters were present surrounding the lipid of the adipocytes. Immunofluorescence of MPVAT (N=4) and SMPVAT (N=4) revealed the co‐localization of NE and VMAT2 surrounding the lipid of PVAT adipocytes, and especially concentrated around the nucleus. We developed a protocol imaging live primary rat MPVAT adipocytes to capture real‐time uptake of Mini202, a fluorescent VMAT probe functioning as a false neurotransmitter (N=4). Cells were stained with 500 μM Mini202 (see data table). Addition of Rose Bengal (100 μM), a potent VMAT inhibitor, significantly reduced Mini202 signal. Addition of plasma membrane transporter inhibitors, nisoxetine (NE transporter, 10 mM) and corticosterone (organic cation 3 transporter, 10 mM) also significantly reduced Mini202 signal. Interestingly, immunofluorescence results support that neither VMAT1 (N=4) nor VMAT2 (N=4) is present in retroperitoneal adipocytes, suggesting that perivascular adipocytes are unique in their ability to store NE. This study supports a new function of perivascular adipocytes in storing amines and provides a basis for understanding NE storage by PVAT in obesity‐related hypertension.Support or Funding InformationFunding provided by NIH NHLBI PO1HL70687 and the APS UGREFThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.