Abstract
Perivascular adipose tissue (PVAT) can modulate vascular tone. Norepinephrine transport in PVAT may serve as a buffer system to reduce adrenergic activation of vascular contraction. We hypothesized that the norepinephrine transporter (NET) is present in PVAT and used the NET selective fluorescent dye 4‐(‐4‐(dimethylamino)‐styryl)‐N‐methylpyridinium (ASP+) to probe for NET in mesenteric PVAT from normal male Sprague Dawley rats. PVAT was incubated ex‐vivo with ASP+ and/or inhibitor and imaged by confocal microscopy. A concentration‐response curve for ASP+ staining of PVAT was constructed and used to select 2 μM as the optimum concentration. Vehicle‐incubated ASP+ signal was 137.5±8.6 AFU (arbitrary fluorescence units, n=18). Nisoxetine, a NET specific inhibitor, reduced ASP+ binding at 10 μm but not 100 nM [96.0±14.5 AFU and 115.9±4.1 AFU respectively (p<0.05; n=6‐7)]. Similarly, citalopram (100 nM), a specific serotonin transporter (SERT) inhibitor, reduced ASP+ binding to 97.7±14.5 AFU (p<0.05; n=11). ASP+ binding was not reduced by GBR 12935 (100 nM), a specific dopamine transporter specific inhibitor (138.0±8.6 AFU; n=12). These data suggest that SERT mediates monoamine uptake into PVAT. Dysfunction of the monoamine transport systems may in part explain altered vascular tone in hypertensive states.