Vasoactive effects of prostaglandins from the perivascular fat of mesenteric resistance arteries in WKY and SHROB rats

Aims: We have studied the vasoactive role of prostaglandins derived from perivascular adipose tissue (PVAT) and their effects on endothelial function in healthy rats and rats with metabolic syndrome (SHRUB). Main methods: Mesenteric resistance arteries (MRA) from SHRUB and control rats (WKY) were mounted on wire myographs: a) together with a sphere of naturally occurring perivascular adipose tissue (with-PVAT group), orb) dissecting all the adventitial tissue (without-PVAT group). Key findings: Endothelial function, tested by acetylcholine reactivity of SHRUB arteries with PVAT, was significantly lower than that of WKY. With-PVAT arteries, especially the SHRUB, showed lower responses than those without PVAT. NO synthase inhibition diminished the acetylcholine responses in every group except the with-PVAT SHROB group. Blockade of cyclooxygenase-2, PGI(2)-IP, TXA(2)-TP, or TXA(2) synthase increased to different extents the arterial responses in the SHRUB with-PVAT group. PVAT from both rat strains revealed cyclooxygenase-2 activity and immunoassay confirmed the release of PGE(2), PGI(2) and TXA(2). Significance: Our major finding is that PVAT is a source of vasoactive prostaglandins in WKY and SHRUB. We also report that the presence of visceral PVAT causes endothelial dysfunction of resistance arteries in the SHRUB. The vascular responses to prostaglandins partly underlie the endothelial dysfunction of SHRUB arteries. (C) 2013 Elsevier Inc. All rights reserved.