The Influence of Perivascular Adipose Tissue on Vascular Function in a Rabbit Model

Abstract

The recent acknowledgment of the paracrine role of perivascular adipose tissue (PVAT) in vascular modulation has been supported by many studies investigating major arteries in several animal models and humans. The influence of PVAT on the functional activity of the vascular bed has been a matter of debate, whether it is an anticontractile effect with protective roles or a pro-contractile effect, investigations are underway to address this obscurity. In this investigation, we have studied the effects of vasoconstrictors, phenylephrine and noradrenaline, and vasorelaxants, carbachol and s-nitroso-n- acetylpenicillamine (SNAP), on subclavian and iliac rings with and without PVAT attached; and concentration-response curves were constructed accordingly. Levels of nitric oxide (NO) generated due to activation of the enzyme adenosine monophosphate-activated protein kinase (AMPK) by 5-Aminoimi- dazole-4-carboxamide-1-β-D-ribofuranoside (AICAR) were measured in sub- clavian and iliac PVAT conditioned media. Additionally, Haematoxylin and Eosin staining was performed to analyze and compare the histological characteristics of both arteries. Subclavian and iliac rings with PVAT attached showed stronger contraction to phenylephrine and noradrenaline than that of rings without PVAT attached. At the same time, relaxation tests reported lower relaxation percentages in subclavian and iliac rings with PVAT attached compared to rings without PVAT attached in response to carbachol and SNAP. PVAT treated with AICAR generated higher levels of NO compared to levels of untreated PVAT. Conclusions drawn were the pro-contractile effects demonstrated by the PVAT especially in high concentrations of drugs used. In addition, histology analysis revealed characteristics of white adipose tissue in both PVATs.