Regulation of rat thoracic aortic tone by perivascular adipose tissue is endothelium-dependent

Abstract

The perivascular adipose tissue (PVAT) is associated with the artery wall, which enables diffusion of reactive oxygen species and cytokines and are capable of inducing endothelial dysfunction and enhancing vasoconstriction in vessels. In this study, adult male Wistar rats weighing 265–305 g were euthanatized by intravenous injection of overdose of sodium pentobarbital. The thoracic aortas were isolated, dissected without the PVAT, divided into endothelium-intact and endothelium-denuded groups, and mounted in organ bath containing a Krebs’ solution bubbled with 95% O 2 and 5% CO 2 at 37°C. PVAT was incubated in Krebs’ solution for 30 min before the isometric tension studies. The phenylephrine (PE) and acetylcholine (ACh) dose–response curves were performed to examine the vascular reactivity and endothelial function, respectively. Our results showed that in the presence of PVAT (transferred from incubated bath to experimental bath), the PE-induced contraction was enhanced and the ACh-elicited relaxation was impaired in the endothelium-intact group. However, these results were not reproduced in the endothelium-denuded or pretreatment with L-NAME groups. According to these results, we hypothesized that PVAT regulated aortic tones in an endothelial nitric oxide synthase (eNOS)-dependent manner. There are many well-known factors which inhibited eNOS activity directly, including caveolin-1 (Cav-1). Our results demonstrated that protein expression of Cav-1 in aorta was significant increased when PVAT was present. In conclusion, the factors released from PVAT regulate the rat aortic tones and their actions are, at least, mediated by the endothelium.