Abstract P061: Identification Of Piezo1 Channels In Perivascular Adipose Tissue (pvat) And Their Potential Role In Vascular Function

Abstract

The vasculature constantly experiences distension/pressure exerted by the blood and responds accordingly to maintain homeostasis. Perivascular adipose tissue (PVAT) is gaining support as a formal blood vessel layer and also experiences these changes. We hypothesized that activation of the mechanotransducer Piezo1 directly increases vascular contraction in a way that might be modified by PVAT. The presence of Piezo1 was investigated at the mRNA level via PCR; protein via immunohistochemistry; and contractility via isolated tissue bath. Rat superior and mesenteric arteries, thoracic aortae, human mesenteric vessels and their PVATs were studied. Piezo1 mRNA (beta2 microglobulin calibrator) was expressed in the aortic vessel (2 -ΔC T =0.011); aortic PVAT (2 -ΔC T =0.0172); mesenteric vessel (2 -ΔC T =.00302), and mesenteric PVAT (2 -ΔC T =0.0219). Both adipocytes (2 -ΔC T =0.0249) and stromal vascular fraction (2 -ΔC T =0.0159) of mesenteric PVAT expressed Piezo1 mRNA. Piezo1 mRNA expression was greater in magnitude (one-way ANOVA) than that of the mechanotransducers Piezo2, TRPV4, TMEM16, and Panx1. Piezo1 protein was present in rat aortic PVAT, rat mesenteric (mes) artery, vein, and PVAT, as well as in human artery, vein, and PVAT. The Piezo1 agonists Yoda and Jedi (1 nM - 10 μM) did not stimulate rat aortic contraction [max <10% phenylephrine (PE) 10 μM contraction] or relaxation independent from vehicle in tissues + or - PVAT (relaxation as % of half maximal PE contraction was: Veh-PVAT=45.3±7.0; Yoda-PVAT=46.7±25.6; Jedi-PVAT= 40.4±10.3; Veh+PVAT= 71.8±19.7; Jedi+PVAT=39.1±13.2; Yoda +PVAT=21.6±10.9). Slightly K+ depolarizing the aorta did not unmask contraction to Yoda. Finally, the Piezo1 antagonist Dooku [10 μM] did not shift the PE curve (-log EC50 values [M]: Veh-PVAT= 7.96±0.12; Dooku-PVAT=7.26±0.22, Veh+PVAT=7.29±0.08; Dooku+PVAT=6.96±0.07). Surprisingly, Dooku [10 μM] directly caused aortic contraction in the absence of PVAT (Dooku 27.2±11.7 vs vehicle 13.5±11.2 %PE contraction), but not in the presence of PVAT vs vehicle (Dooku 2.9±1.9 vs Vehicle 7.3±5.2% PE contraction). Thus, Piezo1 is present and functional in the isolated aorta, important knowledge given that this molecule may serve as a translator of vascular pressure.