Abstract 14157: Effects of Follistatin on the Regulation of Vascular Function by Perivascular Adipose Tissue in a Model of Essential Hypertension

Introduction: We previously showed that follistatin (FST), a potent activin inhibitor, lowers BP in the spontaneously hypertensive rat (SHR), a model of essential HTN. This was associated with improved vessel structure (reduced collagen) and function (reduced hypercontractility and improved endothelium-dependent relaxation). FST also reduced vascular oxidative stress (ROS). Perivascular adipose tissue (PVAT) is known to regulate vascular tone. FST induces browning and thus increased thermogenic activity of peripheral adipose tissue. Transition from white to brown adipose tissue is associated with decreased risk of CVD. Here, we assess FST effects on PVAT and its regulation of SHR vascular function. Methods: SHR were treated with FST from 12-20 weeks of age. Normotensive WKY rats served as controls. Mesenteric resistance arteries were isolated with or without intact PVAT. Vessel function was assessed using wire myography. In separate studies, white mesenteric and brown aortic PVAT, or peripheral fat depots, were isolated from WKY rats. These were introduced to WKY mesenteric vessels to study PVAT-isolated function. Results: Intact PVAT augmented constriction to KCl in SHR, but not WKY arteries, an effect prevented by FST. Improvement in endothelium-dependent vasodilation in FST-treated SHR was PVAT-dependent. SHR PVAT had increased adipocyte size and ROS (by DHE), both reversed by FST. Isolated PVAT from WKY incubated with pyocyanin (30’) to induce ROS augmented the KCl response, suggesting that FST inhibition of PVAT oxidative stress in HTN restores beneficial vascular effects. Incubation of WKY vessels with brown PVAT inhibited constriction to KCl more effectively than did white PVAT. Interestingly, peripheral white adipose (inguinal) did not have any anticontractile effect. Brown adipose (interscapular) effects were intermediate. Conclusions: Improvement in anticontractile effects of PVAT by FST in resistance vessels is associated with reduced PVAT oxidative stress. Brown PVAT is more effective than white PVAT in inhibiting vessel contraction, and unlike white PVAT, peripheral white adipose does not have anticontractile effects. Future work will assess effects of FST on PVAT browning, and whether browning itself can improve BP.