Objective: To study the role of perivascular adipose tissue (PVAT) in the reactivity of rat and human vessels.
Methods: Iliac and mesenteric arteries were obtained from normotensive Sprague-Dawley rats, hypertensive transgenic (mRen2)27 rats overexpressing mouse renin, and (mRen2)27 rats made diabetic with streptozotocin. Human coronary arteries were obtained from donors. Concentration-response curves were constructed to endothelin-1 and acetylcholine with and without PVAT. The contribution of NO and endothelium-dependent hyperpolarization (EDH) were determined making use of the NO synthase inhibitor L-NAME and the EDH inhibitors apamin + TRAM-34. The endothelin type A and type B (ETA, ETB) receptor blockers BQ123 and BQ788, the chemerin inhibitors α-NETA and pravastatin, and the angiotensin receptor blocker losartan were also used.
Results: In rat iliac arteries, PVAT diminished endothelin-induced constriction, while the opposite was true in human coronaries. Coronary effects were unaltered by α-NETA, pravastatin, or losartan. ETB receptor-mediated relaxation in iliac arteries occurred only with PVAT, and BQ123 blocked endothelin-1-induced constriction. Diabetes upregulated the anticontractile effects of PVAT. In rat mesenteric arteries, acetylcholine-induced relaxation with PVAT relied on NO, and on NO + EDH without PVAT. Diabetes upregulated the EDH component exclusively with PVAT.
Conclusion: PVAT modulates ET-1-induced constriction in a vessel type-dependent manner. Its enhancing effects in coronaries involved neither chemerin nor angiotensin II. Its anticontractile effects in rat iliac arteries involved ETB receptor-mediated relaxation. Diabetes upregulated PVAT's anticontractile effects. In mesenteric arteries, PVAT counterbalanced the EDH component of the relaxant effect of acetylcholine. Diabetes reversed this effect by upregulating the EDH component.
Keywords: Hypertension; angiotensin; chemerin; diabetes; endothelin-1; perivascular adipose tissue; vascular function.
What is the context?The role of perivascular adipose tissue (PVAT) in vascular reactivity in pathological conditions is poorly understood.What is the study about?This study investigates the role of PVAT in vascular reactivity in animal and human vessels.What are the results?PVAT has vasoconstrictor and vasorelaxant effects depending on location and tissue. In human coronary arteries, PVAT-mediated vasoconstrictor effects do not involve chemerin or angiotensin II. PVAT’s anticontractile effects in rat iliac arteries are mediated through a mechanism involving endothelin type B receptor-dependent relaxation. Moreover, diabetes but not hypertension dysregulates PVAT’s anticontractile effects in rat mesenteric vessels.