The Vasoactive Effect of Perivascular Adipose Tissue and Hydrogen Sulfide in Thoracic Aortas of Normotensive and Spontaneously Hypertensive Rats.

The objective of this study was to investigate the vasoregulatory role of perivascular adipose tissue (PVAT) and its mutual interaction with endogenous and exogenous H 2 S in the thoracic aorta (TA) of adult normotensive Wistar rats and spontaneously hypertensive rats (SHRs). In SHRs, hypertension was associated with cardiac hypertrophy and increased contractility. Regardless of the strain, PVAT revealed an anticontractile effect; however, PVAT worsened endothelial-dependent vasorelaxation. Since H 2 S produced by both the vascular wall and PVAT had a pro-contractile effect in SHRs, H 2 S decreased the sensitivity of adrenergic receptors to noradrenaline in Wistar rats. While H 2 S had no contribution to endothelium-dependent relaxation in Wistar rats, in SHRs, H 2 S produced by the vascular wall had a pro-relaxant effect. We observed a larger vasorelaxation induced by exogenous H 2 S donor in SHRs than in Wistar rats. Additionally, in the presence of PVAT, this effect was potentiated. We demonstrated that PVAT of the TA aggravated endothelial function in SHRs. However, H 2 S produced by the TA vascular wall had a pro-relaxation effect, and PVAT revealed anti-contractile activity mediated by the release of an unknown factor and potentiated the vasorelaxation induced by exogenous H 2 S. All these actions could represent a form of compensatory mechanism to balance impaired vascular tone regulation.