Leite, Leticia N, Gonzaga, Natalia A, Simplicio, Janaina A, do Vale, Gabriel T, Carballido, Jose, Alves_Filho, José C and Tirapelli, Carlos R (2016) Pharmacological characterization of the mechanisms underlying the vascular effects of succinate. European Journal of Pharmacology, 789 (Jul 27). pp. 334-343. ISSN 00142999

Abstract

We investigated the mechanisms underlying the vascular effects of succinate. Vascular reactivity experiments were performed in aortic rings isolated from male Wistar rats and C57BL/6 wild type (WT) or GPR91-/- mice. Nitrate/nitrite (NOx) was measured colorimetrically whereas 6-keto-prostaglandin F1α (stable product of prostacyclin) was measured by enzyme immunoassay (EIA). Phosphorylation of endothelial nitric oxide synthase (eNOS) was assessed by western immunoblotting. Functional assays revealed that the direct effect of succinate in the vasculature is biphasic. At lower concentrations succinate induced relaxation while at higher concentrations succinate induced vascular contraction. Succinate concentration-dependently relaxed rat aortic rings with intact endothelium. Endothelial removal reduced, but not abolished succinate-induced relaxation in Wistar rats and WT mice. In contrast, aortic rings from GPR91-/- mice only exhibited moderated responses, which were not modified by the absence of endothelium. Pre-incubation of endothelium-intact, but not endothelium-denuded rat aortic rings with L-NAME, indomethacin and tetraethylammonium (TEA) reduced succinate-induced relaxation. In endothelium-intact rings, succinate-induced relaxation was attenuated by ODQ, haemoglobin, Rp-8-Br-Pet-cGMPS, thapsigargin and SC-560. Blockade of K+ channels with 4-aminopyridine, apamin and charybdotoxin, reduced succinate-induced relaxation. Succinate increased the concentration of NOx and 6-keto-prostaglandin F1α in endothelium-intact aortas. Succinate increased eNOS phosphorylation at ser1177 residue. CaCl2-induced contraction of endothelium-intact or endothelium-denuded aortas was not affected by succinate. The major new finding of our study is that it first demonstrates a direct effect of succinate in the vasculature. Succinate displays a biphasic and concentration-dependent effect. The vascular relaxation induced by succinate is partially mediated by endothelial GPR91 receptors via NO-cGMP pathway, a vasodilator cyclooxygenase (COX) product(s) and the opening of K+ channels.

Item Type:	Article
Keywords:	GPR91,
Date Deposited:	12 Aug 2016 00:45
Last Modified:	12 Aug 2016 00:45
URI:	https://oak.novartis.com/id/eprint/29576