Pharmacological characterization of the mechanisms underlying the vascular effects of succinate

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• 作者：Letí ; cia N. Leite^a ; ^b ; ¹ ; Natá ; lia A. Gonzaga^a ; ^b ; ¹ ; Janaina A. Simplicio^a ; ^b ; Gabriel T. do Vale^a ; ^b ; José ; M. Carballido^c ; José ; C. Alves-Filho^a ; Carlos R. Tirapelli^b ; ^{crtirapelli@eerp.usp.br" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Succinate ; GPR91 ; Relaxation ; Aorta ; Endothelium ; Prostanoids ; Nitric oxide
• 刊名：European Journal of Pharmacology
• 出版年：2016
• 出版时间：15 October 2016
• 年：2016
• 卷：789
• 期：Complete
• 页码：334-343
• 全文大小：1752 K

文摘

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 F_1α (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. Similarly, succinate relaxed endothelium-intact and endothelium-denuded aortas isolated from both C57BL/6 and GPR91^−/– mice. 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, wortmannin 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 F_1α as well as eNOS phosphorylation at ser¹¹⁷⁷ residue. CaCl₂-induced contraction of endothelium-intact or endothelium-denuded aortas was not affected by succinate. The major 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 the NO-cGMP pathway, a vasodilator cyclooxygenase (COX) product(s) and the opening of K⁺ channels.