Hort Mariana Appel, Brighente Inês Maria Costa, Pizzolatti Moacir Geraldo, Ribeiro-do-Valle Rosa Maria
Instituto de Ciências Biológicas, Universidade Federal Do Rio Grande, Rio Grande, RS, Brazil.
Departamento de Farmacologia, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil.
J Tradit Complement Med. 2019 Apr 4;10(4):360-365. doi: 10.1016/j.jtcme.2019.04.001. eCollection 2020 Jul.
The species Mart. is a tree fern, commonly known as "xaxim", which is found in tropical and subtropical areas of Brazil. The present study investigated the mechanisms related with the vasorelaxant effects of an Ethyl Acetate Fraction (EAF) obtained from in rats' thoracic aorta rings. In pre-contracted vessels, EAF (0.1-1000 μg/mL) caused a concentration-dependent relaxation. The endothelium denudation, the nitric oxide (NO) synthase and guanylyl cyclase inhibitor reduced the vasodilation, indicating the participation of NO/cGMP pathway in its effect. The relaxation of EAF was abolished in the absence of extracellular Ca and was significantly decreased in the presence of Ca entry blocker, suggesting that Ca influx plays an important role in EAF effect and probably in eNOS activity. However, the PI3K/Akt pathway is not responsible for eNOS phosphorylation/activation. The vasodilator effect of EAF was partially inhibited by KCl 40 mM and almost totally abolished with L-NOARG + KCl 40 mM, indicating also the role of hyperpolarization in its effect. Calcium activated K channels are not involved in the EAF-induced hyperpolarization. The COX inhibitor, indomethacin, slightly reduced the vasodilation induced by EAF. In addition, EAF did not alter the relaxant effects of NO-donor, indicating that the relaxant activity cannot be attributed to free radical-scavenging properties. In conclusion, the present study showed that the EAF, causes an endothelium-dependent vasorelaxant effect in aorta that mainly involves the NO-cGMP pathway, hyperpolarization and prostanoids. The vasorelaxant activity of EAF can be attributed to the occurrence of polyphenol compounds.
Mart.属是一种树蕨，通常被称为“xaxim”，生长于巴西的热带和亚热带地区。本研究调查了从大鼠胸主动脉环中提取的乙酸乙酯馏分（EAF）产生血管舒张作用的相关机制。在预收缩的血管中，EAF（0.1 - 1000μg/mL）引起浓度依赖性舒张。内皮剥脱、一氧化氮（NO）合酶和鸟苷酸环化酶抑制剂可降低血管舒张，表明NO/cGMP途径参与了其作用。在无细胞外钙的情况下，EAF的舒张作用消失，而在存在钙内流阻滞剂时显著降低，这表明钙内流在EAF的作用中起重要作用，可能也参与了内皮型一氧化氮合酶（eNOS）的活性调节。然而，磷脂酰肌醇-3激酶/蛋白激酶B（PI3K/Akt）途径并不负责eNOS的磷酸化/激活。EAF的血管舒张作用被40 mM氯化钾部分抑制，而被L-精氨酸甲酯（L-NOARG）+ 40 mM氯化钾几乎完全消除，这也表明超极化在其作用中的作用。钙激活钾通道不参与EAF诱导的超极化。环氧化酶（COX）抑制剂吲哚美辛略微降低了EAF诱导的血管舒张。此外，EAF并未改变NO供体的舒张作用，表明其舒张活性不能归因于自由基清除特性。总之，本研究表明，EAF在主动脉中引起内皮依赖性血管舒张作用，主要涉及NO-cGMP途径、超极化和前列腺素。EAF的血管舒张活性可归因于多酚类化合物的存在。
