Vanden Daele Laura, Boydens Charlotte, Van de Voorde Johan
Department of Pharmacology - Vascular Research Unit, Ghent University, Corneel Heymanslaan 10, 9000, Ghent, Belgium.
Graefes Arch Clin Exp Ophthalmol. 2018 Oct;256(10):1905-1912. doi: 10.1007/s00417-018-4096-4. Epub 2018 Aug 13.
The retinal relaxing factor (RRF) is a continuously released factor from the retina that causes vasorelaxation, the identity and potential role in physiology of which remain largely unknown. Experiments were performed to find out whether the RRF-induced relaxation is influenced by serotonin, glutamate, L-cysteine, the cytochrome P450 pathway, the cyclooxygenase pathway, or oxidative stress. In addition, the sensitivity of retinal and non-retinal arteries towards the RRF was compared.
In vitro tension measurements were performed on isolated mouse femoral or bovine retinal arteries to study the vasorelaxing effect of the RRF, induced by mouse or bovine retinas.
The presence of serotonin, glutamate, or L-cysteine did not alter the RRF-induced relaxation. Increasing oxidative stress by hydroquinone and diethyldithiocarbamic acid sodium salt enhanced the RRF response. Inhibition of the cytochrome P450 or the cyclooxygenase pathway did not cause any alteration. Surprisingly, the RRF-induced relaxation was enhanced by the presence of flufenamic acid or carbenoxolone. Furthermore, bringing retinal tissue in close contact with retinal or non-retinal arteries induced comparable relaxations.
Serotonin, glutamate, L-cysteine, the cytochrome P450, and the cyclooxygenase pathway do not influence the RRF-induced relaxation and the RRF-induced relaxation seems to be resistant to oxidative stress. The mechanism responsible for the enhanced RRF-induced relaxation in the presence of flufenamic acid or carbenoxolone remains elusive and the RRF does not show more effectivity on retinal arteries.
视网膜舒张因子（RRF）是一种从视网膜持续释放的因子，可引起血管舒张，其身份和在生理学中的潜在作用在很大程度上仍不清楚。进行实验以探究RRF诱导的舒张是否受血清素、谷氨酸、L-半胱氨酸、细胞色素P450途径、环氧化酶途径或氧化应激的影响。此外，比较了视网膜动脉和非视网膜动脉对RRF的敏感性。
对分离的小鼠股动脉或牛视网膜动脉进行体外张力测量，以研究由小鼠或牛视网膜诱导的RRF的血管舒张作用。
血清素、谷氨酸或L-半胱氨酸的存在并未改变RRF诱导的舒张。对苯二酚和二乙基二硫代氨基甲酸钠增加氧化应激可增强RRF反应。细胞色素P450或环氧化酶途径的抑制未引起任何改变。令人惊讶的是，氟芬那酸或甘珀酸的存在增强了RRF诱导的舒张。此外，使视网膜组织与视网膜或非视网膜动脉紧密接触可诱导相当的舒张。
血清素、谷氨酸、L-半胱氨酸、细胞色素P450和环氧化酶途径不影响RRF诱导的舒张，且RRF诱导的舒张似乎对氧化应激具有抗性。在氟芬那酸或甘珀酸存在下RRF诱导的舒张增强的机制仍然难以捉摸，并且RRF对视网膜动脉未显示出更大的效力。
