Vanden Daele Laura, Boydens Charlotte, Pauwels Bart, Van de Voorde Johan
Department of Pharmacology, Ghent University, Ghent, Belgium.
Invest Ophthalmol Vis Sci. 2017 Mar 1;58(3):1702-1708. doi: 10.1167/iovs.16-20904.
The retinal circulation is regulated by different local factors and might include the retinal relaxing factor (RRF). This factor is found to be continuously released by the retina and relaxes smooth muscle cells. This review describes the current knowledge about the RRF. Despite many research efforts, the cellular source, identity, mechanism, and physiological role of the RRF remain largely unknown. Thus far, it seems that the RRF is a hydrophilic, thermostable, diffusible chemical messenger, which characteristics do not correspond with most well-known endogenous vasorelaxants. The RRF-induced relaxation seems to rely on activation of the inward rectifier K+ channels and the Rho kinase Ca2+ sensitization mechanism. Voltage-dependent K+ channels and plasma membrane Ca2+-ATPase might also be involved, whereas the involvement of cyclooxygenase is still a point of discussion. Furthermore, it appears that the RRF is involved in other relaxation pathways, namely those of hypoxia, adenosine, and adenosine triphosphate, hydrogen sulfide, γ-aminobutyric acid, and dorzolamide.
视网膜循环受多种局部因素调节，可能包括视网膜舒张因子（RRF）。现已发现该因子由视网膜持续释放，并可使平滑肌细胞舒张。本文综述了目前关于RRF的研究进展。尽管进行了大量研究，但RRF的细胞来源、特性、作用机制及生理功能仍不清楚。目前看来，RRF是一种亲水性、热稳定、可扩散的化学信使，其特性与大多数已知的内源性血管舒张剂不同。RRF诱导的舒张似乎依赖于内向整流钾通道的激活和Rho激酶钙敏化机制。电压依赖性钾通道和质膜钙ATP酶可能也参与其中，而环氧化酶的作用仍存在争议。此外，RRF似乎还参与其他舒张途径，即缺氧、腺苷、三磷酸腺苷、硫化氢、γ-氨基丁酸和多佐胺所介导的途径。
