Department of Ophthalmology, Baylor College of Medicine, Houston, TX 77030, USA.
Cells. 2021 May 22;10(6):1288. doi: 10.3390/cells10061288.
(1) Background: High-tension glaucoma damages the peripheral vision dominated by rods. How mechanosensitive channels (MSCs) in the outer retina mediate pressure responses is unclear. (2) Methods: Immunocytochemistry, patch clamp, and channel fluorescence were used to study MSCs in salamander photoreceptors. (3) Results: Immunoreactivity of transient receptor potential channel vanilloid 4 (TRPV4) was revealed in the outer plexiform layer, K channel TRAAK in the photoreceptor outer segment (OS), and TRPV2 in some rod OS disks. Pressure on the rod inner segment evoked sustained currents of three components: (A) the inward current at <-50 mV (), sensitive to Co; (B) leak outward current at ≥-80 mV (), sensitive to intracellular Cs and ruthenium red; and (C) cation current reversed at ~10 mV (). Hypotonicity induced slow currents like . Environmental pressure and light increased the FM 1-43-identified open MSCs in the OS membrane, while pressure on the OS with internal Cs closed a Ca-dependent current reversed at ~0 mV. Rod photocurrents were thermosensitive and affected by MSC blockers. (4) Conclusions: Rods possess depolarizing (TRPV) and hyperpolarizing (K) MSCs, which mediate mutually compensating currents between -50 mV and 10 mV, serve as an electrical cushion to minimize the impact of ocular mechanical stress.
（1）背景：高压性青光眼会损害以视杆为主的周边视力。在外视网膜中机械敏感通道（MSCs）如何介导压力反应尚不清楚。（2）方法：免疫细胞化学、膜片钳和通道荧光用于研究蝾螈光感受器中的 MSCs。（3）结果：在外丛状层中发现瞬时受体电位通道香草素 4（TRPV4）的免疫反应性，在光感受器外节（OS）中有 K 通道 TRAAK，在一些视杆 OS 盘上有 TRPV2。对杆状内节施加压力会引起三种成分的持续电流：（A）<-50 mV 的内向电流（），对 Co 敏感；（B）≥-80 mV 的漏向外电流（），对内流 Cs 和钌红敏感；和（C）在10 mV 处反转的阳离子电流（）。低渗诱导类似于的缓慢电流。环境压力和光照增加了 OS 膜中 FM 1-43 鉴定的开放 MSCs，而用内部 Cs 对 OS 施加压力会关闭在0 mV 处反转的 Ca 依赖性电流。杆状光电流对热敏感，并受 MSC 阻滞剂的影响。（4）结论：视杆具有去极化（TRPV）和超极化（K）MSCs，它们在-50 mV 和 10 mV 之间介导相互补偿的电流，作为电缓冲垫，以最小化眼机械应激的影响。
