The Variety of Mechanosensitive Ion Channels in Retinal Neurons

Abstract

Alterations in intraocular and external pressure critically involve the pathogenesis of glaucoma, traumatic retinal injury (TRI), and other retinal disorders, and retinal neurons have been reported to express multiple mechanical-sensitive channels (MSCs) in recent decades. However, the role of MSCs in visual functions and pressure-related retinal conditions has been unclear. This review will focus on the variety and functional significance of the MSCs permeable to K+, Na+, and Ca2+, primarily including the big potassium channel (BK); the two-pore domain potassium channels TRAAK and TREK; Piezo; the epithelial sodium channel (ENaC); and the transient receptor potential channels vanilloid TRPV1, TRPV2, and TRPV4 in retinal photoreceptors, bipolar cells, horizontal cells, amacrine cells, and ganglion cells. Most MSCs do not directly mediate visual signals in vertebrate retinas. On the other hand, some studies have shown that MSCs can open in physiological conditions and regulate the activities of retinal neurons. While these data reasonably predict the crossing of visual and mechanical signals, how retinal light pathways deal with endogenous and exogenous mechanical stimulation is uncertain.