TRPV4 and chloride channels mediate volume sensing in trabecular meshwork cells.

Aqueous humor drainage from the anterior eye determines intraocular pressure (IOP) under homeostatic and pathological conditions. Swelling of the trabecular meshwork (TM) alters its flow resistance but the mechanisms that sense and transduce osmotic gradients remain poorly understood. We investigated TM osmotransduction and its role in calcium and chloride homeostasis using molecular analyses, optical imaging and electrophysiology. Anisosmotic conditions elicited proportional changes in TM cell volume, with swelling, but not shrinking, evoking elevations in intracellular calcium concentration [Ca