Ionic currents of human trabecular meshwork cells from control and glaucoma subjects.

Increasing evidence suggests that trabecular meshwork (TM) cells participate in the regulation of intraocular pressure by controlling the rate of filtration of the aqueous humor. Ionic conductances that regulate cell volume and shape have been suggested to play an important role in TM cell volume regulation. Here, we compared ionic currents from TM cells derived from a normal subject (CTM) and from an individual affected by glaucoma (GTM). We found that while the ionic current types were similar, the current amplitudes and percentage of cells endowed with specific current at baseline were different in the two cell lines. Thus, we found that the majority of CTM cells were endowed with a swelling-activated Cl(-) current at baseline, whereas in the majority of GTM cells this current was not active at baseline and became activated only after perfusion with a hypotonic solution. An inward rectifier K(+) current was also more prevalent in CTM than in GTM cells. Our work suggests that disregulation of one or more of these ionic currents may be at the basis of TM cell participation in the development of glaucoma.