To investigate the effects of Rho kinase (ROCK) inhibitor on the production of nitric oxide (NO) and expression of endothelial nitric oxide synthase (eNOS) in cultured human trabecular meshwork cells (HTMC).

Primarily cultured HTMC were exposed to 0 µM, 10 µM or 100 µM Y-27632 for 3 days and NO production was assessed using Griess assay. After 24 hours, the effect of Y-27632 on the contraction of collagen matrix and the permeability of the HTMC monolayer was determined. The expression of eNOS mRNA was assessed using reverse transcription-polymerase chain reaction (RT-PCR) and cellular survival with the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay.

In HTMC, 10 µM and 100 µM Y-27632 significantly increased NO production after 1 day and 3 days ( p = 0.020 and 0.001, respectively). At 1 day after exposure, Y-276320 significantly relaxed the collagen matrix and increased the permeability of the HTMC monolayer (all p = 0.001) and the eNOS mRNA expression ( p = 0.039).

Increased NO production may play a role in the mechanism of increased trabecular outflow associated with ROCK inhibitor.