Figure 2. Cyclic guanosine monophosphate (cGMP) levels in primary human trabecular meshwork (hTM) cells. A:SA-2 (100, 200, 1,000 µM) increased the cyclic guanosine monophosphate (cGMP) level in primary human trabecular meshwork (hTM) cells. hTM cells (hTM-80, hTM-34) were treated with SA-2 (100 µM, 200 µM, and 1,000 µM) or vehicle for 30 min. cGMP was assayed using the cell lysate using the enzyme immunoassay kit from Cayman Chemicals (Ann Arbor, MI) following the manufacturer’s instructions. The EC₅₀ was calculated to be 20.3 µM using GraphPad Prism 7.0. B: SA-2 NPs (0.1% equivalent to 250 µM of SA-2) increased cGMP in hTM cells. *p<0.05, ***p<0.001, unpaired t test. Experiments were performed in triplicate with n = 4 technical replicates. The results showed that SA-2 and SA-2 NPs were able to significantly increase cGMP levels in two different types of primary hTM cells. Values are expressed in mean ± standard error of the mean (SEM).