Abstract
Purpose: :
To evaluate the effect of nitric oxide synthase inhibitor, N(G)–nitro–L–arginine methyl ester(L–NAME) on the hypoxia–induced vascular endothelial growth factor(VEGF) expression in the human retinal pigment epithelial cells.
Methods: :
The cultured human retinal pigment epithelial cells were incubated in the culture media containing 0.5, 1, 5 or 20µM L–NAME. Those cells were incubated under an anaerobic condition (37oC, 85%N2, 10%O2, 5%CO2) for 6, 12, 24, 48, or 72 hours respectively. As a control group, the cells were incubated under anaerobic condition and without the L–NAME addition. At each time point the hypoxia–induced VEGF expression of the retinal pigment epithelial cells was assayed by northern blot analysis.
Results: :
As a result the control group indicated an increased L–NAME expression up to 24 hours incubation, but no further increase thereafter. However, the L–NAME treated groups showed decreased VEGF expression dependent on the dose. In the 0.5µM L–NAME treated group, there was no significant difference between two groups at 6 hours incubation. But at 12 hours of incubation, the treated group showed decreased VEGF expression compared to control group. At 24 hours or more incubation, no significant difference was found between the two groups. In the 1.0µM L–NAME treated group, VEGF expressions decreased slightly compare to control group at 6 hours and 12 hours of incubations. But at 24 hours or more incubation, there was no significant difference between two groups. In the 5.0µM L–NAME treated group, VEGF expressions decreased significantly compare to the control group at 6 hours and 12 hours incubations. But at 24 hours or more incubation, there was no significant difference between two groups. In the 20µM L–NAME treated group, VEGF expression decreased significantly throughout the incubation period compared to the control group. The difference was most remarkable at 6 hours of incubation. With time, the concentration difference was a little bit decreased, but still significant throughout the incubation period.
Conclusions: :
L–NAME inhibited the hypoxia–induced VEGF expression in the cultured human retinal epithelial cells. The inhibitory effect was dose–dependent.
Keywords: drug toxicity/drug effects • retinal pigment epithelium • hypoxia