Genetic Deletion of the NOS3 Gene in CAV1-/- Mice Restores Aqueous Humor Outflow Function.

Purpose: The purpose of this study was to investigate the impact of genetic deletion of NOS3 in CAV1-/- mice on aqueous humor outflow function using a mouse genetic double knockout model (DKO, NOS3-/- CAV1-/-).

Methods: IOP was measured in DKO, NOS3 KO, CAV1 KO, and wild-type (WT) mice by rebound tonometry. Outflow facility was measured by perfusing enucleated mouse eyes at multiple pressure steps. Sodium nitroprusside (SNP) and L-NG-nitroarginine methyl ester (L-NAME) was administered topically, whereas the contralateral eyes served as vehicle controls. IOP was measured in both eyes before drug treatment and 1 hour after the last drug treatment. Mock aqueous humor ± the nitric oxide (NO) donor SNP or NOS inhibitor L-NAME was perfused into enucleated eyes.

Results: IOP was 11 ± 0.23 mm Hg in DKO mice, which was similar to WT mice and significantly lower than CAV1 KO mice (n = 18, P > 0.05). NOS3 deletion in CAV1-/- mice resulted in a 1.9-fold increase in conventional outflow facility (Ccon) compared with CAV1 KO mice (n = 7, P < 0.05). Topical application of NO donor SNP did not significantly change IOP (n = 18, P > 0.05) or Ccon in DKO mice (SNP, n = 20; vehicle, n = 11, P > 0.05). Topical application of L-NAME significantly increased IOP in WT, DKO, and CAV1 mice by reducing Ccon. Nitrotyrosine and PKG levels of DKO mice were similar to, whereas sGC was lower than, WT mice (P < 0.05).

Conclusions: Genetic deletion of NOS3 in CAV1-deficient mice restored IOP and conventional aqueous humor drainage to WT level. NOS3 and CAV1 interaction is important to IOP regulation.