Abstract
Hydrogen sulfide (H2S) and nitric oxide (NO) are gaseous mediators that are endogenously produced in mammalian ocular tissues. We tested the hypothesis that NO can regulate the basal production of H2S in isolated bovine neural retina. Methods: H2S and NO concentrations in bovine retina was measured using well‐established colorimetric assays. Retina homogenates were incubated at 37°C for different time periods for determination of basal endogenous production of H2S and NO. In studies examining the effects of the NO donor (SNP) and NO synthase inhibitor (L‐NAME) on basal levels of H2S production, retina tissues were homogenized in the presence of the respective compounds before assays were performed. Results: L‐NAME (300 nM ‐ 500 µM) caused a concentration‐dependent decrease (p < 0.05) in the basal endogenous production of H2S reaching a maximum at 500 µM. On the other hand, SNP (10 ‐ 100 µM) enhanced significantly (p < 0.05) the endogenous H2S production. In the concentration range, 10 µM to 300 µM, L‐cysteine attenuated basal endogenous production of NO reaching a maximum at 300 µM. Conclusions: We conclude that NO can interact with the pathway/s involved in the production of H2S in the retina. Furthermore, endogenously produced H2S can regulate basal NO concentrations. Further studies are needed to understand the pharmacological/physiological basis of the interaction between these two gases in the retina.