Background: To determine whether nitric oxide synthase (NOS) protein expression can be modulated by forskolin in porcine ciliary processes.
Method: Western blot analysis using mouse monoclonal antibodies against NOS I (neuronal NOS or nNOS), NOS II (macrophage NOS or macNOS), and NOS III (endothelial NOS or eNOS) was performed in porcine ciliary processes. Expression of NOS I and II was also assessed in the presence or in the absence of 1 microM forskolin exposure (4 and 24 hours).
Results: All three NOS isoforms could be detected in isolated porcine ciliary processes. Protein expression for NOS I was about 6 times higher than for NOS III and 15 times higher than for NOS II. In comparison to controls, after forskolin exposure, NOS I protein expression was increased by about 1.5-fold. No change could be observed in NOS II protein expression after forskolin exposure.
Conclusions: Nitric oxide is involved in transepithelial fluid transport of different organs (lung, kidney, colon, etc.) and is suspected to play a role in ciliary processes by modulating the aqueous humor production. The present study indicates that forskolin (which increases cAMP production) modulates NOS I protein expression in isolated porcine ciliary processes. These results suggest that selective inhibition of NOS I could be tried for reducing aqueous humor production. The clinical relevance requires further investigations.