I have looked into altitude and NOS activity a lot because of the issues I have at altitude as well. This is largely controlled by the genetics of NOS2. https:

I have looked into altitude and NOS activity a lot because of the issues I have at altitude as well. This is largely controlled by the genetics of NOS2. https://www.sciencedirect.com/science/article/pii/S0002929717303920 https://www.sciencedirect.com/science/article/pii/S000292971... And there is a clear link to low NO and CF https://www.cysticfibrosisjournal.com/article/S1569-1993(05)00057-3/fulltext https://www.cysticfibrosisjournal.com/article/S1569-1993(05)... It seems the issue with CF is NOS1. (I have an issue with NOS2) https://www.atsjournals.org/doi/full/10.1164/ajrccm.162.6.2003106 https://www.atsjournals.org/doi/full/10.1164/ajrccm.162.6.20... Look at the cofactors that help NOS1 function and that might give you some clues at what may help: https://www.uniprot.org/uniprot/P29475 https://www.uniprot.org/uniprot/P29475 Glutathione will help protect against both BH4 depletion as well as forming peryoxinitires. You intuitions are excellent.