Effects of nitric oxide donors and nitric oxide synthase substrates on ciliary muscle contracted by carbachol and endothelin for possible use in myopia prevention

Research has suggested that the development of myopia may possibly be preve nted by the use of drugs which facilitate relaxation of the intraocular cil iary muscle. We examined the effects of five nitric oxide-producing agents - two nitric oxide donors, hydralazine and sodium nitrite, and three nitric oxide synthase substrates, L-arginine, L-canavanine, and N-benzoyl-L-argin ine ethyl ester - on isolated bovine ciliary muscle maximally contracted wi th either carbachol or endothelin-l, Of these agents, hydralazine and L-can avanine produced a relaxing effect on endothelin-1-contracted muscle that w as significantly greater than relaxing effect on carbachol-contracted muscl e. These results indicate that hydralazine and L-canavanine could possibly be used for the prevention of myopia by relaxing the ciliary muscle with fe w anticholinergic and cycloplegic side effects.