Cyclic GMP phosphodiesterase activator: Involvement in a hereditary retinal degeneration.

Cyclic GMP and its enzyme of metabolism, Phosphodiesterase, (PDE) appear to be involved in the normal processes of vision. An abnormality in the development of cyclic GMP PDE in the retina of the newborn Irish Setter dog also appears to be involved in at least one form of inherited retinal degeneration. Specifically, the enzyme in affected retinas fails to switch from a Calmodulin-Dependent to a Calmodulin-Independent form. This failure, along with low levels of Calmodulin could account for the high cyclic GMP content and photoreceptor loss characteristic of early-onset retinal degeneration.