Opsin phosphorylation in retinas from autopsy eyes with retinitis pigmentosa

Opsin phosphorylation in light was detected in three retinas from autopsy eyes with retinitis pigmentosa (RP) including one with sex-linked RP and two with autosomal recessive RP, that were studied at postmortem intervals of 1-4 hr. In these retinas from RP eyes, opsin phosphorylation in light was reduced compared with that in normal human retinas, a finding that is compatible with reduced amounts of opsin due to extensive loss of photoreceptor cells. ATP and GTP levels, although reduced below normal, also were easily detectable, supporting the idea that the reduction in opsin phosphorylation was due to loss of photoreceptor cells and not to a reduced capacity for energy metabolism. These findings in these RP retinas contrast with those in rd mice and Irish setters with rod-cone dysplasia in which a failure of opsin phosphorylation has been detected prior to onset of photoreceptor cell degeneration.