Spectrophotometric quantitation of rhodopsin in the human retina

The rhodopsin content of the human retina was determined spectrophotometrically. Retinas were removed completely by using an in vitro technique based on a simulation of retinal detachment. This method provides a total recovery of rod outer segments which contain the rhodopsin visual pigment or its apoprotein, opsin. Using this improved dissection method followed by a crude preparation of the retina, an opsin-rhodopsin content of 6.20 ± 0.64 nmol/retina (n = 9) was found. This is larger than values previously reported. Regeneration with a threefold excess of 11-cis-retinal improved the recovery of rhodopsin dramatically because the corneas of these human donor eyes were removed for corneal transplant surgery under relatively bright light that bleaches the retina nearly completely. The amount of rhodopsin that can be isolated will be sufficient for studies on early events in visual transduction using laser photolysis.