Protein kinases in the subretinal fluid

Subretinal fluid in primary rhegmatogenous retinal detachment: physiopathology and composition

During retinal detachment, subretinal fluid is present, whose composition and physiopathology are still little known. Under normal conditions, osmotic and oncotic pressures help keep the retina in place, but the main retinal attachment force is provided by active transport in the pigment epithelium. Subretinal fluid composition varies according to detachment duration; total protein concentration in subretinal fluid increases with time. In addition, all proteins are qualitatively modified. The detached retina loses its oxygen supply, and it then uses the anaerobic pathway to degrade glucose. Thus, long-duration retinal detachments feature increased lactic acid and dextrose concentrations. Phospholipids are also increased in subretinal fluid, reflecting retinal degradation. This review presents data on the physiopathology and composition of the subretinal fluid in retinal detachments.

The lipoprotein profile and phospholipase activity of subretinal fluid

We have studied the lipoprotein profile of subretinal fluid by crossed immunoelectrophoresis using an antiserum against apolipoprotein A-I. If the detachment had occurred recently, we found that the subretinal fluid contained only the alpha 1-lipoprotein of serum. However, if the detachment was of longer duration an increasing amount of an electrophoretically slower-moving lipoprotein was also present in the subretinal fluid. We present evidence that subretinal fluid contains an enzyme, phospholipase A, which can form the slower-moving component from alpha 1-lipoprotein. Since the retina has a high phospholipid content, permanent damage may be caused to its structure by the action of this hydrolysing enzyme.