Investigations on contractile properties of retinal pigment epithelial cells.

We have investigated the contractile properties of human and bovine retinal pigment epithelial (RPE) cells in culture. In collagen gels, RPE cells sent out processes which were able to retract the gels. In a glycerinated model of contraction, RPE cells contracted and aggregated into clusters in response to the addition of ATP to the media. This contraction was very likely mediated by contractile proteins which are arranged in circumferential microfilament bundles in RPE cells. SDS-PAGE analysis of the RPE cell cytoskeletal elements showed protein bands of 200 kD and 43 kD, probably heavy-chain myosin and actin, respectively; in human RPE, cells bands of 58 kD and 52 kd, representing intermediate filament subunits, were evident; in bovine cells the 58-kD band was observed.