CALCIUM-INDUCED DISRUPTION OF THE LENS CYTOSKELETON

Ionic homeostasis is essential to lens clarity and the lens epithelium plays a large part in homeostasis, through vectorial transport. In mo st epithelia maintenance of vectorial function depends on the cytoskel eton. Capsule/epithelium preparations from human donor lenses have bee n used for immunohistochemical investigations of both normal epithelia l cell cytoskeletal structure, and of structural changes induced by in creasing cell calcium. A sustained increase in intracellular calcium, induced by incubation with A23187 and W7, led to a loss of cytoskeleta l organisation. Changes included depolymerisation of cytoplasmic actin filaments, disaggregation of microtubules and initial thickening, fol lowed by breakdown, of vimentin intermediate filaments. In addition, s pectrin staining, normally confined to the basal-lateral plasma membra nes, became diffuse within the cytoplasm. Such disruptions of cytoskel etal structure would decrease ionic control, leading to increasing osm otic stress.