Absence of binding and impermeability to ferritins of gill endothelium in marine teleosts.

The surface binding characteristics and permeability properties of the endothelium of secondary lamellae from the gills of several species of marine teleosts were investigated by introducing cationized ferritin and native ferritin into the microcirculation under normal environmental conditions. Neither type of ferritin bound to the luminal surface of the gill endothelium. No transcellular movement of cationized ferritin was detected, either via transendothelial channels or individual vesicles, nor was passage of cationized ferritin through the tight intercellular junctions of the endothelium observed. Anionic binding sites in the endothelial basement membranes could not be identified. Binding and transport of ferritin were unaffected by normal changes in environmental temperatures over the range of -2 to + 15°C. These findings suggest that the endothelial cell surface of the gills from these fishes is a primary barrier to the extracapillary movement of blood borne constituents.