Ruthenium red staining of blood-bubble interface in acute decompression sickness in rat.

The ultrastructure of the blood-bubble interface has been studied in rats decompressed experimentally. Subsequent to staining with ruthenium red there was detected by electron microscopy a continuous envelope like layer about 20 nm thick at the bubble-facing surface of the interface. The envelope like structure was visualized also by concanavalin A-ferritin, a glycosyl- and mannosyl residue-recognizing lectin coupled with an electron-dense probe, but the structure was not at all seen by the use of the conventional stains used in electron microscopy, uranyl acetate and lead citrate. No electron-dense layer was discernible on the application of only osmium tetroxide without further staining. The results indicate that material stainable by ruthenium red, and binding concanavalin A (probably a glycoprotein), is concentrated at the blood-bubble interface upon decompression. It is suggested that it plays a role in stabilization of the bubble and in the hematological alterations that are frequently observable in decompression sickness.