Increase in crosslinking of nonenzymatically glycosylated collagen induced by products of lipid peroxidation.

The increase in crosslinking in normal and nonenzymatically glycosylated rat tail tendon collagen after treatment with decomposing lipid hydroperoxides was assessed by measuring the breaking time of tendons immersed in 7 M urea under a 3 g weight at 40 degrees C (thermal rupture time). The incubation of tendons in 200 mM glucose for 43 h at 40 degrees C increased thermal rupture times from 5.15 to 26.38 min, (P less than 0.001) with no significant corresponding increase in tendons incubated in buffer alone. After incubation of the glycosylated tendons in the presence of peroxidized linoleic/arachidonic acid vesicles for about 20 h, their thermal rupture time increased to 3360 min (P less than 0.001). The rupture time for normal tendons after the same treatment was 206 min. These apparent crosslinking increases cannot be fully accounted for by reactions involving malondialdehyde, as incubation of both glycosylated and normal tendons in enzymatically produced malondialdehyde resulted in a modest two- to threefold increase in thermal rupture time.