Routed protein migration after protein extravasation and water leakage caused by cold injury

The movement of extravasated endogenous protein induced by cold injury was investigated in the rat. Extravasated proteins were observed around the cold injury immediately after injury; within 3 hr they had moved into the ipsi- and contralateral hemispheres along the nerve fibres (routed protein migration). The water content in the areas where the extravasated protein was observed was increased, and NMR-CT scans (TR 2000 msec, TE 90 msec) showed high intensity patterns whose distribution and progression coincided with those of extravasated protein. NMR relaxation time, T1, showed a slight increase in the area where the extravasated protein was observed, but T2 value did not show any significant changes. In the opposite hemisphere, CBF decreased within 3 to 6 hours after injury. Local cerebral glucose utilization was reduced, but this change occurred more than 6 hours after injury. These results indicate that water leakage and protein extravasation occur simultaneously after the injury without any significant change of water state or protein conformation. Subsequently, a reduction of CBF is induced, which is followed by changes in cerebral metabolism.