Exudation of fibronectin and albumin after spinal cord injury in rats.

Spinal cord of the rat was investigated immunohistochemically to detect signs of extravasation of fibronectin in animals in which the cord was subjected to different degrees of compression trauma. Immunohistochemistry was performed after survival periods of 4 and 24 h and parallel sections were incubated for albumin immunoreactivity to detect signs of breakdown of the blood-spinal cord barrier. Extravascular reaction products indicating the presence of fibronectin were found within and in the vicinity of the compression provided that bleeding had occurred in the spinal cord, i.e., in rats with severe trauma. Immunoreactive material indicating extravascular albumin was present in the traumatized region and in many segments of the cord located away from the compressed part. Such material was seen both proximal and distal to the primary injury and even in rats with a low magnitude of compression. Generally, with more severe trauma and longer survival periods extravascular albumin was more extensively distributed along the cord. No signs of fibronectin antigen were detected in spinal cord segments away from the compression even though such regions showed albumin immunoreactivity outside the vessels. The results indicate that within and close to the primary injury of compressed spinal cord exudation of fibronectin may occur from the plasma of microvessels provided that the impact is severe enough to cause intramedullary hemorrhages.