IMMUNOLOCALIZATION OF ENDOTHELIN IN THE TRAUMATIZED SPINAL-CORD - RELATIONSHIP TO BLOOD-SPINAL CORD BARRIER BREAKDOWN

The purpose of this study was to determine the relationship between en dothelin-1 (ET-1), a prominent vasoactive agent, and the breakdown of the blood-spinal cord barrier along the axis of the cord after a moder ate spinal cord injury, In the first study rats (n = 10) were euthaniz ed 24 h after spinal cord injury and compared to sham (n = 5) and unop erated (n = 10) controls, Endothelin and immunoglobulins (IgG) were im mnunolocalized in adjacent sections of spinal cord using semiquantitat ive immunocytochemical techniques, In the second study animals were pr etreated with the endothelin antagonist Bosentan (n = 6) or vehicle (n = 6) prior to spinal cord injury, Animals were euthanized at 24 h pos tinjury, Ten minutes prior to euthanasia animals were given horseradis h peroxidase (HRP) intravenously. After perfusion fixation sections of cord were prepared for quantitative HRP histochemistry, After spinal cord injury there was enhanced staining for endothelin along the axis of the cord that correlated with the anatomical pattern of barrier bre akdown to IgG, In those animals that were pretreated with Bosentan, th ere was a significant reduction in barrier breakdown along the axis of the injured cord as compared to those animals that received vehicle o nly, Taken together, this data implicate involvement of endothelin in the axial pattern of barrier breakdown after spinal cord injury.