Norepinephrine levels in experimental spinal cord trauma. Part 1: Biochemical study of hemorrhagic necrosis.

Levels of norepinephrine (NE) in the spinal cord tissue of nontraumatized cats are highest in the cervical and lumbar enlargements. A rather uniform but slightly increasing concentration gradient from cephalad to caudad is observed in the thoracic segments. A 500 gm-cm trauma at the T-5 or C-7 spinal cord segment did not demonstrate any significant increase in NE levels measured sequentially over a 4-hour period after trauma. Dopamine levels could not be detected in the nontraumatized or traumatized cat spinal cords. Four traumatized cats treated with alpha methyl tyrosine, a tyrosine hydroxylase inhibitor, and followed clinically for 5 months showed no improvement in neurological function when compared to untreated traumatized cats. This study does not support the norepinephrine hypothesis of experimental spinal cord trauma.