Alterations in spinal cord norepinephrine levels following experimentally produced trauma in normal and adrenalectomized cats

Spinal cords of normal and adrenalectomized cats were subjected to experimentally produced blunt trauma and then analyzed for changes in concentration of norepinephrine (NE). In normal cats the NE concentrations at the lesion site rose 63% over control after one hour, and by $\text{1}\text{1}\text{2}$ to 2 hours had returned to control level. Little change in concentration was observed in cord segments 2 cm from injury site, but segments adjacent to the injury exhibited increased levels of NE. NE concentrations one hour after trauma in adrenalectomized cats were lower than those measured in normal controls. It is postulated that the mechanism of NE accumulation involves a breakdown of the blood-spinal cord barrier thereby allowing peripherally produced NE to enter the cord parenchyma from the systemic circulation.