Spinal cord energy metabolism following compression trauma to the feline spinal cord

Abstract

The purpose of this study was to determine the spinal cord metabolic state for 24 hours after compression trauma to the feline spinal cord. Cats were anesthetized with pentobarbital and injured by placing a 190-gm weight on the spinal cord for 5 minutes. Biochemical analysis of the injured segment revealed a significant depletion in the levels of adenosine triphosphate (ATP), phosphocreatine (P-creatine), and total adenylates for the entire 24-hour recovery period. Glucose levels initially declined, but by 1 hour had normalized, and at 8 and 24 hours were significantly supranormal. The lactate/pyruvate ratio and tissue lactate concentrations increased four and five and half times, respectively, for the first 4 hours after injury. Between 8 and 24 hours, lactate levels remained elevated, whereas the lactate/pyruvate ratio declined to contol levels as the result of a significant rise in the tissue pyruvate concentration. This sequence of metabolic changes suggested that metabolism was probably not homogeneous throughout the injured segment, and that tissue metabolic rate was depressed for the initial 4 hours after trauma then increased in metabolically active tissue for the remainder of the 24-hour recovery period. This model of spinal cord trauma results in a severe, prolonged ischemia and metabolic injury to the affected tissue. Whether these metabolic changes results from or cause the tissue damage and irreversible paraplegia associated with this type of spinal cord injury remains to be determined.