Journal of Neurophysiology, Vol 76, Issue 3 1572-1580, Copyright © 1996 by APS

ARTICLES

Compression injury of mammalian spinal cord in vitro and the dynamics of action potential conduction failure

R. Shi and A. R. Blight
Division of Neurosurgery, University of North Carolina at Chapel Hill 27599, USA.

1. White matter strips from the ventral spinal cord of adult guinea pigs were isolated in vitro, and their electrophysiological characteristics and response to controlled focal compression injury were examined. A double sucrose gap technique was used for stimulation and recording at opposite ends of a 12.5 mm-diam central well superfused with oxygenated Krebs solution. 2. The compound action potential recorded with the sucrose gap was similar in form to single fiber potentials recorded with intra-axonal electrodes, including the presence of a prolonged depolarizing afterpotential. 3. Three types of conduction block resulting from compression were identified: an immediate, spontaneously reversible component, which may result from a transient increase in membrane permeability and consequent disturbance of ionic distribution; a second component that was irreversible within 1-2 h of recording, perhaps resulting from complete axolemmal disruption; and a third component, which may have been due to disruption of the myelin sheath, that appeared to be reversible with application of 10-100 microM of the potassium channel blocker 4-aminopyridine. 4. Conduction deficits--decreased amplitude and increased latency of the compound potential--were stable between 5 and 60 min postinjury, and their intensity corellated with the extent of initial compression over a full range of severity. 5. Stimulus-response data indicate that mechanical damage to axons in compression was evenly distributed across the caliber spectrum, suggesting that the susceptibility of large caliber axons seen histopathologically after injury in vivo may be based on delayed, secondary processes. 6. The model provides the ability to monitor changes in the properties of central myelinated axons after compression injury in the absence of pathological variables related to vascular damage. This initial investigation found no evidence of secondary deterioration of axons in the 1st h after injury, although there was evidence of both transient and lasting mechanical damage to axons and their myelin sheaths.

This article has been cited by other articles:

				P. Liu-Snyder, M. P. Logan, R. Shi, D. T. Smith, and R. B. Borgens Neuroprotection from secondary injury by polyethylene glycol requires its internalization J. Exp. Biol., April 15, 2007; 210(8): 1455 - 1462. [Abstract] [Full Text] [PDF]

				R. Shi and J. Whitebone Conduction Deficits and Membrane Disruption of Spinal Cord Axons as a Function of Magnitude and Rate of Strain J Neurophysiol, June 1, 2006; 95(6): 3384 - 3390. [Abstract] [Full Text] [PDF]

				G. C. DeLuca, G. C. Ebers, and M. M. Esiri Axonal loss in multiple sclerosis: a pathological survey of the corticospinal and sensory tracts Brain, May 1, 2004; 127(5): 1009 - 1018. [Abstract] [Full Text] [PDF]

				J. M. Jensen and R. Shi Effects of 4-Aminopyridine on Stretched Mammalian Spinal Cord: The Role of Potassium Channels in Axonal Conduction J Neurophysiol, October 1, 2003; 90(4): 2334 - 2340. [Abstract] [Full Text] [PDF]

				M. A. Peasley and R. Shi Resistance of isolated mammalian spinal cord white matter to oxygen-glucose deprivation Am J Physiol Cell Physiol, September 1, 2002; 283(3): C980 - C989. [Abstract] [Full Text] [PDF]

				S. Love and H. B. Coakham Trigeminal neuralgia: Pathology and pathogenesis Brain, December 1, 2001; 124(12): 2347 - 2360. [Abstract] [Full Text] [PDF]

				R. Shi, T. Asano, N. C. Vining, and A. R. Blight Control of Membrane Sealing in Injured Mammalian Spinal Cord Axons J Neurophysiol, October 1, 2000; 84(4): 1763 - 1769. [Abstract] [Full Text] [PDF]

				R. M. LoPachin, C. L. Gaughan, E. J. Lehning, Y. Kaneko, T. M. Kelly, and A. Blight Experimental Spinal Cord Injury: Spatiotemporal Characterization of Elemental Concentrations and Water Contents in Axons and Neuroglia J Neurophysiol, November 1, 1999; 82(5): 2143 - 2153. [Abstract] [Full Text] [PDF]

				R. Shi and R. B. Borgens Acute Repair of Crushed Guinea Pig Spinal Cord by Polyethylene Glycol J Neurophysiol, May 1, 1999; 81(5): 2406 - 2414. [Abstract] [Full Text] [PDF]

				A. B. Lore, J. A. Hubbell, D. S. Bobb Jr, M. L. Ballinger, K. L. Loftin, J. W. Smith, M. E. Smyers, H. D. Garcia, and G. D. Bittner Rapid Induction of Functional and Morphological Continuity between Severed Ends of Mammalian or Earthworm Myelinated Axons J. Neurosci., April 1, 1999; 19(7): 2442 - 2454. [Abstract] [Full Text] [PDF]