Large naturally-produced electric currents and voltage traverse damaged mammalian spinal cord

Immediately after damage to the nervous system, a cascade of physical, physiological, and anatomical events lead to the collapse of neuronal function and often death. This progression of injury processes is called "secondary injury." In the spinal cord and brain, this loss in function and anatomy is largely irreversible, except at the earliest stages. We investigated the most ignored and earliest component of secondary injury. Large bioelectric currents immediately enter damaged cells and tissues of guinea pig spinal cords. The driving force behind these currents is the potential difference of adjacent intact cell membranes. For perhaps days, it is the biophysical events caused by trauma that predominate in the early biology of neurotrauma.

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The enormous bioelectric current, carried in part by free calcium, is the major initiator of secondary injury processes and causes significant damage after breach of the membranes of vulnerable cells adjacent to the injury site. The large intra-cellular voltages, polarized along the length of axons in particular, are believed to be associated with zones of organelle death, distortion, and asymmetry observed in acutely injured nerve fibers. These data enlarge our understanding of secondary mechanisms and provide new ways to consider interfering with this catabolic and progressive loss of tissue.