Total cell associated electrolyte homeostasis in rat spinal cord cells following apparently irreversible injury

Abstract

Background: We investigated total electrolyte homeostasis in spinal cord cells of rats subjected to irreversible spinal cord trauma.

Material/methods: Forty-two rats underwent total transection of spinal cord (Group 1); chemical neurolysis by 10% lidocaine overdose (Group 2); sham "injury" (Group 3). Spinal cords were isolated 24 h, 72 h or 7 days following injury. Total cellular Ca, Mg, Na and K were measured in the spinal cord thoracic or lumbar parts using an atomic absorption spectrometer.

Results: Group 1: A significant Ca, Mg, Na, and K efflux was observed in thoracic and lumbar parts 24 h following transection. By 72 h, a significant re-entrance of Ca was evident. By 168 h, an influx of all electrolytes was demonstrable, sometimes reaching concentrations above the pre-trauma levels. Group 2: Following 24 h, Na, K, Ca, and Mg concentrations dropped significantly both in thoracic and lumbar parts. By 72 h, the electrolyte re-entrance was evident in the thoracic, but not the lumbar part. By 168 h, Na, K, Ca, and Mg influx was observed both in thoracic and lumbar parts, the concentration approaching pre-trauma levels. Group 3: No changes in electrolyte content were observed in spinal cords of sham-operated animals.

Conclusions: Following massive, apparently irreversible injury of the spinal cord, some restorative processes do take place at the cellular level. Subsequent supernormal accumulation of intracellular electrolytes, especially Ca, might eventually contribute to a secondary injury. Should this be the case, pharmacotherapeutic intervention might prove beneficial.