Effect of sympathectomy on extracellular potassium ionic activity and blood flow in experimental spinal cord contusion.

摘要: Contusion injury of cat spinal cords causes a rapid loss evoked potential transmission across the impact site. We have previously shown that this initial action conduction is transient and recovers partially within an hour after injury, often diminishing 2–4 h later when white matter blood flow decreases from pre-injury levels of< 12ml/100 g/min to< 6ml/100 g/min. The delayed potentials are not well understood. Although K+ release has been suggested to cause blockade in neither nor time course shifts shown. We used K+-selective microelectrodes record extracellular activity contused thoracic matter, comparing changes with recovery somatosensory-evoked local measured by hydrogen clearance technique. If plays role loss, should rapidly increase sufficient block clear relating recovery. paravertebral sympathetic ganglia were ablated some cats, procedure which we prevent post-traumatic ischemia potentials. K+, observe untreated injured cats but sympathectomized cats. In 5 subjected 400 g·cm contusions, lateral columns rose normal (3–4 mM) mean 54 mM, clearing exponential half-time 45 min. In 47 35 injured, did change significantly. all lost contusion recovered at 1–2 normalization K+. Extracellular again transcend 15 mM even below 6 ml/100 Blood fell only returned 15mM. The magnitude can thus account for pattern contusion. However, cannot be related increases With exception slightly faster rate, found no dramatic differences behavior between cats. finding fall until suggests ionic derangements may vasoconstriction first injury.