EFFECT OF 4-AMINOPYRIDINE IN ACUTE SPINAL-CORD INJURY

BACKGROUND The demyelination process has been proven to be an importan t factor contributing to long-term sensory and motor impairments after spinal cord injury (SCI). The loss of myelin promotes exposure of Kchannels in internodal region of the damaged myelinated axons leading to KC efflux into the neurons with subsequent blockage of action poten tials. The potassium channel blocker 4-aminopyridine (4-AP) has been e ffective in restoring some sensory and motor impairment in incomplete SCI patients, The effect of this compound given immediately after an a cute injury is not known. The objective of this study was to determine if blockage of K+ ions efflux immediately after an acute SCI would im prove neuronal conduction in this model of injury. METHODS Cortical so matosensory evoked potentials (SSEPs) were recorded before and after a weight-induced compression injury of 120 grams, and were monitored up to 5 hours postinjury. A randomized treatment was initiated with admi nistration of either vehicle or 4-AP. All 4-AP treatments were given a s intravenous bolus injections of 1.0, 0.5, and 0.3 mg/kg at 1, 2, and 3 hours after the trauma. RESULTS The SSEPs were abolished immediatel y after the injury in all control and treated animals, Both groups sho wed spontaneous recovery of the SSEPs at the rate of 44.5% for the 4-A P treated and nontreated groups at the second hour postinjury, This re covery rate remained the same for both groups at the end of the experi ments. CONCLUSIONS Based on the recovery of the SSEPs, our data indica te that early administration of 4-AP lacks any beneficial effect on ax onal function during acute stage of spinal cord injury.