Electrophysiological effects of 4-aminopyridine on fictive locomotor activity of the rat spinal cord in vitro.
Recently the K+ channel blocker 4-aminopyridine (4-AP) has been suggested to be useful to improve motor deficits due to spinal cord lesions. There is, however, little basic research support for this action of 4-AP. In this study we have used as a model the neonatal mammalian spinal cord in vitro that generates a rhythmic activity termed fictive locomotion (induced by bath-application of NMDA + 5-HT) with phasic electrical discharges alternating between flexor and extensor motor pools and between left and right motoneurons within the same segment. When 4-AP was added in the presence of sub-threshold concentrations of NMDA + 5-HT, there was facilitation of fictive locomotion which appeared with alternating patterns on all recorded ventral roots (VR). Furthermore, in the presence of 4-AP, weak dorsal root (DR) stimuli, previously insufficient to activate locomotor patterns, generated alternating discharges from various VRs. The present data show that 4-AP could strongly facilitate the locomotor program initiated by neurochemicals or electrical stimuli, indicating that the spinal locomotor network is a very sensitive target for the action of 4-AP.
Neurobiology Sector and INFM Unit, International School for Advanced Studies (SISSA), Trieste, Italy. taccola@sissa.it
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D015761:4-Aminopyridine / Q000008:administration & dosage*; D000818:Animals; D000831:Animals, Newborn; D001683:Biological Clocks / Q000187:drug effects*; D020233:Gait Disorders, Neurologic / Q000188:drug therapy* / Q000209:etiology / Q000503:physiopathology*; D008124:Locomotion / Q000187:drug effects*; D008159:Lumbar Vertebrae / Q000187:drug effects / Q000503:physiopathology; D026902:Potassium Channel Blockers / Q000008:administration & dosage; D051381:Rats; D017208:Rats, Wistar; D013116:Spinal Cord / Q000187:drug effects / Q000503:physiopathology*; D013119:Spinal Cord Injuries / Q000150:complications / Q000188:drug therapy* / Q000503:physiopathology*
D026902:Potassium Channel Blockers; D015761:4-Aminopyridine