Sensitivity to 4-aminopyridine observed in mammalian sciatic nerves during acute pyridoxine-induced sensory neuropathy and recovery.
In vitro physiologic properties of rat sciatic nerve were examined during pyridoxine-induced sensory neuropathy and following recovery. Compound action potential waveform characteristics, recovery cycle properties during paired stimulation, and ability to follow stimuli presented at high frequencies were examined. All parameters were assessed before and after potassium channel blockade with 4-aminopyridine in nerves from acutely toxic, recovered, and age-matched control rats. Compound action potential waveforms recorded from acutely toxic nerves were less affected by application of 4-aminopyridine than were those recorded from control nerves. Recovery cycles were less prolonged and frequency-following abilities less compromised a 3-month recovery period, experimental nerves demonstrated a more pronounced sensitivity to 4-aminopyridine than did age-matched control nerves. It is proposed that these differences in the physiological effects of 4-aminopyridine reflect the selective loss of large-caliber sensory fibers during the acute toxic phase and the increased sensitivity to the drug of regenerated sensory fibers following recovery.
Bowe
C M
CM
Section of Neurobiology, Brown University, Providence, Rhode Island 02912.
Veale
K
K
D015761:4-Aminopyridine; D000200:Action Potentials / Q000187:drug effects; D000208:Acute Disease; D000631:Aminopyridines / Q000494:pharmacology*; D000818:Animals; D005260:Female; D009413:Nerve Fibers, Myelinated / Q000473:pathology; D009422:Nervous System Diseases / Q000139:chemically induced / Q000473:pathology / Q000503:physiopathology*; D011736:Pyridoxine; D051381:Rats; D011919:Rats, Inbred Strains; D011930:Reaction Time; D012584:Sciatic Nerve / Q000187:drug effects* / Q000473:pathology; D012677:Sensation; D013126:Spinal Nerve Roots / Q000473:pathology
D000631:Aminopyridines; D015761:4-Aminopyridine; D011736:Pyridoxine