4-Aminopyridine and dendrotoxin induce repetitive firing in rat visceral sensory neurones by blocking a slowly inactivating outward current.

摘要: In a subpopulation of rat visceral afferent neurones we have identified potassium (K) current which is novel to mammalian neurones. It activates rapidly at potentials positive - 70 mV but shows only slow and incomplete inactivation inhibited by 1-30 microM 4-aminopyridine (4-AP) or 3-10 nM dendrotoxin (DTX). Inhibition this slowly inactivating suppresses spike adaptation leads pronounced repetitive firing. contrast, other possessing the normal transient A-current were insensitive 4-AP concentrations below 100 microM. We suggest that inhibition may contribute convulsant actions DTX.