title: Interaction between bradykinin and voltage-sensitive sodium channels in myelinated nerve fibers.
abstract: The effects of externally and internally applied bradykinin on the excitability of single myelinated nerve fibers were studied. External bradykinin (10 microM) slightly prolongs the action potential of a single myelinated nerve fiber; hence, when the fibers are stimulated by long-lasting pulses, this raises the frequency of repetitive firing in sensory fibers and evokes repetitive activity in motor fibers. Under voltage-clamp conditions, sodium channel inactivation is slowed, while sodium channel activation remains unaffected. Prolonged depolarization of the membrane leads to a maintained sodium current. The voltage dependence of the steady-state sodium current inactivation (h infinity) is shifted in the depolarized direction by approximately 10 mV. Internally applied bradykinin produces a frequency-dependent block of the sodium current. The phenomena described here imply that more than one site on the sodium channel is modified by bradykinin.
authors.affiliation: Institute of Pharmacology, Medical Faculty, University of Bari, Italy.
authors.forename: M R
authors.initials: MR
authors.lastname: Carratù
authors.forename: D
authors.initials: D
authors.lastname: Mitolo-Chieppa
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001920:Bradykinin / Q000494:pharmacology*; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D004553:Electric Conductivity; D004558:Electric Stimulation; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects; D009413:Nerve Fibers, Myelinated / Q000187:drug effects / Q000502:physiology*; D011893:Rana esculenta; D012584:Sciatic Nerve / Q000502:physiology; D015222:Sodium Channels / Q000187:drug effects / Q000502:physiology
chemical_list: D015222:Sodium Channels; D001920:Bradykinin