Effect of exogenous nitric oxide on electrogenesis in myelinated and unmyelinated nerve fibers.
Extracellular recording was used to study the effect of sodium nitroprusside, a donor of NO, on parameters of action potential and ionic currents in single sciatic nerve fibers and unmyelinated nerve terminals in the sternal muscle in frogs. Sodium nitroprusside significantly decreased the duration of action potential in Ranvier node and the amplitude of afterdepolarization. In motor nerve terminals bathed in low Ca(2+) saline, sodium nitroprusside increased phase III amplitude of the nerve terminal response corresponding to outward potassium currents. Blockade of voltage-dependent potassium channels with 4-aminopyridine abolished the effects of NO. These data indicate that exogenous NO reduced the duration of action potential and afterdepolarization through enhancement of voltage-dependent potassium currents.
Zefirov
A L
AL
Department of Normal Physiology, Kazan State Medical University.
Katalymov
L L
LL
Usmendeeva
I V
IV
Khaliullina
R R
RR
D000200:Action Potentials / Q000187:drug effects*; D000818:Animals; D017136:Ion Transport / Q000187:drug effects; D009413:Nerve Fibers, Myelinated / Q000187:drug effects / Q000502:physiology; D009569:Nitric Oxide / Q000494:pharmacology* / Q000502:physiology; D020030:Nitric Oxide Donors / Q000494:pharmacology; D009599:Nitroprusside / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology; D011895:Rana ridibunda; D012584:Sciatic Nerve / Q000187:drug effects* / Q000502:physiology*
D020030:Nitric Oxide Donors; D015221:Potassium Channels; D009599:Nitroprusside; D009569:Nitric Oxide