The effects of ferric iron on voltage-gated potassium currents in molluscan neurons.
In isolated neurons of Helix pomatia, a two-microelectrode voltage clamp technique was used to study the effect of Fe3+ on voltage-gated potassium currents: a low-threshold fast-inactivating current (I(A)) and a high threshold slow-inactivating current with calcium-dependent (I(C)) and calcium-independent (I(DR)) components. Extracellular application of FeCl3 rapidly, reversibly and dose-dependently reduced the amplitude of I(A), I(C) and I(DR) with IC50 values of 49, 45 and 70 microM, respectively. Complete inhibition of K+ currents was reached at 100-500 microM Fe3+. The threshold for the total slow-inactivating potassium current shifted in a positive direction by 10-30 mV in the presence of Fe3+ (50-300 microM). Our work is the first demonstration of the strong blocking effect of Fe3+ on potassium currents of neuronal membrane.
Bukanova
Julia V
JV
Department of Brain Research, Institute of Neurology, Russian Academy of Medical Sciences, Moscow, Russia. bukanovaj@mail.ru
Solntseva
Elena I
EI
Skrebitsky
Vladimir G
VG
D000818:Animals; D002118:Calcium / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D004558:Electric Stimulation / Q000379:methods; D005290:Ferric Compounds / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects* / Q000502:physiology / Q000528:radiation effects; D009474:Neurons / Q000502:physiology* / Q000528:radiation effects; D018408:Patch-Clamp Techniques / Q000379:methods; D024642:Potassium Channels, Voltage-Gated / Q000502:physiology*; D012908:Snails / Q000166:cytology
D005290:Ferric Compounds; D024642:Potassium Channels, Voltage-Gated; D002118:Calcium