Українська English

ISSN 2522-9028 (Print)
ISSN 2522-9036 (Online)
DOI: https://doi.org/10.15407/fz

Fiziologichnyi Zhurnal

is a scientific journal issued by the

Bogomoletz Institute of Physiology
National Academy of Sciences of Ukraine

Editor-in-chief: V.F. Sagach

The journal was founded in 1955 as
1955 – 1977 "Fiziolohichnyi zhurnal" (ISSN 0015 – 3311)
1978 – 1993 "Fiziologicheskii zhurnal" (ISSN 0201 – 8489)
1994 – 2016 "Fiziolohichnyi zhurnal" (ISSN 0201 – 8489)
2017 – "Fiziolohichnyi zhurnal" (ISSN 2522-9028)

Fiziol. Zh. 2007; 53(3): 61-69

Prolonged after-potentialsof myelinated nervous fibres ofamphibian after blockage of potas-sium channels by 4-aminopyridine

I.V. Kuznetzova, D.A. Evstigneev, N.V. Gluhova.

    Ecological Foundation, Ulianov Region, Russia



Abstract

Myelinated nerve fibres of Rana ridibunda Pallas were studied by using extra-cellular recording technique. 4-aminopyridine, a blocker of fast potassium channels produced considerable changes in duration of the after-depolarization and increase in total membrane depolarization (evaluated by an action poten- tial area). These effects were time-dependent. The after-depo- larization duration under 4-aminopyridine (4-AP) treatment changes in 3 phases: at the beginning of the exposure its dura- tion increased; then the increase stopped; and later duration of the after-depolarization start to decrease. The last phase was often followed by hyperpolarizing after-potential. The inter- change of these phases accompanies by statistically signifi- cant increase of the action potential area (from 189.201 ± 28.437 mVЧms in normal solution to 489.945 ± 41.75 mVЧms in 5 minutes after 4-AP application). These observations are explained as a result of the increased activation of the slow potassium channels and decreased portion of fast potassium channels involved in membrane repolarization. The decrease in post-tetanic depolarization duration, the appearance of the post-tetanic hyperpolarization at low frequencies and increase of post-tetanic hyperpolarization at higher frequencies of stimulation under 4-AP treatment are dependent on activation of slow potassium channels.

Full text: (PDF, in Ukrainian)

References

  1. Ильин В.И., Катина И.Е., Лонский А.В., Маковский В.С., Полищук Е.В. Компоненты калиевого тока мембраны перехвата Ранвье в условиях фиксации потенциала. – В кн.: Биофизика мембран: Материалыконф. 21–23 сент. 1973 г. – Каунас, 1973. – С. 286–291.
  2. Каталымов Л.Л. Особенности следовой деполя- ризации нерва и одиночного нервного волокна лягушки // Нейрофизиология. – 1974. – 6, № 10. –С. 532–541.
  3. Кузнецова И.В., Евстигнеев Д.А., Глухова Н.В.Изменения электрической активности миелини-зированных нервных волокон амфибий под влиянием 4-аминопиридина // Фiзiол. журн. – 2005. – 51. –№ 2. – С. 96–103.
  4. David G., Modney B., Scappaticci K.A. et al. Electri- cal and morphological factors influencing the depolariz- ing after-potential in rat and lizard myelinated axons //J. Physiol. – 1995. – 489, № 1. – P. 141–157.
  5. Dubois J.M. Evidence for existence of three types of potassium channels in the frog node membrane // Ibid. – 1981. – 318. – P. 279–295.
  6. Dubois J.M. Properties and physiological roles of K+ currents in frog myelinated nerve fibres as revealed by 4-amino pyridine. – In: Aminopyridines and similarly act-ing drugs. – N. Y.: Pergamon press, 1982. – Р. 43–51.
  7. Dubois J.M. Potassium current in the frog node of Ranvier // Prog. Biophys. Molec. Biol. – 1983. – 42. – P. 1–20.
  8. Eng D.L., Gordon T.R., Kocsis J.D., Waxman S.G. Development of 4-AP and TEA sensitivities in mammalian myelinated nerve fibers // J. Neurophysiol. –1988. – 60, № 6. – P. 2168–2179.
  9. 9. Honmou O., Utzshneider D.A., Rizzo M.A. et al. Delayed depolarization and slow sodium current in cutaneous afferents // J. Neurophysiol. – 1994. – 71, № 5. – P. 1627–1637.
  10. 10. Ilyin V.I., Katina I.E., Lonskii A.V. et al. The Cole-Moore effect in nodal membrane of the frog Rana ridibunda: evi-dence for fast and slow potassium channels // J. MembraneBiol. – 1980. – 57. – P. 179–193.
  11. Kocsis J.D., Eng D.L., Gordon T.R., Waxman S.G. Func- tional differences between 4-aminopiridine and tetraethy- lammonium-sensitive potassium channels in myelinated axons // Neurosc. Lett. – 1987. – 75. – P. 193–198.
  12. Kocsis J.D., Ruiz J.A., Waxman S.G. Maturation of mammalian myelinated fibers: changes in action-potential characteristics following 4-aminopiridine application // J. Neurophysiol. – 1983. – 50, № 2. – P. 449–463.
  13. McIntyre C.C., Richardson A.G., Grill W.N. Model- ing the excitability of mammalian nerve fibers: influ-ence of afterpotentials on the recovery cycle // Ibid. –2002. – 87, № 2. – Р. 995–1006.
  14. Poulter M.P., Padjen A.L. Different voltage-dependent potassium conductances regulate action potential repolarization in frog myelinated axon // Neuroscience. –1995. – 68, № 2. – P. 497–504.
© National Academy of Sciences of Ukraine, Bogomoletz Institute of Physiology, 2014-2025.