Excitotoxicity
of Lathyrus Sativus Neurotoxin in Leech Retzius
Neurons
D.
CEMERIKIĆ, V. NEDELJKOV, S. LOPIČIĆ, S.
DRAGOVIĆ, B. BELESLIN
Department of Pathological Physiology, Medical
Faculty, Belgrade, Yugoslavia
Received April 13, 2000
Accepted August 16, 2000
Summary
The effects of Lathyrus sativus neurotoxin were
studied on the cell membrane potential and
cellular cation composition in Retzius nerve
cells of the leech Haemopis sanguisuga, with
ion-selective microelectrodes using liquid
ion-exchangers. Bath application of 10-4 mol/l
Lathyrus sativus neurotoxin for 3 min depolarized
the cell membrane potential and decreased the
input resistance of directly polarized membrane
in Retzius neurons. At the same time the cellular
Na+ activity increased and cellular K+ activity
decreased with slow but complete recovery, while
the intracellular Ca2+ concentration was not
changed. Na+-free Ringer solutions inhibited the
depolarizing effect of the neurotoxin on the cell
membrane potential. Zero-Ca2+ Ringer solution or
Ni2+-Ringer solution had no influence on the
depolarizing effect of the neurotoxin on the cell
membrane potential. It is obvious that the
increase in membrane conductance and
depolarization of the cell membrane potential are
due to an influx of Na+ into the cell accompanied
by an efflux of K+ from the cell.
Key
words
Input membrane resistance ·
Intracellular Ca2+ concentration · Intracellular
Na+ and K+ activities · Lathyrus sativus
excitotoxicity · Leech Retzius neurons
Reprint requests
Dusan Cemerikic, Department of
Pathological Physiology, Medical Faculty, Dr
Subotica 1/II, 11000 Belgrade, Yugoslavia. Fax: +
381-11-684 053, E mail: beleslin@afrodita.rcub.bg.ac.yu
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