Possible mechanisms underlying effects of N-uronoyl derivatives of amino acids on electrical activity in snail neurons |
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Authors: | I I Korenyuk M Yu Ravaeva |
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Institution: | (1) Vernadskii Tavricheskii National University, Simferopol’, Autonomic Republic of Crimea, Ukraine |
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Abstract: | Using intracellular recording, we studied the effects of N-uronoyl derivatives of an amino acid and peptides (1,2:3,4-di-O-isopropylidene-αa-D-galactopyranuronoyl)-β-alanine
(DAGU-Ala), DAGU-glycyl-glycine (DAGU-Gly-Gly), DAGU-glycyl-D,L-glutamic acid (DAGU-Gly-Glu), as well as of 1,2:3,4-di-O-isopropylidene-αa-D-galactopyranosyluronic
acid (DAGU itself), β-alanine (β-Ala), D,L-glutamic acid (D,L-Glu), and glycyl-glycine (Gly-Gly), which were added to the
extracellular milieu, on the electrical activity of PPa1 and PPa2 neurons and unidentified neurons of Helix albescens Rossm. DAGU-Gly-Gly applied in concentrations of 10−4 to 10−2 M hyperpolarized the membrane in a dose-dependent manner and decreased insignificantly the amplitude of action potentials
(APs). Applications of DAGU-Ala, β-Ala, DAGU-Gly-Glu, D,L-Glu, and Gly-Gly in the same doses resulted in a shift of the membrane
potential toward depolarization and in a drop in the amplitude of APs. Measurements of the first AP derivatives showed that
all the above-mentioned substances suppressed in a concentration-dependent manner both inward and outward transmembrane ion
currents. In this case, DAGU suppressed both inward and outward currents, while DAGU-Ala, β-Ala, DAGU-Glu, D,L-Glu, and Gly-Gly
inhibited predominantly the outward potassium ion current; DAGU-Gly-Gly inhibited inward sodium and potassium ion currents.
Results of a comparative analysis of the neurotropic action of the tested amino acids and their N-uronoyl derivatives showed
that modification of the molecules of neurotransmitter amino acids leads to a decrease in their neurotoxicity and to an increase
in their membranotropic properties.
Neirofiziologiya/Neurophysiology, Vol. 38, Nos. 5/6, pp. 416–425, September–December, 2006. |
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Keywords: | molluscan neurons potentials transmembrane ion currents N-uronoyl derivatives of amino acids |
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