1980
DOI: 10.1113/jphysiol.1980.sp013393
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Effects of some heavy metal ions on the ionic currents of myelinated fibres from Xenopus laevis.

Abstract: 1. The effect of the heavy metal ions Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+ and Hg2+ on permeability parameters of the nerve membrane was investigated. The ions were applied externally to single myelinated fibres of Xenopus laevis. The ionic currents, associated with potential steps were measured and analysed. 2. Zn2+ reversibly slowed down the kinetics of the K system. The effect at large potential steps was described as an increase of tau n. 3.4 mM-Zn2+ increased tau n about three times. 3. Ni2+ and Cu2+ also r… Show more

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Cited by 60 publications
(47 citation statements)
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“…Such an action is known for certain divalent cations (e.g. Arhem, 1980) and has been mentioned 623 in passing for Mn2 by Hille, Woodhull & Shapiro (1975). The kinetics of the TTX-sensitive and TTX-resistant currents of these cells remain to be investigated in physiological concentrations of divalent cations.…”
Section: Kinetics Of the Sodium Currentsmentioning
confidence: 99%
“…Such an action is known for certain divalent cations (e.g. Arhem, 1980) and has been mentioned 623 in passing for Mn2 by Hille, Woodhull & Shapiro (1975). The kinetics of the TTX-sensitive and TTX-resistant currents of these cells remain to be investigated in physiological concentrations of divalent cations.…”
Section: Kinetics Of the Sodium Currentsmentioning
confidence: 99%
“…V 1/2 has been shown to depend on the existence of certain charged residues on the external surface of the channel protein (11)(12)(13), suggesting these charges contribute to an electric potential at the external surface (14)(15)(16). Metal ions were early recognized to alter the excitability of neurons by shifting the G(V) curve of ion channels along the voltage axis (17)(18)(19)(20). For certain metal ions most of this effect is likely to be caused by screening (i.e., damping the electric field by mobile charges rather than by bound charges) of the critical negative charges at the external surface of the channel protein, modifying 4 out at the voltage sensor (14,15,20).…”
Section: Introductionmentioning
confidence: 99%
“…It is likely that it also involves competition of Zn2+ with sweet stimuli for binding to receptor proteins, but the action of Zn2+ appears to be more complicated than that of Cu2 + The tendency of metal ions to form complexes with an organic ligand varies according to the Irving-Williams series (FIABANE and WILLIAMS, 1977). The stability constant for the formed complex increases as Mn2+ <Fe2+ <Co2+ <Ni2+ < Cu2 + > Zn2 + (see ARHEM, 1980). In our experiments, Cu2 + and Zn2 + produced marked inhibition of sweet responses compared with the other metal ions.…”
Section: Discussionmentioning
confidence: 50%
“…The relative binding constant for ions with SH-groups has been reported to be Cd2 + > Zn2 + (see ARHEM, 1980), which is the reverse of their inhibitory effectiveness. Therefore, our results cannot be explained entirely by the hypothesis that SH-groups are mainly involved in the taste reception (YUR'EVA, 1957).…”
Section: Discussionmentioning
confidence: 99%