Heavy metals regulate physiological and behavioral events by modulating ion channels in neuronal membranes of molluscs
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Abstract
- (1)
The excitability and chemosensitivity of molluscan neurons were modified under the influence of the heavy metals Hg2+, Cd2+, Cu2+, Pb2+ and Zn2+.
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Change in excitability to transmitters occurred as a potentiation or depression of the evoked response both in duration of membrane polarization and in frequency of spike activity.
- (3)
The chemosensitivity changes in various ways, namely:
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excitatory effect was totally eliminated;
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one component of the effect was depressed.
Different neurons may show different reactions to the same heavy metal.
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- (4)
There were differences in the effects of various heavy metals. Hg2+ has a more generalized effect than Cd2+; Cu2+, Pb2+ and Zn2+ were less effective in a number of neurons. The heavy metal effect was dose dependent, too.
- (5)
Both inward and outward currents, which were evoked by neurotransmitters or voltage induced, were modified in most of the tested neurons. Both an increase and decrease of the membrane permeability occurred in different neurons in response to the same or different heavy metals.
- (6)
The changes can be interpreted as a result of
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direct effect on specific ionic channels;
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modification of receptors binding ACh, 5HT, or DA;
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modification of intracellular processes responsible for the regulation of membrane permeability.
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Keywords
Heavy Metal CdCl2 Membrane Permeability CuCl2 ZnCl2Preview
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References
- Kass, R. S., Tsien, R. S., and Weingart, R.: 1978, ‘Ionic Basis of Transient Inward Current Induced by Strophantidin in Cardiac Purkinje Fibers’,J. Physiol. 281, 209–226.Google Scholar
- Levitan, I. B., and Kaczmarek, L. K.: 1987, ‘Ion Currents and Ion Channels: Substrates for Neuromodulation’, in L.K. Kaczmarek and I.B. Levitan (eds.),Neuromodulation, Oxford Univ. Press, N.Y., Oxford, pp. 18–38.Google Scholar
- S.-Rózsa, K., and Salánki, J.: 1985, “Effect of Heavy Metals on the Chemosensitivity of Neural Somata inLymnaea stagnalis’, in J. Salánki (ed.),Heavy Metals in Water Organisms, Akadémiai Kiadó, Budapest, pp. 387–400.Google Scholar
- S.-Rózsa, K., and Salánki, J.: 1987, ‘Excitable Membranes—Object for Evaluating the Effect of Heavy Metal Pollution’,Acta Biol. Acad. Sci. Hung. 38, 31–45.Google Scholar
- S.-Rózsa, K., Salánki, J., and Présing, M.: 1988, ‘Use ofLymnaea stagnalis in Monitoring Heavy Metal Pollution’, in M. Yasuno and B.A. Whitton (eds.),Biological Monitoring of Environmental Pollution, Tokai University Press, pp. 247–255.Google Scholar
- V.-Balogh, Katalin, Salabarria, Fernandez, D., and Salánki, J.: 1988, ‘Heavy Metal Concentrations ofLymnaea stagnalis L. in the Environs of Lake Balaton (Hungary),Wat. Res. 22, 1205–1210).Google Scholar
- Weinreich, D., and Wonderlin, W. F.: 1987, ‘Copper Activates a Unique Inward Current in Molluscan Neurones’,J. Physiol. 394, 429–443.Google Scholar
- Westbrook, G. L., and Mayer, M. L.: 1987, ‘Micromolar Concentrations of Zn2+ Antagonize NMDA and GABA Responses of Hippocampal Neurons’,Nature 328, 640–643.Google Scholar