Calcium channels as target sites of heavy metals.
Zinc (Zn), aluminium (Al), mercury (Hg), methylmercury (MeHg) and lead (Pb) extracellulary applied reduce voltage-activated calcium channel currents (VACCCs); Pb and Al also reduce N-methyl-D-aspartate (NMDA)-activated channel currents (NACCs). Pb is most effective in reducing VACCCs, with an IC50 of 0.46 microM, followed by Hg (IC50 = 1.1 microM) and MeHg (IC50 = 2.6 microM). Zn and Al were less potent (IC50 = 69 and 84 microM, respectively). Al acts on channels in the open state; its effect is pH dependent. The effects of Pb were specific for VACCCs and NACCs. Hg, Al and Zn had only minor effects on voltage-activated potassium and sodium channels, while MeHg reduced potassium channel currents (IC50 = 2.2 microM) and, at higher concentrations, sodium channel currents (IC50 = 12.3 microM). Al also reduced other receptor-activated channel currents. These results demonstrate that a variety of metal species produce different actions at the level of the cell membrane.
Büsselberg
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Heinrich Heine-University Düsseldorf, Germany.
D000535:Aluminum / Q000633:toxicity; D000818:Animals; D015220:Calcium Channels / Q000187:drug effects*; D002462:Cell Membrane / Q000187:drug effects; D002478:Cells, Cultured; D007854:Lead / Q000633:toxicity; D008628:Mercury / Q000633:toxicity; D008670:Metals / Q000633:toxicity*; D016202:N-Methylaspartate / Q000494:pharmacology; D051381:Rats; D015032:Zinc / Q000633:toxicity
D015220:Calcium Channels; D008670:Metals; D007854:Lead; D016202:N-Methylaspartate; D000535:Aluminum; D008628:Mercury; D015032:Zinc