TY - JOUR
T1 - Enhancing effect of nickel ions on the response to magnesium ions of single fibers of the frog glossopharyngeal nerve
T2 - Competitive inhibition by calcium ions of the nickel-enhanced response to magnesium ions
AU - Kitada, Yasuyuki
AU - Mitoh, Yoshihiro
N1 - Copyright:
Copyright 2007 Elsevier B.V., All rights reserved.
PY - 1997/12
Y1 - 1997/12
N2 - Single fibers of the frog glossopharyngeal nerve respond to MgCl2 at concentrations exceeding 10 mM. NiCl2 at 1 mM enhanced the Mg2+ response. CaCl2 at 0.5-2 mM induced an inhibition of the Ni2+-enhanced response to Mg2+ ions. A quantitative explanation for these results is provided by the hypothesis that Ni2+ ions secondarily affect a magnesium receptor (designated X(*)(Mg)) that is responsible for the Mg2+ response and that Ca2+ ions inhibit the Ni2+-enhanced response to Mg2+ ions by competing with Mg2+ ions for X(*)(Mg). Double-reciprocal plots of the experimental data indicate that Ni2+ ions do not affect the affinities of X(*)(Mg) for both Mg2+ ions (agonist) and Ca2+ ions (competitive antagonist) appreciably, and that Ni2+ ions at 1 mM enhanced the maximal response to Mg2+ ions by 270%. It appears that a magnesium receptor interacts with an Ni2+-binding element that is affected by Ni2+ ions and, thus, Ni2+ ions can induce an enhancement of the Mg2+ response.
AB - Single fibers of the frog glossopharyngeal nerve respond to MgCl2 at concentrations exceeding 10 mM. NiCl2 at 1 mM enhanced the Mg2+ response. CaCl2 at 0.5-2 mM induced an inhibition of the Ni2+-enhanced response to Mg2+ ions. A quantitative explanation for these results is provided by the hypothesis that Ni2+ ions secondarily affect a magnesium receptor (designated X(*)(Mg)) that is responsible for the Mg2+ response and that Ca2+ ions inhibit the Ni2+-enhanced response to Mg2+ ions by competing with Mg2+ ions for X(*)(Mg). Double-reciprocal plots of the experimental data indicate that Ni2+ ions do not affect the affinities of X(*)(Mg) for both Mg2+ ions (agonist) and Ca2+ ions (competitive antagonist) appreciably, and that Ni2+ ions at 1 mM enhanced the maximal response to Mg2+ ions by 270%. It appears that a magnesium receptor interacts with an Ni2+-binding element that is affected by Ni2+ ions and, thus, Ni2+ ions can induce an enhancement of the Mg2+ response.
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U2 - 10.1093/chemse/22.6.613
DO - 10.1093/chemse/22.6.613
M3 - Article
C2 - 9455608
AN - SCOPUS:0031435345
VL - 22
SP - 613
EP - 622
JO - Chemical Senses
JF - Chemical Senses
SN - 0379-864X
IS - 6
ER -