Enhancement of frog gustatory response by transition metal ions

Kashiwagura, Tadashi; Kamo, Naoki; Kurihara, Kenzo; Kobatake, Yonosuke

doi:10.1016/0006-8993(78)90920-4

Cited by 9 publications

(9 citation statements)

References 8 publications

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“…Their explanation for reduction of the enhanced responses to 100 mM NaCl by the presence of 1 mM CaCl 2 is that CaCl 2 contained in NaCl-stimulating solution increases the amount of membrane-bound calcium and thereby responses to NaCl are reduced to the original level. Addition of NiCl 2 to the NaCl-stimulating solution also enhanced the response to NaCl (Kashiwagura et al 1978). The enhanced response immediately returned to the original level when Ni 2+ was removed from stimulating solutions.…”

Section: Introductionmentioning

confidence: 88%

“…The enhancing effect of NiCl 2 was reversible. Hence, it is unlikely that enhancement of the response to NaCl by NiCl 2 is associated with removal of Ca 2+ from the receptor membrane (Kashiwagura et al 1978). Kitada (1994d) found that water fibers of the frog GL exhibit an enhancement of the responses to CaCl 2 , MgCl 2 , and NaCl by the presence of Ni 2+ to different extents.…”

Section: Introductionmentioning

confidence: 99%

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Mechanism of Enhancement of the Responses of the Frog Glossopharyngeal Nerve to Electrolytes by Enhancers

2008

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In frogs, the responses of the glossopharyngeal nerve (GL) to NaCl are enhanced after treatment of the tongue with 8-anilino-1-naphthalene-sulfonic acid (ANS), a hydrophobic probe for biological membranes. The enhancement by ANS treatment has been explained by removal of Ca2+ from the receptor membrane treated with ANS. To explore the mechanism of enhancement by ANS treatment, we recorded neural responses from the frog GL. After ANS treatment, treatment with 10 mM CaCl2 prior to stimulation of NaCl did not affect the enhanced responses to 100 mM NaCl. The response to a relatively high concentration of CaCl2 (50 mM) was enhanced after ANS treatment. It is difficult to interpret these neural events in terms of modulation of the responses by membrane-bound calcium. The presence of NiCl2 in stimulating solution is known as an enhancer. Neural events after ANS treatment were similar to those caused by NiCl2. Our previous studies have demonstrated that enhancement of the responses to electrolytes by NiCl2 is due to modulation of the responses of water fibers in the GL. Water fibers are characterized by sensitivity to water or CaCl2, and they also respond to relatively high concentrations of electrolytes such as NaCl and choline Cl. Using a suction electrode method, we recorded unitary impulses from single water fibers. The ANS treatment led greatly enhanced responses to NaCl or choline Cl in water fibers, suggesting that enhancement by the ANS treatment is due to modulation of the responses of water fibers as well as enhancement by NiCl2. It appears that distinct receptors for each separate cation responsible for the neural responses in water fibers interact with a membrane element that is affected by ANS or Ni2+.

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Section: Introductionmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Mechanism of Enhancement of the Responses of the Frog Glossopharyngeal Nerve to Electrolytes by Enhancers

2008

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“…The larger reduction in QHCI response by CuCl2 and ZnC12 than that by other metal ions may be due to a greater binding affinity of Cu2+ and Zn2+ to membrane phospholipids than other metal ions (BLAUSTEIN, 1967), since it has been pointed out that lipophilicity is an important parameter in inducing a bitter taste (KURIHARA and KOYAMA, 1972;GARDNER, 1979). KASHIWAGURA et al (1978) reported marked enhancement of frog glossopharyngeal nerve responses to NaCI, KCI, NH4C1, and MgC12 by addition of 1 mM NiCl2, CoCl2, or MnCl2. In our study, however, most of the metal salts at 1 mM slightly inhibited response to NaCI.…”

Section: Discussionmentioning

confidence: 99%

Inhibitory effects of some heavy metal ions on taste nerve responses in mice.

Iwasaki¹,

Satō²

1984

Jpn.J.Physiol

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Effects of treating the tongue with 7 heavy metal salts on chorda tympani nerve responses to sweet, salty, sour, and bitter stimuli were studied in ddy mice. CuCl2 and ZnC12 at 10-5 M inhibited responses to sucrose and Na saccharin without affecting responses to the other taste stimuli. Inhibition of responses to sweet stimuli was reversible, but recovery was very slow. No such selective inhibition of sweet responses was observed with FeSO4, MnC12, CoC12, NiC12 or CdCl2. FeSO4 (1 mM) had a very small effect on all responses. CdC12 (1 mM) depressed responses to all the stimuli to some extent. MnCl2, CoCl2, and NiCl2 (1 mM) slightly inhibited responses to NaCI and quinine hydrochloride, but not HCI. Responses to sweet stimuli were slightly inhibited by 1 mM MnC12 or CoCl2. Kinetic analyses of the inhibition of sucrose responses by CuCl2 indicate that it is a competitive inhibition. Based on the results it is hypothesized that Cu2+ and possibly Zn2+ also compete with sweet-tasting molecules for receptor proteins while other heavy metal ions do not possess a strong ability to bind to the proteins.

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“…Moreover, a receptor, X Na , that is affected by a complex between a Ni 2+ -binding element and a Ni 2+ ion is indicated as X^. Since the enhancing effect of Ni 2+ ions was saturated at 1 mM (Kashiwagura et al, 1978;Kitada, 1994b), it is likely that most X Na is changed to X^ in the presence of 1 mM NiCl 2 . In the present analysis, we also assumed that the magnitude of the neural response (/?)…”

Section: Figurementioning

confidence: 99%

“…Transition metal ions, such as Ni 2+ , Co 2+ and Mn 2+ ions, at concentrations below 5 mM are barely effective in producing nerve impulses in the water fibers of the frog glossopharyngeal nerve (Kitada, 1990(Kitada, , 1994b. However, they have enhancing effects on the responses to Ca 2+ (Kitada, 1994b, c), Mg 2+ (Kashiwagura et ai, 1978;Kitada, 1994b) and Na + (Kashiwagura et al, 1978;Herness, 1987Herness, , 1991Kitada, 1994b) ions. Transition metal ions do not affect antagonism between Ca 2+ and Mg 2+ ions and between Ca 2+ and Na + ions in the neural responses to a mixture of two salts (Kitada, 1994b).…”

Section: Introductionmentioning

confidence: 99%

A Quantitative Study of the Enhancing Effect of Nickel Ions on the Taste Response to Sodium Ions of Single Fibers of the Frog Glossopharyngeal Nerve: Competitive Inhibition by Calcium Ions of the Nickel-Enhanced Response to Sodium Ions

Kitada

Mitoh

1996

Chem Senses

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Single water fibers of the frog glossopharyngeal nerve respond to relatively high concentrations of NaCl ( > 80 mM). NiCl2 at 1 mM enhanced the Na+ response and reduced the threshold concentration for NaCl to 20 mM. CaCl2 at 0.5-1 mM induced an inhibition of the Ni2+ -enhanced response to Na+ ions. A quantitative explanations for these results is provided by the hypothesis that Ni2+ ions secondarily affect a sodium receptor or channel (designated XNa*) that is responsible for the Na+ response and that Ca2+ ions inhibit the Ni2+ -enhanced response to Na+ ions by competing with Na+ ions for XNa*. Double-reciprocal plots of the experimental data indicate that the affinity of XNa* for both Na+ ions (agonist) and Ca2+ ions (competitive antagonist) in the presence of 1 mM NiCl2 was five times higher than the previously reported values obtained in the absence of NiCl2 (Kitada, 1991). Ni2+ ions at 1 mM enhanced the maximal response to Na+ ions by 190%. It appears that a sodium receptor (or channel) interacts with a Ni2+ -binding element that is affected by Ni2+ ions and, thus, Ni2+ ions can induce both an increase in the affinity of the sodium receptor for the respective cations and an enhancement of the Na+ response.

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Enhancement of frog gustatory response by transition metal ions

Cited by 9 publications

References 8 publications

Mechanism of Enhancement of the Responses of the Frog Glossopharyngeal Nerve to Electrolytes by Enhancers

Mechanism of Enhancement of the Responses of the Frog Glossopharyngeal Nerve to Electrolytes by Enhancers

Inhibitory effects of some heavy metal ions on taste nerve responses in mice.

A Quantitative Study of the Enhancing Effect of Nickel Ions on the Taste Response to Sodium Ions of Single Fibers of the Frog Glossopharyngeal Nerve: Competitive Inhibition by Calcium Ions of the Nickel-Enhanced Response to Sodium Ions

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