Mechanism of the electric response of lipid bilayers to bitter substances

Naito, Makio; Sasaki, Naoyuki; Kambara, Takeshi

doi:10.1016/s0006-3495(93)81159-7

Cited by 10 publications

(1 citation statement)

References 33 publications

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“…Consequently, the increase in bisoxonol fluorescence intensity measured on the addition of lindane to spermatozoa in which ∆Ψ had been collapsed by 120 mM K + could reasonably be ascribed to a change in Ψ D . Earlier data showing that various membrane-active compounds alter the dipole potential in lipid bilayers lend further support to this hypothesis [49][50][51]. The evidence that the insecticide was still able to induce an increase in [Ca# + ] i in depolarizing conditions suggest that Ψ D modifications may affect the conductance of membrane ion channels, as previously surmised on theoretical grounds [52,53].…”

Section: Discussionmentioning

confidence: 58%

Partition of the organochlorine insecticide lindane into the human sperm surface induces membrane depolarization and Ca2+ influx

Silvestroni

Fiorini

Palleschi

1997

Biochemical Journal

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The effects of the insecticide lindane (the gamma-isomer of 1,2,3,4,5,6-hexachlorocyclohexane) on membrane potential, cytosolic free Ca2+ concentration ([Ca2+]i) and surface biophysical properties were studied in human spermatozoa. The insecticide induces rapid, transient and reproducible membrane depolarization and opening of voltage-dependent Ca2+ channels leading to an increase in [Ca2+]i. In contrast with the effect in somatic cells, lindane did not affect gamma-aminobutyric acid receptor-linked Cl- currents. Ca2+ and K+ currents were found to drive lindane-induced membrane depolarization and repolarization respectively, whereas Na+ and Cl- fluxes appear not to have a role in the phenomenon. The insecticide was still able to produce membrane depolarization both in the combined absence of extracellular Ca2+ and Na+ and in high-K+ buffer, suggesting that lindane alters the membrane dipole potential. In agreement with this, Laurodan and Prodan fluorescence spectroscopy revealed that lindane partition into the sperm plasma membrane lowers water molecular dynamics in the uppermost region of the membrane external leaflet, probably as the result of reordering of water dipoles. We propose that the first effect of lindane partitioning into the sperm plasma membrane is a change in the membrane dipole potential, which results in the activation of membrane-located Ca2+-influx pathways.

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Section: Discussionmentioning

confidence: 58%

Partition of the organochlorine insecticide lindane into the human sperm surface induces membrane depolarization and Ca2+ influx

Silvestroni

Fiorini

Palleschi

1997

Biochemical Journal

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Electrophysiological actions of quinine on voltage-dependent currents in dissociated rat taste cells

Chen

Herness

1997

Pfl�gers Archiv European Journal of Physiology

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How taste receptor cells participate in encoding disparate compounds into distinct taste qualities represents a fundamental problem in the study of gustatory transduction mechanisms. Quinine is the most common stimulus employed to represent bitterness yet its electrophysiological consequences on voltage-dependent ion channels in the taste receptor cell have not been elucidated in detail. This study examines such effects on taste receptor cells dissociated from the foliate and circumvallate papillae of the rat. Outward potassium currents, which include transient, sustained and calcium-activated components, were reversibly inhibited by bath application of quinine, with an IC50 of 5.1x10(-6)M. The time course of the current traces, along with voltage shifts in normalized conductance and inactivation curves, suggests that multiple mechanisms of inhibition may be occurring. Inwardly rectifying potassium currents were unaffected. Sodium currents, to somewhat higher concentrations of quinine (IC50 = 6.4x10(-5)M), were also reduced in magnitude without noticeable effects on activation or reversal potential but with a shift in inactivation. Calcium currents, visualized with barium as a charge carrier, were enhanced in magnitude by the presence of low concentrations of quinine (10(-5)M) but were suppressed by higher concentrations (10(-4)M). Quinine broadened the waveform of the gustatory action potential and increased the input resistance. These data serve as genesis to future investigations of the signal transduction mechanism of quinine on voltage-dependent currents.

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Responses of the hamster chorda tympani nerve to binary component taste stimuli: evidence for peripheral gustatory mixture interactions

Formaker

Frank

1996

Brain Research

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Studies of taste mixtures suggest that stimuli which elicit different perceptual taste qualities physiologically interact in the gustatory system and thus, are not independently processed. The present study addressed the role of the peripheral gustatory system in these physiological interactions by measuring the effects of three heterogeneous taste mixtures on responses of the chorda tympani (CT) nerve in the hamster (Mesocricetus auratus). Binary taste stimuli were presented to the anterior tongue and multi-fiber neural responses were recorded from the whole CT. Stimuli consisted of a concentration series of quinine.HCl (QHCl: 1-30 mM), sodium chloride (NaCl: 10-250 mM), sucrose (50-500 mM) and binary combinations of the three different chemicals. Each mixture produced a unique pattern of results on CT response magnitudes measured 10 s into the response. Sucrose responses were inhibited by quinine in QHCl-sucrose mixtures. Neural activity did not increase when quinine was added to 50-250 mM NaCl in QHCl-NaCl mixtures. However, the neural activity elicited by sucrose-NaCl mixtures was greater than the activity elicited by either component stimulus presented alone. The results demonstrate that gustatory mixture interactions are initiated at the level of the taste bud or peripheral nerve. Mechanisms for these interactions are unknown. The results are consistent with one component stimulus modifying the interaction of the other component stimulus with its respective transduction mechanism. Alternatively, peripheral inhibitory mechanisms may come into play when appetitive and aversive stimuli are simultaneously presented to the taste receptors.

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Mechanism of the electric response of lipid bilayers to bitter substances

Cited by 10 publications

References 33 publications

Partition of the organochlorine insecticide lindane into the human sperm surface induces membrane depolarization and Ca2+ influx

Partition of the organochlorine insecticide lindane into the human sperm surface induces membrane depolarization and Ca2+ influx

Electrophysiological actions of quinine on voltage-dependent currents in dissociated rat taste cells

Responses of the hamster chorda tympani nerve to binary component taste stimuli: evidence for peripheral gustatory mixture interactions

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