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M Kashiwayanagi

Publications and source records attributed to M Kashiwayanagi.

At least 19 recordsLinked to original sources
PubMed1995

Odor responses after complete desensitization of the cAMP-dependent pathway in turtle olfactory cells.

The degree of contribution of the cAMP signal transduction pathway to odor responses was examined by recording current responses from isolated turtle olfactory cells under the whole-cell voltage clamp conditions. The cAMP signal transduction pathway was desensitized by dialyzing 1 mM cAMP and 0.5 mM IBMX from the patch pipette into the cells. Extracellular application of 3 mM cpt-cAMP, a membrane-permeable cAMP analogue elicited no response, indicating that the cAMP pathway was completely desensitized. Application of an odorant cocktail induced a large inward current under these conditions, suggesting that the cAMP-independent signal transduction contributes significantly to generation of odor responses in the turtle.

1-Methyl-3-isobutylxanthine↗
PubMed1995

Intracellular injection of inositol 1,4,5-trisphosphate increases a conductance in membranes of turtle vomeronasal receptor neurons in the slice preparation.

Inositol 1,4,5-trisphosphate (IP3) was injected into turtle vomeronasal receptor neurons in the slice preparation under a whole-cell patch clamp, and the evoked current was measured. Application of 0.1 mM IP3 evoked a prolonged, inward current (52 of 98 neurons) with an average peak amplitude of 89.9 +/- 10.9 pA. The reversal potential of the response induced by IP3 was estimated to be -32.3 +/- 1.5 mV (6 neurons). Bathing the neurons in 10 microM ruthenium red solution greatly reduced the IP3 evoked inward current to 18.0 +/- 4.6 pA (5 neurons). This is the first study to demonstrate that the membranes of the turtle vomeronasal neurons carry IP3-activated conductance.

Animals↗
PubMed1994

Forskolin enhanced off-response in the turtle olfactory system.

Olfactory responses appear not only at the onset of odor stimulation, but also at the termination of the stimulation. It is widely considered that the cAMP-pathway is involved in the generation of odor responses. We examined how cAMP affects the generation of off-responses. To explore the role of the cAMP-pathway, odorants were applied to the turtle olfactory epithelium after forskolin at high concentrations which saturated the olfactory response to forskolin. Various odorants induced off-responses after 50 microM forskolin, indicating that off-responses are not induced via the cAMP-dependent pathway. However, the magnitude of the off-response after forskolin varied from 100 to 1400% of those of off-responses in its absence, indicating that forskolin greatly enhanced the off-responses to some odorants. The off-response after 0.1 mM citralva was also enhanced by 3 mM 8-(4-chlorophenylthio)-adenosine 3',5'-cyclic monophosphate (cpt-cAMP). These results suggested that cAMP modulates off-responses in the turtle olfactory system.

1-Methyl-3-isobutylxanthine↗
PubMed1994

A large contribution of a cyclic AMP-independent pathway to turtle olfactory transduction.

Although multiple pathways are involved in the olfactory transduction mechanism, cAMP-dependent pathway has been considered to contribute mainly to the transduction. We examined the degree of contribution of cAMP-independent pathway to the turtle olfactory response by recording inward currents from isolated cells, nerve impulses from cilia and olfactory bulbar responses. The results obtained by the three recordings were essentially consistent with each other, but detail studies were carried out by recording the bulbar response to obtain quantitative data. Application of an odorant cocktail to the isolated olfactory neuron after injection of 1 mM cAMP from the patch pipette elicited a large inward current. Mean amplitude of inward currents evoked by the cocktail with 1 mM cAMP in the patch pipette was similar to that without cAMP in the pipette. Application of the cocktail after the response to 50 microM forskolin was adapted also induced a large inward current. Application of the odorant cocktail to the olfactory epithelium, after the response to 50 microM forskolin was adapted, brought about an appreciable increase in the impulse frequency. The bulbar response to forskolin alone reached a saturation level around 10 microM. After the response to 50 microM forskolin was adapted, 11 species of odorants were applied to the olfactory epithelium. The magnitudes of responses to the odorants after forskolin were 45-80% of those of the control responses. There was no essential difference in the degree of the suppression by forskolin between cAMP- and IP3-producing odorants classified in the rat, suggesting that certain part of the forskolin-suppressive component was brought about by nonspecific action of forskolin. Application of a membrane permeant cAMP analogue, cpt-cAMP elicited a large response, and 0.1 mM citralva after 3 mM cpt-cAMP elicited 51% of the control response which was close to the response to citralva after 50 microM forskolin. A membrane permeant cGMP analogue, db-cGMP elicited a small response and the response to 0.1 mM citralva was unaffected by db-cGMP. It was concluded that cAMP-independent (probably IP3-independent) pathway greatly contributes to the turtle olfactory transduction.

1-Methyl-3-isobutylxanthine↗
PubMed1992

Quantitative analysis on odor intensity and quality of optical isomers in turtle olfactory system.

No systematic electrophysiological study on differences in odor intensity and quality between optical isomers has been carried out. In the present study, we measured the turtle olfactory bulbar responses to six pairs of highly pure optical isomers and compared the differences in odor intensity and quality between the optical isomers. The results obtained indicated that with all odorants tested, there was no difference in odor threshold and intensity in the whole concentration range examined between optical isomers. The difference in odor quality of optical isomers was evaluated by a quantitative cross-adaptation method in which odorant concentration was varied. The degree of cross adaptation between optical isomers greatly varied with species of odorants. The rank order of the magnitude of the differences in odor quality between optical isomers was carvone greater than beta-citronellol greater than menthol greater than hydroxycitronellal greater than citronellal greater than limonene.

Adaptation, Physiological↗
PubMed1991

Liposomes having high sensitivity to odorants.

The conditions to increase the sensitivities of liposomes to odorants were examined. The results obtained are as follows. (1) The minimum concentration of amyl acetate to induce the membrane potential changes (threshold) in phosphatidylcholine (PC) liposomes was about 10(-4) M and addition of 10 or 20% phosphatidylserine (PS) lowered the threshold to about 10(-9) M, which was lower than the thresholds for amyl acetate in the turtle and frog olfactory systems. (2) Similar to amyl acetate, addition of PS to PC greatly lowered the threshold for beta-ionone. On the other hand, addition of PS to PC in certain ratio increased the threshold for citral, suggesting that addition of PS to PC does not always increase the responses to all odorants. (3) The membrane fluidity change of the liposomes in response to odorants occurred at similar concentration region where the membrane potential changes occurred. The presence of CaCl2 in external solution much greatly increased both the magnitude of the membrane potential changes and the membrane fluidity changes of the PC-PS liposomes in response to amyl acetate than the presence of NaCl and MgCl2. These results suggest that the membrane fluidity change is related to generation of the membrane potential change. (4) It was estimated that adsorption of less than a few molecules of amyl acetate on single liposome elicits detectable changes in the membrane potential and the membrane fluidity.

Benzothiazoles↗
PubMed1991

Differential ion dependence of frog olfactory responses to various odorants.

1. Dependence of the fron olfactory bulbar responses on NaCl concentration greatly varied from odorant to odorant. The responses to odorants such as 1-carvone and isoamyl acetate were essentially unchanged by removal of NaCl, while those to odorant such as citral and beta-ionone were greatly decreased by removal of NaCl. 2. The NaCl requirement for the responses to certain odorants was greatly decreased by an increase in pH or temperature of the stimulating solution. 3. It was concluded that changes in ion permeability at the apical membranes of olfactory cells including olfactory ciliary membranes are not involved in generation of the in vivo olfactory responses to certain odorants.

Animals↗
PubMed1990

Water response of frog olfactory system is induced by a decrease in osmotic pressure.

The frog olfactory response to deionized water (water response) was recorded from the olfactory bulb. The water response was suppressed by both electrolytes and non-electrolytes as a function of osmolarity, while the water response in taste cells was not suppressed by non-electrolytes. It was concluded that a decrease in osmotic pressure induced by application of deionized water is the origin of the water response in the frog olfactory system.

Action Potentials↗
PubMed1990

Membrane fluidity changes of liposomes in response to various odorants. Complexity of membrane composition and variety of adsorption sites for odorants.

Three kinds of liposomes prepared from phosphatidylcholine (PC), azolectin, and azolectin-containing membrane proteins of the canine erythrocytes were used as models for olfactory cells. To explore properties of the adsorption sites of odorants, membrane fluidity changes in response to various odorants were measured with various fluorescence dyes which monitor the fluidity at different depths and different regions of the membranes. (a) Application of various odorants changed the membrane fluidity of azolectin liposomes. The patterns of membrane fluidity changes in response to odorants having a similar odor were similar to each other and those in response to odorants having different odors were different from each other. These results suggested that odorants having a similar odor are adsorbed on a similar site and odorants having different odors are adsorbed on different sites. (b) Such variation of the pattern was not seen in liposomes of a simple composition (PC liposome). (c) In the proteoliposomes whose composition was more complex than that of azolectin liposomes, the patterns of membrane fluidity changes varied among odorants having a similar odor. It was concluded that liposomes of complex membrane composition have the variety of adsorption sites for odorants.

Acyclic Monoterpenes↗
PubMed1989

Mechanism of the water response in frog gustation: possible significance of surface potential.

The frog taste response to deionized water (water response) after adaptation of the tongue to salts was recorded from the glossopharyngeal nerve under various conditions. It was found that the frog water response exhibits different behavior from the carp water response examined in a previous paper13. (a) The frog water response did not decline during stimulation and lasted for at least 3 min, while the carp water response declined within 10 s after stimulation to a spontaneous level. (b) The frog water response was practically independent of species and concentrations of salts in adapting solutions when the tongue was adapted to salts of monovalent cations, while the carp water response was highly dependent of salt concentration in adapting solution. (c) The water response was increased with an increase of CaCl2 concentration in adapting solution, while it was decreased with an increase of MgCl2 concentration. (d) The water response was suppressed by the presence of electrolytes in stimulating solution: the data obtained with different species of salts were described by a single curve as a function of the ionic strength. (e) The mechanism of the frog water response together with the carp water response was explained in terms of the surface potential.

Action Potentials↗
PubMed1988

Large olfactory responses of the carp after complete removal of olfactory cilia.

To study the role of olfactory cilia on olfactory reception, the carp olfactory cilia were removed by modified "ethanol-calcium shock" and the bulbar responses were recorded before and after deciliation. Large olfactory responses to various amino acids were observed after complete deciliation. The relation between magnitude of olfactory response and alanine concentration before and after deciliation was essentially unchanged. The present results suggests that the olfactory cilia may not be necessary for receptor neuron function in the carp.

Animals↗
PubMed1987

Cell suspensions from porcine olfactory mucosa. Changes in membrane potential and membrane fluidity in response to various odorants.

A suspension of olfactory epithelial cells was prepared from porcine olfactory mucosa and the physiological functions of the suspension were examined. The membrane potential of the cell suspension, which was monitored by measuring the fluorescence changes of rhodamine 6G, was depolarized by an increase in the K+ concentration in the external medium. Various odorants depolarized the cell suspension in a dose-dependent fashion. The magnitude of depolarization by odorants was either unchanged or slightly increased by a reduction of the concentration of Na+, Ca2+, and Cl- in the external medium, which suggests that changes in the permeabilities of specific ions are not involved in depolarization by odorants. The application of various odorants to the cell suspension induced changes in the membrane fluidity at different sites of the membrane that were monitored with various fluorescent dyes [8-anilino-1-naphthalene sulfonate, n-(9-anthroyloxy) stearic acids, 12-(9-anthroyloxy) oleic acid, and (1,6-diphenyl-1,3,5-hexatriene)], which suggests that the odorants having different odors are adsorbed on different sites in the membrane. On the basis of these results, a possible mechanism of odor discrimination is discussed.

Animals↗
PubMed1986

Contribution of electrostatic and hydrophobic interactions of bitter substances with taste receptor membranes to generation of receptor potentials.

The effects of changed ionic environments on the frog taste nerve responses to the bitter substances were examined. The responses to quinine and strychnine carrying a positive charge were suppressed by an increase in ionic strength of stimulating solutions. It was concluded that electrostatic interaction of these positive bitter substances with the receptor membranes greatly contributes to the adsorption of the substances on the membranes and that this interaction was suppressed by an increase in ionic strength. The responses to neutral bitter substances (caffeine and theophylline) were unchanged by an increase in salt concentration. The zeta potential of the mouse neuroblastoma (N-18 clone), which was depolarized by various bitter substances similarly to a taste cell, was measured in the presence of the bitter substances. The zeta potential was a little changed by quinine and practically unchanged by strychnine, caffeine and theophylline. The membrane fluidity of the N-18 cell monitored with 2-(9-anthroyloxy)stearic acid was changed in response to the bitter substances, while the fluidity monitored with 12-(9-anthroyloxy)stearic acid or 1,6-diphenyl-1,3,5-hexatriene was unchanged. This suggested that the bitter substances are adsorbed on the hydrophobic region near the surface and induce a conformational change at the region. The depolarization by the bitter substances seems to stem from changes in the "boundary potential" at the region near the surface within the membrane interior.

Adsorption↗
PubMed1985

Evidence for non-receptor odor discrimination using neuroblastoma cells as a model for olfactory cells.

The mouse neuroblastoma cell (N-18 clone), which is independent of an olfactory cell, was depolarized by 20 odorants examined, suggesting that specific proteins are not required for reception of odorants. The mechanism of non-receptor-mediated odor discrimination was examined using the N-18 cell. Changes in the membrane fluidity of the cell induced by adsorption of odorants were measured with various fluorescence probes, which monitor the fluidity at the different depth and in the different phase of the membrane. The profiles of the membrane fluidity changes monitored with these dyes were different from one species of odorants to another, suggesting that odorants having different odors are adsorbed at different sites in the membranes. The alteration of the lipid composition of the cell membrane brought about by exogenous application of stearic acid and cholesterol led to modification of the responses (magnitude of depolarization) to various odorants. The extent and direction (increase or decrease) of changes in the responses greatly varied among species of odorants. The following mechanism on odor discrimination was proposed. A membrane composition of each olfactory cell is postulated to be different from cell to cell. Different combinations of lipids and proteins in the membranes provide different adsorption sites for odorants. Relative amounts of the membrane potential changes in many olfactory cells in response to an odorant are characteristic of the species of the odorant. The response profiles at the cell level determine the quality of the odor.

Animals↗
PubMed1985

Neuroblastoma cell as a model for a taste cell: mechanism of depolarization in response to various bitter substances.

The mouse neuroblastoma cell (N-18 clone) was used as a model for a taste cell. The N-18 cell was found to be reversibly depolarized by various bitter substances. The minimum concentrations of bitter substances which induced depolarization (threshold concentration) varied greatly with the type of the substance. There was a good correlation between the threshold concentrations for various bitter substances in the N-18 cell and those in the human taste responses. The input membrane resistance was little changed during the depolarization induced by the bitter substances. Replacement of Na+ and Cl- with impermeable ions had practically no effect on the depolarization response to the bitter substances and reduction of calcium concentration from 1.8 to 0.2 mM led to a slight increase in the responses. It was suggested that the depolarization of the N-18 cell by bitter substances mainly stems from changes in the phase-boundary potential at the outer surface of the cell.

Animals↗
PubMed1984

Neuroblastoma cell as model for olfactory cell: mechanism of depolarization in response to various odorants.

The mouse neuroblastoma cell (N-18 clone) was used as a model for an olfactory cell. The N-18 cell was found to be depolarized reversibly by various species of odorants. The minimum concentrations of odorants which induced depolarization (threshold concentration) varied greatly with the species of odorants. There was a good correlation between the order of the threshold concentrations for various odorants in the N-18 cell and that in the frog olfactory responses. Replacement of Na+ and Cl- with impermeable ions or reduction of calcium concentration from 1.8 mM to 0.1 mM had practically no effect on the magnitude of the depolarization response to odorants. The input membrane resistance was little changed during the depolarization induced by various odorants. No reversal potential was observed when the cell was depolarized by n-amyl acetate or vanillin. It is suggested that the depolarization of N-18 cell by odorants is induced by changes in the phase-boundary potential at the outer surface of the cell.

Animals↗