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Yamamoto D, Ohishi H, Kozawa M, Inamori Y, Ishida T, Inoue M. Study on conformations--biological activities relationships for podophyllotoxin analogues based on crystal structure of deoxypodophyllotoxin (anthricin). Chem Pharm Bull (Tokyo) 1988; 36:3239-47. [PMID: 3240529 DOI: 10.1248/cpb.36.3239] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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177
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Yamamoto D. Activation of protein kinase C promotes glutamate-mediated transmission at the neuromuscular junction of the mealworm. J Physiol 1988; 400:691-700. [PMID: 2901491 PMCID: PMC1191831 DOI: 10.1113/jphysiol.1988.sp017144] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
1. Actions of protein kinase C activators, 1,2-oleoylacetylglycerol (OAG) and 12-O-tetradecanoylphorbol-13-acetate (TPA), on the glutamate-mediated neuromuscular transmission in the mealworm, Tenebrio molitor, were studied by the microelectrode current-clamp and voltage-clamp techniques. 2. The activators OAG and TPA stimulate the evoked and spontaneous transmitter releases from the presynaptic terminal, as evidenced by an increase in the quantum content estimated by the number of failures of extracellular excitatory postsynaptic potentials (EPSPs), and in the frequency of miniature EPSPs. 3. Both OAG and TPA act on the postsynaptic membrane to enhance responses to the transmitter L-glutamate. Protein kinase C activators increased the apparent maximum of the ionophoretic dose-response curve for glutamate-induced depolarization, without affecting the reversal potential and the voltage-dependent decay rate for the excitatory postsynaptic current (EPSC) under voltage-clamp conditions. 4. The postsynaptic effect of OAG and TPA is distinctly different from that of activators of cyclic nucleotide-dependent protein kinases, such as octopamine, forskolin, CPT-cyclic AMP (8-(4-chlorophenylthio)adenosine 3',5'-cyclic monophosphate), and 8-bromo-cyclic GMP (8-bromoguanosine 3',5'-cyclic monophosphate) which decreased the postsynaptic sensitivity to L-glutamate. 5. I suggest that the responsiveness of the receptor to L-glutamate is under the control of these counteracting enzyme systems in the insect neuromuscular junction.
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178
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Shikimi T, Yamamoto D, Handa M. Pancreatic lysosomal thiol proteinases and inhibitors in acute pancreatitis induced in rats. JOURNAL OF PHARMACOBIO-DYNAMICS 1987; 10:750-7. [PMID: 3155425 DOI: 10.1248/bpb1978.10.750] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
When examining the level of esterolysis and that of cathepsin B or H, a significant positive correlation was found in the rat pancreas with inflammation induced by a closed duodenal loop, whereas there was a significant negative correlation between the activity of cathepsin B or H and that of its endogenous inhibitors. The levels of endogenous inhibitors of cathepsins B and H in rats with a pancreatitis were lower than in the sham-treated group. The endogenous inhibitors of cathepsins B and H were destroyed by incubation with the supernatant fraction obtained from the inflamed pancreas. These observations indicate that the activities of pancreatic cathepsins B and H are closely related to the severity of acute pancreatitis and that lesser levels of thiol proteinase inhibitors in the pancreatitis group than in the sham-treated group are due to destruction of the inhibitors by the enhanced protease activity.
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179
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Yamamoto D, Suzuki N. Blockage of chloride channels by HEPES buffer. PROCEEDINGS OF THE ROYAL SOCIETY OF LONDON. SERIES B, BIOLOGICAL SCIENCES 1987; 230:93-100. [PMID: 2438701 DOI: 10.1098/rspb.1987.0011] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Chloride channels of neurons of Drosophila are blocked when the cytoplasmic side of the membrane is exposed to the commonly used buffering agents 4-(2-hydroxyethyl)-1-piperazine ethanesulphonic acid (HEPES) and 4-morpholinepropanesulphonic acid (MOPS). In the presence of these compounds, chloride channels appear to function as a complex of multiple protochannels.
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180
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Yamamoto D, Yeh JZ, Narahashi T. Ion permeation and selectivity of squid axon sodium channels modified by tetramethrin. Brain Res 1986; 372:193-7. [PMID: 2423191 DOI: 10.1016/0006-8993(86)91478-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The pyrethroid tetramethrin greatly prolongs the sodium current during step depolarization and the sodium tail current associated with step repolarization of the squid axon membrane. Non-linear current-voltage relationships for the sodium tail current were analyzed to assess the open sodium channel properties which included the permeation of various cations, calcium block and cation selectivity. Tetramethrin had no effect on any of these properties. It was concluded that tetramethrin modifies the sodium channel gating machinery without affecting the pore properties.
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181
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Abstract
The kinetics of strychnine block of single Na channels in bovine chromaffin cells were studied using the gigohm seal, patch-clamp technique, under the condition in which the Na current inactivation had been eliminated by treatment with N-bromoacetamide (NBA). Strychnine, applied to the cytoplasmic face of Na channels at concentrations ranging from 25 to 100 microM, caused repetitive rapid transitions (flickering) between open and blocked states within single openings of Na channels, without affecting the amplitude of the single-channel current. Average currents in the presence of strychnine accompanied 'hooked' tail currents upon repolarization. The histograms for blocked times and the histograms for open times could be fitted with a single-exponential function. The mean open time (to) became shorter as the drug concentration was increased, while the mean blocked time (tb) was concentration independent. The association (blocking) rate constant, k, calculated from the slope of the curve relating the reciprocal mean open time to strychnine concentration was 7.6 X 10(6) M-1 S-1 at -40 mV in a typical experiment. to-1 and tb-1 had opposite voltage dependences: tb-1 became larger as the membrane was hyperpolarized whereas to-1 became smaller. The voltage dependence suggests that a first-order blocking site is located 35% of the way through the membrane electric field from the cytoplasmic surface. An increase in the external Na+ concentration greatly decreased to-1 without affecting tb-1. The voltage dependence of both to-1 and tb-1 did not change when the external Na concentration was changed. It is suggested that the strychnine block of single Na channels is not 'current-dependent'. All of the features of strychnine block of single Na channels are compatible with the sequential model, in which strychnine molecules block open Na channels, and the blocked channels could not close until strychnine molecules had left the blocking site in the channels.
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182
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Yamamoto D, Yeh JZ, Narahashi T. Interactions of permeant cations with sodium channels of squid axon membranes. Biophys J 1985; 48:361-8. [PMID: 2412601 PMCID: PMC1329350 DOI: 10.1016/s0006-3495(85)83792-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
To determine how the permeant cations interact with the sodium channel, the instantaneous current-voltage (I-V) relationship, conductance-ion concentration relationship, and cation selectivity of sodium channels were studied with internally perfused, voltage clamped squid giant axons in the presence of different permeant cations in the external solution. In Na-containing media, the instantaneous I-V curve was almost linear between +60 and -20 mV, but deviated from the linearity in the direction to decrease the current at more negative potentials. The linearity of instantaneous I-V curve extended to more negative potentials with lowering the external Ca concentration. The I-V curve in Li solution was almost the same as that in Na solution. The linearity of the I-V curve improved in NH4 solution exhibiting only saturation at -100 mV with no sign of further decrease in current at more negative potentials. Guanidine and formamidine further linearized the instantaneous I-V curve. The conductance of the sodium channels as measured from the tail current saturated at high concentrations of permeant cations. The apparent dissociation constants determined from the conductance-ion concentration curve at -60 mV were as follows: Na, 378 mM; Li, 247 mM; NH4, 174 mM; guanidine, 111 mM; formamidine, 103 mM. The ratio of the test cation permeability to the sodium permeability as measured from the reversal potentials of tail currents varied with the test cation concentration and/or the membrane potential. These observations are incompatible with the independence principle, and can be explained on the basis of the Eyring's rate theory. It is suggested that the slope of the instantaneous I-V curve is determined by the relative affinity of permeant cations and blocking ions (Ca) for the binding site in the sodium channel. The ionic selectivity of the channel depends on the energy barrier profile of the channel.
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184
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Abstract
The kinetics of 9-aminoacridine (9-AA) block of single Na channels in neuroblastoma N1E-115 cells were studied using the gigohm seal, patch clamp technique, under the condition in which the Na current inactivation had been eliminated by treatment with N-bromoacetamide (NBA). Following NBA treatment, the current flowing through individual Na channels was manifested by square-wave open events lasting from several to tens of milliseconds. When 9-AA was applied to the cytoplasmic face of Na channels at concentrations ranging from 30 to 100 microM, it caused repetitive rapid transitions (flickering) between open and blocked states within single openings of Na channels, without affecting the amplitude of the single channel current. The histograms for the duration of blocked states and the histograms for the duration of open states could be fitted with a single-exponential function. The mean open time (tau o) became shorter as the drug concentration was increased, while the mean blocked time (tau b) was concentration independent. The association (blocking) rate constant, kappa, calculated from the slope of the curve relating the reciprocal mean open time to 9-AA concentration, showed little voltage dependence, the rate constant being on the order of 1 X 10(7) M-1s-1. The dissociation (unblocking) rate constant, l, calculated from the mean blocked time, was strongly voltage dependent, the mean rate constant being 214 s-1 at 0 mV and becoming larger as the membrane being hyperpolarized. The voltage dependence suggests that a first-order blocking site is located at least 63% of the way through the membrane field from the cytoplasmic surface. The equilibrium dissociation constant for 9-AA to block the Na channel, defined by the relation of l/kappa, was calculated to be 21 microM at 0 mV. Both tau -1o and tau -1b had a Q10 of 1.3, which suggests that binding reaction was diffusion controlled. The burst time in the presence of 9-AA, which is the sum of open times and blocked times, was longer than the lifetime of open channels in the absence of drug. All of the features of 9-AA block of single Na channels are compatible with the sequential model in which 9-AA molecules block open Na channels, and the blocked channels could not close until 9-AA molecules had left the blocking site in the channels.
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185
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Yamamoto D, Yeh JZ, Narahashi T. Voltage-dependent calcium block of normal and tetramethrin-modified single sodium channels. Biophys J 1984; 45:337-44. [PMID: 6324913 PMCID: PMC1435307 DOI: 10.1016/s0006-3495(84)84159-4] [Citation(s) in RCA: 136] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The mechanisms by which external Ca ions block sodium channels were studied by a gigaohm seal patch clamp method using membranes excised from N1E-115 neuroblastoma cells. Tetramethrin was used to prolong the open time of single channels so that the current-voltage relationship could be readily determined over a wide range of membrane potentials. Comparable experiments were performed in the absence of tetramethrin. Increasing external Ca ions from 0.18 to 9.0 mM reduced the single channel conductance without causing flickering. From the dose-response relation the dissociation constant for Ca block at 0 mV was estimated to be 32.4 +/- 1.05 mM. The block was intensified by hyperpolarization. The voltage dependence indicates that Ca ions bind to sodium channels at a site located 37 +/- 2% of the electrical distance from the outside. The current increased with increasing external Na concentrations but showed a saturation; the concentration for half-maximal saturation was estimated to be 185 mM at -50 mV and 204 mM at 0 mV. A model consisting of a one-ion pore with four barriers and three wells can account for the observations that deviate from the independence principle, namely, the saturation of current, block by Ca ions, and rectification in current-voltage relationship. The results suggest that the Ca-induced decrease of the macroscopic sodium current results from a reduced single sodium channel conductance.
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186
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Yamamoto D, Quandt FN, Narahashi T. Modification of single sodium channels by the insecticide tetramethrin. Brain Res 1983; 274:344-9. [PMID: 6313121 DOI: 10.1016/0006-8993(83)90716-3] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
(+)-trans-Tetramethrin, a pyrethroid insecticide, markedly prolongs the open time of single sodium channels recorded by the gigaohm-seal voltage clamp technique in a membrane patch excised from the N1E-115 neuroblastoma cell. Single channel conductance is not altered by tetramethrin. The modification by tetramethrin occurs in an all-or-none manner in a population of sodium channels. The observed tetramethrin-induced modification of single sodium channels is compatible with previous sodium current data from axons.
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187
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Yamamoto D, Quandt F, Narahashi T. Interaction of the insecticide tetramethrin with single sodium channels in neuroblastoma Cells. Toxicol Lett 1983. [DOI: 10.1016/0378-4274(83)90287-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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188
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Petitti DB, Yamamoto D, Morgenstern N. Factors associated with actinomyces-like organisms on Papanicolaou smear in users of intrauterine contraceptive devices. Am J Obstet Gynecol 1983; 145:338-41. [PMID: 6824023 DOI: 10.1016/0002-9378(83)90721-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
To determine the factors associated with the presence of actinomyces-like organisms on cervicovaginal Papanicolaou smears in users of the intrauterine contraceptive device (IUD), we carried out a case-control study. Among about 80,000 Papanicolaou smears examined in one year in a large cytology laboratory, actinomyces-like organisms were identified on 107 smears; all but three smears were from IUD users. Compared with IUD users who did not have actinomyces-like organisms on Papanicolaou smears, those with actinomyces-like organisms had used the IUD for more years. An increased risk of actinomyces-like organisms on Papanicolaou smear was not apparent until 7 years of IUD use, however. No significant association of actinomyces-like organisms with the type of IUD was found after controlling for differences in duration of use between users of various IUDs. The percentage of women reporting gynecologic symptoms (vaginal discharge, pelvic pain, abnormal bleeding) also did not differ significantly between IUD users with and without actinomyces-like organisms on Papanicolaou smear (p = 0.5).
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189
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Yamamoto D, Washio H. Voltage-jump analysis of curare action at a glutamate synapse. J Neurophysiol 1983; 49:396-405. [PMID: 6131946 DOI: 10.1152/jn.1983.49.2.396] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
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190
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Yamamoto D, Washio H. Curare has a voltage-dependent blocking action on the glutamate synapse. Nature 1979; 281:372-3. [PMID: 225677 DOI: 10.1038/281372a0] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The skeletal muscle of members of Orthoptera and Diptera receives an innervation which is probably glutaminergic. Recent study of the ventral muscle fibres in the larvae of the beetle, Tenebrio molitor, has revealed that the transmitter action can be mimicked by the iontophoretic application of L-glutamate to the junctional sites at which the extracellular excitatory postsynaptic potentials (e.p.s.ps) could be recorded (D.Y. and H.W., unpublished observation). Contrary to the evidence favouring glutamate as a transmitter of junctional excitation in insects, some investigators have found that curare (+)tubocrarine, TC), a classic acetylcholine (ACh) antagonist, suppresses the neurally evoked muscle potentials in the fly Sacophaga, and Tenebrio. Here, we have analysed the action of curare on the neuromuscular junction of Tenebrio larvae and found that curare blocked the glutaminergic transmission by antagonising the transmitter at the postsynaptic site.
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191
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Yamamoto D, Washio H. Permeation of sodium through calcium channels of an insect muscle membrane. Can J Physiol Pharmacol 1979; 57:220-2. [PMID: 232671 DOI: 10.1139/y79-033] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The contribution of Na ions to the electrically excited response was studied in the muscle fibres of mealworm larvae, Tenebrio molitor, using microelectrode techniques. When Ca ions were omitted from the external solution, no action potential could be elicited. However, addition of Na ions to Ca-free medium rendered the fibre excitable again. The amplitude of these action potentials increased with a slope of about 40 mV for a 10-fold elevation of external Na concentrations. Tetrodotoxin had no effect on the initiation of the spike, and Co ions completely suppressed it. Therefore, it seems likely that a Ca-channel, which is utilized by both Na and Ca ions, is the sole factor responsible for the action potential in the mealworm larval muscle fibre membrane.
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192
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Yamamoto D, Fukami J, Washio H. Ca-electrogenesis in mealworm muscle: A voltage clamp study. ACTA ACUST UNITED AC 1978. [DOI: 10.1007/bf02034701] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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193
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Blumenstein M, Hruby VJ, Yamamoto D, Yang Y. 13C nuclear magnetic resonance studies of the interactions of bovine neurophysins with (1-hemi-(1-13C)cystine)oxytocin and (1-hemi-(1-13C)cystine,8-arginine)vasopressin. FEBS Lett 1977; 81:347-50. [PMID: 923806 DOI: 10.1016/0014-5793(77)80551-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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194
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Furuhata T, Kataba Y, Yamamoto D, Watanabe T, Chiba T. [Clinical evaluation of amoxicillin in surgical field, with speical reference to annal diseases (author's transl)]. THE JAPANESE JOURNAL OF ANTIBIOTICS 1976; 29:711-4. [PMID: 1048200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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