Search PubMed⌕ Search

Biomedical subjects

C Yamamoto

Publications and source records attributed to C Yamamoto.

At least 271 records · Page 15Linked to original sources
PubMed1980

Electrical activity recorded from thin sections of the bed nucleus of the stria terminalis, and the effects of neurotensin.

Effects of neurotensin on neurons in the bed nucleus of the stria terminalis (BST) were studied in vitro in thin brain sections of the guinea pig. Electrical stimulation to the stria terminalis (ST) elicited a negative field potential in the BST. The field potential was markedly suppressed in the medium containing Ca2+ at a low concentration of Mg2+ at a high concentration. BST neurons discharged in response to ST stimulation. Some of them also fired spontaneously. Neurotensin excited about two-thirds of BST neurons at concentrations of 0.35-35 nM. This excitation was not blocked when synaptic transmission was blocked in a medium containing Ca2+ in a low concentration and Mg2+ in a high concentration. These observations suggest that neurotensin is an excitatory transmitter or modulator in the amygdalo-BST projection.

Amygdala↗
PubMed1980

Potentiation of excitatory postsynaptic potentials during and after repetitive stimulation in thin hippocampal sections.

Excitatory postsynaptic potentials (EPSPs) elicited by mossy fiber stimulation were recorded intracellularly from neurons in the CA3 region in thin hippocampal sections in vitro and potentiation of the EPSPs was examined during and after repetitive stimulation. Inhibitory postsynaptic potentials (IPSPs) and seizure discharges were blocked by bicuculline and high concentrations of Mg2+. When two shocks were applied at short intervals, the second EPSP was markedly potentiated. This potentiation declined exponentially with a time-constant of about 180 ms and was unaffected by changes in ambient temperature. The amount of potentiation during a pulse train was explained by summation of potentiation by individual pulses. Post tetanic potentiation lasted longer in media containing Ca2+ at higher concentrations and Mg2+ at lower concentrations. At high Ca2+ concentrations, tetanic stimulation induced long-term potentiation which was occasionally preceded by a long-lasting suppression. Tetanus to a bundle of mossy fibers potentiated EPSPs elicited by stimulation of a separate bundle of mossy fibers (heterosynaptic potentiation) but did not augment EPSPs elicited by fimbrial stimulation.

Animals↗
PubMed1980

Inhibition of dopamine-beta-hydroxylase, A copper enzyme, by bleomycin.

Bleomycin was found to be one of the most potent inhibitors of dopamine-beta-hydroxylase. Bleomycin-A2 at 8 X 10(-8) M inhibited the enzyme activity by 50%. Kinetic studies showed that the inhibition by bleomycin-A2 was of the competitive type with both the substrate and the cofactor, ascorbate, and was not affected by fumarate, a stimulator for the enzyme. The inhibition mechanism is possibly due to chelating action of bleomycin toward the copper atom at the active site of the enzyme together with some other kinds of binding, for the addition of the cupric ions or extensive dialysis completely reversed the inhibition and bleomycin Cu(II)-complex did not inhibit the enzyme.

Adrenal Glands↗
PubMed1980

[First marriage tables for Japanese males and females, 1975].

The authors present net nuptiality tables for Japanese males and females in 1975. Data are from official registers and the 1975 census. "According to the tables, 87.43 percent of newly born males and 91.21 percent of newly born females may expect to marry during their whole life." (SUMMARY IN ENG)

Asia↗
PubMed1979

Dendritic spikes in Purkinje cells of the guinea pig cerebellum studied in vitro.

Extracellular spikes were recorded simultaneously from dendrites and somata of Purkinje cells in thin cerebellar sections. Spontaneously occurring dendritic spikes were biphasic with the initial phase positive. Triphasic dendritic spikes with a large negative phase appeared during electrophoretic application of glutamate. In media containing procaine, tetrodotoxin, or high concentrations of KCl, negative dendritic spikes occurred whereas soma spikes were abolished. The negative dendritic spikes were suppressed by CoCl2 or MnCl2. Electrical stimulation elicited climbing fibre responses in somata and large negative waves in dendrites. Spikes of dendritic origin were different from those reflecting electrotonic spread of soma spikes. The relation between soma spikes and active dendritic spikes is discussed.

Animals↗
PubMed1977

Inhibition and excitation induced by glutamic acid on cerebellar interneurons.

Thin sections of guinea pig cerebellum were incubated in an artificial medium and responses of neurons in the granular layer to glutamic acid were studied. About half of these neurons were inhibited by glutamate administered electrophoretically (GI cells) and others were excited (GE cells). The GI cells were also inhibited in a medium containing glutamate. Gamma-amino butyric acid inhibited the GI as well as the GE cells. The inhibition in the GI cells induced by glutamate was not susceptible to picrotoxin or strychnine medication, and was not blocked in a CI-free medium or in a medium containing CA2+ in low concentrations and Mg2+ in high concentrations. Some GI cells showed high-amplitude spikes which were recordable at distances of tens of micrometer from the cell. These observations indicate that at least some of the GI cells were large Golgi cells and that the inhibition induced by glutamate in the GI cells was not mediated by inhibitory interneurons.

Action Potentials↗