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  • 1
    Electronic Resource
    Electronic Resource
    Synaptic responses to mechanical stimulation in calyceal and bouton type vestibular afferents studied in an isolated preparation of semicircular canal ampullae of chicken (1990)
    Springer
    Experimental brain research 80 (1990), S. 475-488 
    Details
    ISSN: 1432-1106
    Keywords: Vestibular afferents ; Synaptic responses ; Mechanical stimulation ; Isolated semicircular canal ampullae ; Chicken
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Relationships between the response patterns of semicircular canal afferents to mechanical stimulation and the morphologies of their peripheral endings were investigated in an isolated preparation of the anterior semicircular canal ampulla of chicken, using a combination of electrical recording with intracellular injections of Lucifer Yellow CH. The hair bundle mechanical stimulus was applied in a diffuse manner by a glass rod vibrating in the nearby bathing medium. Two types of spike discharge patterns and postsynaptic potentials were recorded. One type was found exclusively in the bouton type afferent and demonstrated a phasic increase of firing frequency and transient depolarizing postsynaptic potentials at the beginning of mechanical stimulation. These synaptic potentials were also observed spontaneously and their amplitudes were increased by membrane hyperpolarization. The other type was found exclusively in afferents with calyceal endings and showed a tonic increase of spiking frequency and depolarizing DC postsynaptic potentials with superimposing AC responses at the frequency of the mechanical stimulation. Amplitudes of postsynaptic potentials were increased by hyperpolarization. Hair cells generated depolarizing DC transduction potentials superimposed with AC potentials at frequency of the mechanical stimulation. The spontaneous spike discharging patterns of afferent nerve fibres were classified either as a regular type (CV 〈 0.10) or as an irregular type (CV 〉 0.25) on the basis of coefficient of variation (CV) of interspike intervals. The spontaneous firing rate of regular units was higher than that of irregular units. Several membrane characteristics are different between these two types of afferent fibers; irregular units had short membrane time constants and fast spikes associated with clear spike-afterhyperpolarization. These features fit with the fact that irregular units tend to have phasic responses to mechanical stimulation while regular units typically have tonic responses. Irregular units had bouton endings with an average axonal diameter thicker than the regular units which had calix endings.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227989
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Acetylcholine dose-response relation and the effect of cesium ions in the rat adrenal chromaffin cell under voltage clamp (1987)
    Springer
    Pflügers Archiv 408 (1987), S. 401-407 
    Details
    ISSN: 1432-2013
    Keywords: ACh-induced current ; Adrenal chromaffin cell ; ACh dose-response curve ; Channel block by CS ions ; Whole cell voltage clamp
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Acetylcholine(ACh)-induced inward current was examined in the rat adrenal chromaffin cell in culture. Cells were voltage clamped with one electrode using the giga-seal technique. The ACh dose-response relationship was determined by applying various concentrations of ACh with the “puffer” method. Although there were several technical difficulties, we found tentative figures as 135 to 480 μM for the dissociation constant and 1.2 to 1.4 for the Hill coefficient. External Cs ions had a depressing effect on the ACh reponse. Cs ions may slowly block ACh receptor channels from outside at the resting state. The ACh response in normal saline recorded with the Cs-filled electrode reversed the polarity at −7.1 mV. When the amplitude of ACh-induced current was plotted against holding membrane potential the curve showed strong rectification at the region more negative than the reversal potential. Between +10 and +30 mV there was a region of a negative slope. We discussed possible mechanisms for this characteristic I–V curve.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00581136
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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