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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 339 (1989), S. 184-191 
    ISSN: 1432-1912
    Schlagwort(e): Capsaicin ; Calcium currents ; Barium currents ; Sensory neurones ; Voltage clamp
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The action of capsaicin (CAP) on the total Ca2+ current was examined in internally perfused voltage-clamped dorsal root ganglion (DRG) neurones of guinea pigs. CAP changed the total Ca2+ current in about 50% of the investigated DRG neurones (“CAP-sensitive” neurones) in the following way: (I) a transient increase of the current amplitude at potentials between − 35 mV and about – 10 mV was accompanied by a shift of the current-voltage relation towards negative potentials by 5–8 mV; (II) the current inactivation was accelerated at potentials positive to about − 35 mV; and (III) the current activation of Ca2+ currents (time to peak values) was also accelerated. Separated low voltage-activated (T-type) currents at potentials negative to about − 35 mV were either not affected or reduced. It remains undecided whether CAP increases T-type currents in a particular potential range or activates an N-type current. External application of 50 μM Ni2+ blocks the effect of CAP, but does not affect the acceleration of the high voltage-activated (L-type) current inactivation induced by menthol. This appears to exclude a CAP effect on L-type current inactivation. “CAP sensitive” and “CAP insensitive” neurones could be discriminated by their different Ca2+ currents: the former demonstrate both fast and slow inactivating currents while the latter have only L-type currents. The observed changes of fast-inactivating Cat2+ currents may be related to the specific action of CAP on peptidergic sensory neurones.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Archives of toxicology 54 (1983), S. 343-352 
    ISSN: 1432-0738
    Schlagwort(e): Cells cultured ; Neurones ; Neuroglia ; Scanning ; Electromicroscopy ; Electrophysiology
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Rat central nervous system has been cultured up to 6 weeks after complete dissociation. Maturation of different cell types has been followed in the quasi monolayer by phase contrast microscopy. Dorsal root ganglion (DRG) neurones usually differed from central nervous system (CNS) neurones by their spherical shape accompanied by only one or two processes, exact identification of cell types, however, was usually only possible by combining morphology with electrophysiology. Scanning electron-microscopy revealed a more extensive arborization of neurites and a higher number of presumed synaptic structures in cultures after 2 weeks of culturing. Layers of ependymal cells were also found. The different cell types were further identified by determining their membrane properties. Glial cells had higher resting membrane potentials (−56±9.7 mV) than CNS neurones (−49±10.2 mV), while the membrane potential of DRG neurones lay inbetween the two (−53±1.7 mV). The sequence for input resistance was: DRG neurones (30±9.3 MΩ) 〉 CNS neurones (18±10.5 MΩ) 〉 glial cells (9.3±5.2 MΩ). In CNS neurones the input resistance is correlated with the membrane potential, which is not the case for glial cells. Action potentials of DRG neurones exhibited delayed repolarisation increasing the spike duration to three times that of CNS neurones.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 1432-0878
    Schlagwort(e): Fluorescent tracers ; Sensory neurones ; Motoneurones ; Double labelling ; Dichotomizing fibres ; Pigeon
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The projection of peripheral sensory and motor nerves was investigated in the pigeon (Columba livia) by means of retrogradely transported fluorescent dyes. Two combinations of fluorescent tracers were used that could be identified within the same cell when excited by light of 405 nm: 1) Propidium iodide and Bisbenzimide, which label the cytoplasm orange and the nucleus blue, respectively; 2) Fast Blue, which labels the cytoplasm blue, and Nuclear Yellow, which labels the nucleus (especially the nucleolar ring) yellow. The presence of the tracers in a given cell was confirmed microspectrophotometrically. Following injection of the tracers into peripheral nerves, labelled sensory neurones were seen in the dorsal root ganglia and motoneurones of the spinal cord. The peroneal and tibial nerves projected to L2–L5 and L2–L7, respectively, whereas the median and ulnar nerves projected to C12-Th2 and C13-Th1. Double-labelled sensory neurones were observed when both peroneal and tibial, or median and ulnar nerves were injected with different tracers. This indicates that some sensory neurones possess peripheral processes that dichotomize to pass down two different peripheral nerves. Double labelling was never seen in motoneurones, or in sensory neurones after tracer injection into the sciatic and femoral nerves.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    ISSN: 1432-0878
    Schlagwort(e): Pudendal nerve ; Sensory neurones ; Spinal ganglion ; Transganglionic labelling (HRP) ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The morphology and distribution of the sensory neurones of the pudendal nerve within the spinal ganglia of rats were investigated by use of horseradish peroxidase (HRP). The labelling was visualized in diaminobenzidine (DAB) or tetramethyl-benzidine (TMB)-stained sections. Injection of HRP directly into the pudendal nerve labelled perikarya predominantly in the sixth lumbar DRG (L6). Following injection of HRP into the scrotal skin, however, additional cells were labelled in L5 and SI. Labelling was invariably unilateral. Approximately equal numbers of small (〈30 μm) and large neurones (〉40 μm) were labelled following subcutaneous injections although injections into the nerve marked twice as many small cells as large cells. This suggests that, in the rat, most of the small-diameter fibres within the pudendal nerve ascend through L6. Although a cluster of neurones was observed in one experiment, the remaining 25 experiments did not reveal any somatotopic arrangement since the labelled perikarya were distributed evenly throughout the ganglion. Similar numbers of retrogradely labelled neurones (somatopetal transport of the tracer) were observed in both DAB- and TMB-stained sections, although TMB allowed the demonstration of anterograde (somatofugal) HRP transport by terminal labelling in the superficial laminae of the lumbar spinal cord, extending into laminae II–IV.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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