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  • Frog  (3)
  • Fluorescence microscopy  (2)
  • Liver  (1)
  • 1
    Electronic Resource
    Electronic Resource
    The inwardly rectifying potassium current of embryonic chick hepatocytes (1995)
    Springer
    The journal of membrane biology 144 (1995), S. 249-255 
    Details
    ISSN: 1432-1424
    Keywords: Whole cell ; Single channel ; Cesium ; Liver ; Resting potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The single channel and whole-cell properties of an inward, rectifying potassium current in cultured embryonic chick hepatocytes were studied at 20°C. In cell-attached patches, channels open upon membrane hyperpolarization and are present in about 90% of cellattached patches. With 145 mm potassium in the pipette, inward current has a slope conductance of 80 pS. The conductance is not a linear function of the external potassium concentration. Current saturates at high external potassium and has a Michaelis-Menten affinity constant of 275 mm potassium. Substitution of gluconate for chloride in the external solution has no significant effect on conductance, and the reversal potential shifts approximately 18 mV with a change in external potassium from 72.5 to 145 mm indicating potassium selectivity. Channel openings are characterized by multiple brief closures during a burst. The channel is inhibited by external cesium in a concentration-dependent manner. Block is characterized by an increased frequency of transient closures. Whole-cell dialysis with 145 mm CsCl of cells bathed in 145 mm KCl reveals time-independent inward currents that reverse at 0 mV in response to 200 msecvoltage steps. Although voltage ramps evoke currents that are 75% potassium dependent and cesium sensitive, the mean chord conductance (425 pS) indicates that less than five channels are open at any instant. We suggest that the inwardly rectifying potassium channel is partially inactivated in the dialysed hepatocyte.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236838
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Distribution and morphology of amphibian extra-adrenal chromaffin tissue (1975)
    Springer
    Cell & tissue research 160 (1975), S. 371-387 
    Details
    ISSN: 1432-0878
    Keywords: Frog ; Chromaffin ; Classification ; Nerve endings ; Fluorescence microscopy ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. The distribution and morphology of chromaffin cells in the para-aortic region and in the ganglia of the paravertebral sympathetic chain was studied with fluorescence histochemistry and electron microscopy. 2. Four types of chromaffin cell were distinguished largely on the basis of their vesicular content: Type I cells contain large, electron-dense vesicles (600–7000 Å) and are comparable to noradrenaline-containing cells in the adrenal gland, Type II cells contain large, vesicles (600–7000 Å) that are filled with a less electron-dense material than that in Type I cells and are comparable to adrenaline-containing cells in the adrenal gland, Type III cells contain smaller vesicles (1000–3000 Å) that are incompletely filled with an electron-dense material and may represent cells that have been depleted of their catecholamines by stimulation, Type IV cells are clearly different from the other three cell types with respect to the size and appearance of the vesicles (1000–1500 Å), nuclei and rough endoplasmic reticulum and may represent immature sympathetic neurons. 3. Nerve profiles, identified as cholinergic, were found in close apposition with all four cell types. No examples of a close association between processes of chromaffin cells and sympathetic neurons were found.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00222046
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Extra-adrenal chromaffin cells grown in tissue culture (1975)
    Springer
    Cell & tissue research 161 (1975), S. 103-117 
    Details
    ISSN: 1432-0878
    Keywords: Tissue culture ; Chromaffin cells ; Frog ; Classification ; Phase contrast microscopy ; Fluorescence microscopy ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. Extra-adrenal chromaffin cells from adult frogs were grown in tissue culture and their morphology and behaviour observed with both light and electron microscopy. 2. Two types of chromaffin cells were distinguished: Type A cells contain large, electron dense vesicles (2000–6000 Å) and are equated to Type I chromaffin cells seen in vivo, i.e. they contain noradrenaline; Type B cells contain smaller vesicles (700–2000 Å) which are incompletely filled with an electron dense material and are equated to Type III chromaffin cells seen in vivo, i.e. cells depleted of their catecholamines by stimulation. No cells comparable to Types II and IV cells in vivo were seen. 3. Close associations between the cultured chromaffin cells and sympathetic neurons were observed with the light microscope, but no examples of synaptic structures were seen in the material examined with electron microscopy in this study.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00222117
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Amphibian sympathetic ganglia in tissue culture (1975)
    Springer
    Cell & tissue research 162 (1975), S. 209-233 
    Details
    ISSN: 1432-0878
    Keywords: Sympathetic neurons ; Frog ; Nerve growth factor ; Accessory cells ; Tissue culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. A culture medium has been developed for amphibian sympathetic nervous tissue but it is suggested that the ionic values should be adjusted to correspond to the concentrations of salts in the plasma of particular species. 2. The morphology, monoamine fluorescence, growth and differentiation of sympathetic ganglia of the frog, Limnodynastes dumerili, have been studied in culture. 3. Two types of neuron could be distinguished largely according to size, namely small, 18×20 μm and large, 38×42 μm. The possibility that these represent one type at different stages in development or represent functionally distinct neurons is discussed. 4. The sympathetic neurons are extremely sensitive to nerve growth factor (NGF) which caused an increase in the size of the cell bodies, the number of nerve fibres regenerating, the rate of axonal growth and synthesis of catecholamines. 5. Various other cell types appearing in the cultures have been described, including chromaffin, satellite, Schwann, multipolar and epithelial cells as well as fibroblasts, melanocytes and macrophages. The epithelial cells show slow contractions and changes in shape.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00209208
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    Paper (German National Licenses)
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