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  • 1
    Electronic Resource
    Electronic Resource
    The effects of Al on the calcium currents inHelix neurons (1994)
    Springer
    Cellular and molecular neurobiology 14 (1994), S. 809-817 
    Details
    ISSN: 1573-6830
    Keywords: voltage clamp ; molluscan neuron ; Al treatment ; Ca currents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. The effects of aluminium (Al) on calcium (Ca) currents were investigated by using the conventional two-electrode voltage clamp technique inHelix pomatia neurons. The peak amplitude, kinetics, and voltage dependence of activation and inactivation of the Ca currents were studied in the presence of 10−5−10−3 M AlCl3, at pH 6. 2. Al prolonged the rising phase of the Ca currents and therefore increased the time to peak at each command voltage step used. 3. There was no significant influence of Al on the peak amplitude of the Ca currents, but the voltage dependence of the time to peak, activation, and inactivation of the Ca currents shifted to more positive potentials as a consequence of Al treatment. 4. The leak currents were not influenced by Al up to 1 mM, which was the maximal dose applied. 5. The results support the suggestion that Al may modify the Ca homeostasis and that it exerts a neurotoxic effect, at least in part, by modulation of the Ca current of the neuronal membrane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02088686
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  • 2
    Electronic Resource
    Electronic Resource
    The organization of serotonin-, dopamine-, and FMRFamide- containing neuronal elements and their possible role in the regulation of spontaneous contraction of the gastrointestinal tract in the snail Helix pomatia (1998)
    Springer
    Journal of neurocytology 27 (1998), S. 761-775 
    Details
    ISSN: 1573-7381
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Summary The distribution of serotonin-, tyrosine hydroxylase-, and FMRFamide-immunoreactive neuronal elements, as well as the concentrations of serotonin and dopamine in the different parts of the gastrointestinal tract, were studied in the snail Helix pomatia. The sensitivity of the spontaneous contractions of the alimentary tract to serotonin, dopamine, and FMRFamide was also tested. Serotonin-, tyrosine hydroxylase-, and FMRFamide-immunoreactive elements could be demonstrated in each part of the gastrointestinal tract, but they showed different innervation patterns. Serotonin- and tyrosine hydroxylase-immunoreactive elements were dominant in the submucosal layer, whereas FMRFamide-immunoreactive elements were dominant in both the mucosal and submucosal layers. Tyrosine hydroxylase-immunoreactive elements were confined to the longitudinal muscle trabeculae of submucosa, whereas serotonin-immunoreactive elements were distributed throughout the submucosal layer. No serotonin-immunoreactive cell bodies, but only fibers, could be detected in the gastrointestinal tract, and therefore they represent extrinsic elements. Tyrosine hydroxylase- and FMRFamide-immunoreactive cell bodies represent intrinsic elements of the tract. The occurrence and density of the serotonin- and tyrosine hydroxylase-immunoreactive elements showed significant differences in the different parts of the alimentary tract, in accordance with HPLC assays, which revealed a significant frontocaudal decrease in both the serotonin (from 2.11 to 1.21 pM/mg) and dopamine (from 3.28 to 0.52 pM/mg) contents of the different parts of the alimentary tract. Dopamine at 10-5 M concentration proved to be effective only on the longitudinal muscles by increasing the tone and frequency of contractions, but was ineffective on the circular muscles. Serotonin affected both the longitudinal and circular muscles. Serotonin at 10-5 M concentration decreased the tone and increased the frequency of low-amplitude contractions of the longitudinal muscles of the esophagus and the gizzard but increased both the tone and frequency of the crop. Serotonin at 10-9 M concentration slightly decreased the tone and blocked the contractions of the circular muscles in the crop but at 10-5 M concentration induced contractions of the circular muscles in the gizzard. FMRFamide at 10-6 M concentration decreased the tone and was shown to block the contractions of both the longitudinal and circular muscles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006955018882
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  • 3
    Electronic Resource
    Electronic Resource
    Mytilus inhibitory peptides (MIP) in the central and peripheral nervous system of the pulmonate gastropods, Lymnaea stagnalis and Helix pomatia: distribution and physiological actions (2000)
    Springer
    Cell & tissue research 302 (2000), S. 115-134 
    Details
    ISSN: 1432-0878
    Keywords: Neuropeptides Mytilus inhibitory peptides (MIP) Immunocytochemistry Central and peripheral nervous system Invertebrates Lymnaea stagnalis, Helix pomatia (Gastropoda, Mollusca)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The distribution and neuroanatomy of Mytilus inhibitory peptides (MIP)-containing neurons in the central nervous system and their innervation pattern in the peripheral nervous system of the pulmonate snail species, Lymnaea stagnalis and Helix pomatia, have been investigated immunocytochemically, by applying an antibody raised to GSPMFVamide. A significant number of immunoreactive neurons occurs in the central nervous system of both species (Lymnaea: ca 600–700, Helix: ca 400–500), but their distribution is different. In Lymnaea, labeled neurons are found in all central ganglia where a number of large and giant neurons, previously identified physiologically, reveal MIP immunoreactivity. In Helix, most of the immunolabeled neurons are small (12–30 µm) and concentrated in the buccal and cerebral ganglia; the parietal ganglia are free of labeled cells. In both species, the ganglionic neuropils, peripheral nerves, connectives, and commissures are richly supplied with immunolabeled fibers. The MIP-immunoreactive innervation pattern in the heart, intestine, buccal mass and radula, and foot is similar in both species, with labeled axonal bundles and terminal-like arborizations (buccal mass, foot) or a network of varicose fibers (heart, intestine). Intrinsic neurons are not present in these tissues. The application of GSPYFVamide inhibits the spontaneous contractions of the esophageal longitudinal musculature in Helix, indicating the bioactivity of the peptide. An outside-out patch-clamp technique has demonstrated that GSPYFVamide opens the K+ channels in central nerve cells of Helix. Injection of GSPYFVamide into the body cavity inhibits the feeding of starved Helix. A wide modulatory role of MIP at central and peripheral levels is suggested in Lymnaea and Helix, including the participation in intercellular signalling processes and remote neurohormonal-like control effects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410000252
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    Paper (German National Licenses)
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