Sensitivity of Intracellular Calcium-Binding Sites for Exo- and Endocytosis of Synaptic Vesicles to Sr, Ba, and Mg Ions

Experiments on frog cutaneous-thoracic muscle preparations using electrophysiological (intra- and extracellular recording of postsynaptic signals) and optical (confocal microscopy with the fluorescent endocytic stain FM 1-43) methods were performed to study neurotransmitter secretion and the process...

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Bibliographic Details
Published in:Neuroscience and behavioral physiology 2010-05, Vol.40 (4), p.389-396
Main Authors: Zefirov, A. L., Grigor’ev, P. N.
Format: Article
Language:English
Subjects:
Animals
Anura
Barium - metabolism
Behavioral Sciences
Binding Sites
Biomedical and Life Sciences
Biomedicine
Calcium - metabolism
Endocytosis
Exocytosis
Experiments
Ion Transport
Magnesium - metabolism
Metals
Muscle, Skeletal - physiology
Neurobiology
Neurosciences
Neurotransmitter Agents - secretion
Potassium
Rana ridibunda
Strontium - metabolism
Synaptic Transmission - physiology
Synaptic Vesicles - physiology
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Summary:Experiments on frog cutaneous-thoracic muscle preparations using electrophysiological (intra- and extracellular recording of postsynaptic signals) and optical (confocal microscopy with the fluorescent endocytic stain FM 1-43) methods were performed to study neurotransmitter secretion and the processes of exo- and endocytosis of synaptic vesicles in motor nerve endings on substitution of extracellular Ca ions with other alkaline earth metals (Sr, Ba, or Mg). Massive asynchronous exocytosis was induced by highpotassium solution, while synchronous exocytosis was induced by prolonged high-frequency stimulation of the motor nerve. The calcium-binding site for asynchronous exocytosis was found to be sensitive to Sr, Ba, and Mg ions, while the site for synchronous exocytosis was only sensitive to Sr ions. During stimulation of both asynchronous and synchronous exocytosis, the calcium-binding site for endocytosis was sensitive to Sr and Ba ions and had the lowest affinity for Sr ions. These experiments led to the conclusion that different intracellular calcium-binding sites exist for the exocytosis and endocytosis of synaptic vesicles and that they have different sensitivities for alkaline earth metals.
ISSN:0097-0549
1573-899X
DOI:10.1007/s11055-010-9269-5