Target Cell Contact Modulates Spontaneous Quantal and Non-Quantal Acetylcholine Release by Xenopus Spinal Neurons
Xenopus nerve-muscle cell culture has proved to be an excellent preparation for study of the development of neuronal ion channel and membrane properties (Spitzer, 1976; Spitzer and Lamborghini, 1976; Willard, 1980) and for studies of synaptogenesis. Much is already known about the properties of the synapses formed in culture, and the changes that take place during maturation, particularly post-synaptically. At synapses formed by growing neurites on muscle cells in 1–2 day old cultures, there are quantal miniature endplate potentials (mEPPs) at frequencies ranging from 0.5 — 4 Hz, with skewed amplitude histograms (Kidokoro et al., 1980; Chow and Poo, 1985). It appears that, at the time of initial synaptic contact, there is no postsynaptic specialization at the site of release—the responses are mediated simply by the acetylcholine (ACh) receptors spread diffusely over the muscle cell’s surface. Only after a time course of hours to days, does the sub-synaptic site develop a high concentration of ACh receptors and other specializations (Anderson and Cohen, 1977; Anderson et al., 1977; Weldon and Cohen, 1979; Kidokoro et al., 1980; Cohen and Weldon, 1980; Takahashi et al., 1987; Chow et al., 1987).
KeywordsGrowth Cone Transmitter Release Cell Pair Culture Muscle Cell Muscle Cell Membrane
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- Anderson, M. J., and Cohen, M. W., 1977, Nerve-induced and spontaneous redistribution of acetylcholine receptors on cultured muscle cells, J. Physiol. (Lond.), 268:757.Google Scholar
- Anderson, M. J., Cohen, M. W., and Zorychta, E., 1977, Effects of innervation on the distribution of acetylcholine receptors on cultured muscle cells, J. Physiol. (Lond.), 268:731.Google Scholar
- Chow, I., and Poo, M-m, 1985, Release of acetylcholine from embryonic neurons upon contact with muscle cell, J. Neurosci., 5:1076.Google Scholar
- Chow, I., Young, S. H., Cheng, J., and Grinnell, A. D., 1987, Development of properties of transmitter release during initial stages of synaptogenesis, Abstr. Soc. Neurosci., 13: in press.Google Scholar
- Grinnell, A. D., and Young, S. H., 1987, Non-quantal release of transmitter at developing neuromuscular junctions of Xenopus in culture, Abstr. Soc. Neurosci., 13: in press.Google Scholar
- Katz, B., “The Release of Neural Transmitter Substances,” Liverpool Univ. Press, Liverpool (1969).Google Scholar
- Spitzer, N., 1976, The ionic basis of the resting potential and a slow depolarizing response in Rohon-Beard neurons of Xenopus tadpoles, J. Physiol. (London), 255:105.Google Scholar
- Takahashi, T., Nakajima, Y., Hirosawa, K., and Onodera, K., 1987, Structure and physiology of developing neuromuscular synapses in culture, J. Neurosci., 7:473.Google Scholar
- Tauc, L., 1982, Non-vesicular release of neurotransmitter, Phys. Rev., 62:857.Google Scholar
- Willard, A., 1980, Electrical excitability of outgrowing neurites of embryonic neurones in cultures of dissociated neural plate of Xenopus laevis, J. Physiol., 301:115.Google Scholar
- Young, S. H., and Chow, I., 1987, Quantal release of neurotransmitter is not associated with opening of large channels on the neuronal membrane. Submitted for publication.Google Scholar