Spatial organization of calcium dynamics in growth cones of sensory neurones.
The concentration of calcium ions in the cytosol ([Ca2+]i) has a dominant influence on neuronal development. A [Ca2+]i rise can, depending on the amplitude and location, promote outgrowth or dramatically inhibit it. We have used the fluorescent calcium indicators Fura-2 and Fura-2 dextran to measure [Ca2+]i dynamics in sensory neurones from the adult rat. [Ca2+]i was low and uniform in advancing growth cones, even during specific behaviours such as protrusion, filling and consolidation. A brief train of action potentials caused [Ca2+]i to rise at the extreme leading edge of the growth cone. [Ca2+]i changes in more proximal regions of the growth cone were much smaller. This spatially organized [Ca2+]i change, which may result from a concentration of calcium channels at the growth cone leading edge, is likely to function in spontaneously active regenerating axons in vivo to specifically activate calcium-dependent processes at the growth cone tip.
Amato
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Department of Physiology, University College London, London, UK.
Al-Mohanna
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FA
Bolsover
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D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D004594:Electrophysiology; D005260:Female; D008297:Male; D009416:Nerve Regeneration; D016501:Neurites / Q000502:physiology; D009475:Neurons, Afferent / Q000378:metabolism / Q000502:physiology*; D009994:Osmolar Concentration; D051381:Rats; D013997:Time Factors; D014018:Tissue Distribution
D015220:Calcium Channels; D002118:Calcium