RT Journal Article
SR Electronic
T1 Elevated cytosolic calcium in the growth cone inhibits neurite elongation in neuroblastoma cells: correlation of behavioral states with cytosolic calcium concentration
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 4007
OP 4020
DO 10.1523/JNEUROSCI.09-11-04007.1989
VO 9
IS 11
A1 RA Silver
A1 AG Lamb
A1 SR Bolsover
YR 1989
UL http://www.jneurosci.org/content/9/11/4007.abstract
AB Schubert (1984) and Kater et al. (1988) have suggested that motility and growth at the neuronal growth cone is activated by an increase of cytosolic free calcium concentration ([Ca2+]i) above the levels found in quiescent growth cones. In order to test this model, we have used a digital imaging fluorescence microscope together with injection of the fluorescent indicator dye Fura-2 to measure [Ca2+]i in growth cones of a mammalian sympathetic neuron, the N1E-115 neuroblastoma cell. The behavior of individual growth cones, together with spontaneously varying levels of [Ca2+]i within the growth cone, were monitored for periods of up to several hours. [Ca2+]i in motile, advancing growth cones was low and equal to [Ca2+]i in quiescent growth cones. Higher values of [Ca2+]i were found in motile growth cones that were not advancing, suggesting that a small elevation of [Ca2+]i inhibits neurite extension. A further rise of [Ca2+]i above the level found in motile, nonadvancing growth cones appeared to inhibit motility and cause retraction of the growth cone back towards the cell body. Spatial gradients of [Ca2+]i within the growth cone were small and, where statistically significant, [Ca2+]i was lower by 5–10 nM in motile regions. Our results are incompatible with the model that a rise of [Ca2+]i is responsible for activating quiescent growth cones; however, our results suggest that in active growth cones [Ca2+]i can regulate morphology and behavior.