Quantitative analysis of neurofilament protein  accumulation proximal and  distal to the constriction site  after constriction for 2 h in  the presence or absence of  metabolic substrates. Each  column represents the mean  accumulation ratio for the  number of cells indicated and  the error bars represent the  standard deviation about the  mean as described in the legend to Fig. 5. For these experiments, the L-15-based  culture medium was replaced  with a simpler Dulbecco's  PBS-based medium with or  without 0.6% glucose and  0.055% sodium pyruvate  (fed and starved, respectively). The mean proximal  accumulation ratio in the presence of glucose and pyruvate was  lower than for axons constricted for the same period of time in  L-15-based medium (Fig. 5 A) but it was, nevertheless, reduced  significantly when these two substrates were omitted (P = 0.01,  t test).
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