Figure 11. The two tracings show the electrical currents from cultured
hippocampal neurons. The initial , essentially flat lines interrupted by a
few random spikes of current is the quiescent state maintained by kynurenic
acid (5 µM) added to the culture medium.
When the kynurenic acid was washed of the hippocampal neuron the dense black
area results form a fusion of electrical spikes indicating suicidal
electrical activity, which would kill the cell from depletion of ATP.
Addition of the kynurenic acid to the bathing medium terminated the hyper
electrical response of the neuron returning it to an electrically quiescent
state and the tracing is again flat. When the kynurenic acid was washed out
of the bathing medium EPA (20 µM) was
added to the perfusion fluid. The initial great burst of activity was not
prevented, but very soon the electrical activity was reduced so as not to be
suicidal. The lower tracing shows a repetition of the experiment. |
As shown in Figure 11, we first ran a control
in which the kyneurenic acid was washed out causing a burst of electrical
activity. Before this killed the neuron we added back the kynuerenic acid
and the neuron became electrically quiet again. Then we added EPA (15 µM) to
the bathing medium. This did not prevent an initial very short burst of
electrical hyperactivity. Quickly, however, the activity slowed down to a
non-suicidal rate, which persisted until the EPA was extracted from the
neuron with delipidated bovine serum albumin. The suicidal electrical
activity then recommenced and the kynuerenic acid was promptly reapplied. We
were of course surprised, but very pleased, that the EPA effectively
prevented the suicidal activity of the neuron, so we repeated our experiment
with identical results. Unfortunately, we did not succeed to have this
experiment repeated again on a different sample of cultured neurons, as
Professor Furshpan had other interests to pursue.
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