CHANGING OF AN ISOLATED NEURON ULTRASTRUCTURE DURING A PROLONGED IMPACT OF MEDIATOR

WE investigated the influence of prolonged excitation or combined exci tation/inhibition on the ultrastructural changes in an isolated stretc h receptor neurone from crayfish abdomen. Excitatory impulse activity was achieved by mechanical stimulation of a neurone for 10 or 120 min and inhibition of the activity was obtained by perfusion with gamma-am inobutyric acid (GABA, 2.5 x 10(-5) M) for the same periods. Changes i n the ultrastructural components were observed following both excitato ry and inhibitory stimulation for 120 min. Neuronal adaptation to exci tatory or inhibitory stimuli after 120 min resulted in the appearance of an increased number of the giant mitochondria. Thus, the number of giant mitochondria may serve as an ultrastructural index of the degree of neuronal adaptation to external stimulation.