CHEMOPOTENTIALS IN GIANT NERVE CELLS 



181 



'f^^/i^/'r/f'f'/i^f'/'/r'i^r/^r^r'A 



Fig. 2. The autoactivity of the three types of functionally differentiated nerve 

 cells. 



A, Autoactivity of the A soma. The frequency is relatively low (0-5-1/sec) 

 in the standard experimental conditions (20°C, O2, sea water). It is fairly con- 

 stant in the absence of synaptic or antidromic stimulation. 



The amplitude of the A soma spike is the highest (peak to peak, up to 100 mV) 

 and its duration among the shortest (about 6-7 msec). 



Br, Autoactivity of the Br soma. Autoactivity by trains of spikes held on slow 

 waves, the period of which is of the order of 25 sec. The duration of each slow 

 wave is here about 10 sec. The mean spike frequency on each wave is about 4/sec. 



B or Gen, Arhythmic autoactivity. In the absence of any applied stimulus, 

 i.p.s.p.'s are periodically appearing in the spontaneously firing B or Gen cells, 

 so giving rise to characteristic arhythmias. 



Scales for all recordings : 50 mV, 250 msec. 



terized by spontaneous arhythmic activity, owing to the intervening hyper- 

 polarizing potentials (see Fig. 2). 



Such functionally differentiated cells display a different behaviour under 

 the effect of metabolites. In the present article we are concerned only with the 

 changes resulting from anoxia and injection of exogenous CO2. 



2. EXCITATION-INHIBITION DURING ANOXIA 



The first effect is the establishment of an anoxic depolarization. The mean 

 anoxic depolarization for the Br and A cells is about 1 mV/min at 20°C. The 

 arhythmic cells show lower rates of depolarization. A mean value for the 

 most characteristic among them is not yet established. 



If the cells are initially inactive, anoxic depolarization results in firing. In 



