116 MARTIN G. LARRABEE AXD PAUL HOROWICZ 



potential of the biochemical components of a dead tissue, a tissue that cannot 

 come back? 



Dr. Louis Sokoloff (National Institutes of Health): I wondered whether 

 the EEG picture or the behavior pattern of a comatose human being, reflects 

 the normal brain? Does the presence of electrical activity mean anything? 



Dr. Larrabee: I would like to ask Dr. Abood how long these brains were per- 

 fused without glucose? Also, whether this is an ordinary perfusion or a recircula- 

 tion system? 



Dr. Abood: The brain will survive about two hours and there is a gradual 

 diminution of the electrical activity. It is not perfectly normal during that 

 time and it is a recirculated perfusion. 



Chairman Gerard: Let me add a word here for some clarification. There 

 have been biopsies made on the brain throughout and there is no change in the 

 carbohydrate reserve in the brain. There is no glucose in the fluid going to the 

 brain and there is no loss in the carbohydrate in the brain and it functions not 

 only as tested by the electrical manifestations but as tested also by the reflex 

 activity, which partly meets the point there. The question that Folch-Pi throws 

 out, I think, is a searching and important one. What some of these lines of 

 discussion come down to, it seems to me, is best exemplified in these experi- 

 ments on the phosphorylating capacities of the isolated brain mitochondria 

 that we did a couple of years ago. I will merely remind you this was precipitated 

 by Mcllwain's visit to our laboratory when he tried and failed to get any elec- 

 trical evidence of impedance change in brain slices even though they were 

 giving the biochemical responses to shocks applied to them. 



In the absence of that, our conclusion was that these were not physiological 

 responses and we went off in another direction. We found that isolated brain 

 mitochondria, which we never for a moment thought were giving physiological 

 responses, give exactly the same biochemical changes on being exposed to shocks 

 in the suspension medium. The significant thing about the changes, as finally 

 worked out with the aid of tracer phosphate, was that the decrease in phosphate 

 associated with the electrical pulses, what you might call excitation, was pri- 

 marily a decreased formation rather than an increased breakdown, which upsets 

 the whole energy aspect and throws it into some relationship to excitability. 



But, if there is a basic tie-up between excitation and metabolic change that 

 is essential to or meaningful for the functioning of cells — one would hate to not 

 think so — then certainly, important fragments of that remain intact when you 

 have gotten inside the cell and you have no cell membrane and you are just 

 down to the particulars. 



Is that at all responsive to your question? 



Dr. Folch-Pi: Yes, I think that is the way to look at it. 



Dr. Marshall: I would like to ask for a little more rigorous clarification of 

 the definition or specification of what people mean by electrical stimulation 



