CHAPTER L XX V I 



Central nervous system metabolism in vitro 



P. J. HEALD 



H. McILWAIN 



H. SLOANE- STANLEY 



Institute of Psychiatry {British Postgraduate Medical Federation, 

 University of London), Maudsley Hospital, London, England 



CHAPTER CONTENTS 



Techniques 



Preparation of Tissue 

 Metabolic Conditions 



Metabolic Response to Electrical Excitation 

 Metabolic Studies in Brief Experimental Periods 

 Analytical Notes 

 Normal Metabolic Characteristics 

 Water and Electrolytes 

 Carbohydrate 

 Amino Acids and Proteins 



Glutamic acid 



Ammonia formation 

 Phosphates 



Metabolism in tissue slices 



Metabolism in disintegrated preparations 



Phosphate synthesis and oxidative phosphorylation 

 Lipids 

 Metabolism Modified by Applied Agents 

 Electrical and Cognate Influences 

 Potassium and Other Ions 

 Metabolic Inhibitors 

 Therapeutic and Toxic Agents 



metabolic cycles or sequences occur; and e) prepara- 

 tions, usually cell-free and fractionated, in which 

 individual enzymes can he examined. 



In these different systems it is usual for the tech- 

 nique of study, and also the problems which can use- 

 fully be studied, to differ considerably. Broadly speak- 

 ing, in systems a and b the metabolic events which 

 can be examined approximate fairly closely those 

 accessible in vivo. At < a major transformation occurs 

 in the control of metabolism, the type of substrate 

 .in essible to tissue enzymes and the functional poten- 

 tialities of the preparation. In systems d and e, only 

 relatively isolated aspects of metabolism are open to 

 stuck; for example, energy-yielding and energy- 

 consuming processes are separated, and the studies 

 tend to have as their objective an analysis or under- 

 standing of events in run rather than their simulation. 



Specific references are often not given to work 

 which has already been documented and appraised 

 (136); the collected papers (43, 97) may also be con- 

 sulted. 



this section covers, in summary fashion, metabolic 

 studies in systems of the following distinct types: a) 

 the intact central nervous system which has been the 

 subject of only a few successful metabolic in vitro 

 studies; b) sections from the central nervous system 

 largely retaining cell structure which have been very 

 extensively studies; c) systems in which cell structure 

 has been destroyed but which nevertheless contain all 

 the material of the whole tissue, unfractionated; d) 

 particulate or other preparations in which organized 



TECHNiqUES 



Preparation 0] Tissue 



A major factor in making satisfactory cell-contain- 

 ing tissue preparations is that materials, which in vivo 

 reach the central nervous system from blood capil- 

 laries, should be adequately replaced by materials 

 arriving either from perfusion fluids or by diffusion 

 from an outer surface of the isolated tissue. In the 



1827 



