AEROBIC AND ANAEROBIC P32LABELLING OF PHOSPHOLIPIDS AND ADENOSINE PHOSPHATES IN HYPOTONIC HOMOGENATES OF RAT BRAIN

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Abstract
Under aerobic conditions, a suitably 'reinforced' homogenate of rat brain prepared in distilled water was capable of labelling lipid P, ATP, ADP, and AMP from inorganic P32. The labelling was 'uncoupled' by the addition of DNP. The DNP decreased the specific activity of each of the above compounds and decreased the steady-state concentrations of ATP, with an increase in the concentrations of inorganic P, ADP, and AMP. Fluoride increased the specific activity of the lipid P and the steady-state concentration of ATP. Cyanide decreased the specific activity of lipid P and both the specific activity and the steady-state concentration of ATP.Under anaerobic conditions, the labelling of the lipid P and the adenosine phosphates was as good as that observed in the presence of oxygen. The anaerobic labelling of both lipid P and the adenosine phosphates was less sensitive to DNP or cyanide and more sensitive to iodoacetate than the aerobic labelling. In contrast to the aerobic labelling, the anaerobic labelling was inhibited by fluoride.In most instances, changes in the labelling of lipid P corresponded to those observed for the labelling of ATP. An exception was the labelling of lipid P that occurred under aerobic conditions in the presence of fluoride. Here the specific activity of the lipid P was related to the concentration rather than to the specific activity of ATP.