ACID-LABILE PHOSPHATE CONTENT OF INCUBATED BRAIN SLICES

During aerobic incubation of brain cortex slices in glucose-containing medium at 38° the pyrophosphate content of the tissue increases rapidly for 15 minutes and then more slowly. The creatine phosphate content increases rapidly during the first 5 minutes and then falls. Anaerobically, the pyrophosphate falls during the first 30 minutes; the creatine phosphate tends to rise initially and then falls to a lower level than that found aerobically. In the absence of glucose and oxygen the levels of both substances fall rapidly to low levels but can be raised again by aerobiosis in the presence of glucose. In the absence of glucose and oxygen in ice-cold medium, or at 38° in the absence of any medium, the levels of pyrophosphate and creatine phosphate are preserved. More inorganic phosphate is produced when slices are incubated than can be accounted for by breakdown of acid-labile phosphate compounds.It is shown that the initial rate of anaerobic glycolysis by slices which have been subjected to various pretreatments is strongly correlated with the pyrophosphate content of the tissue.The failure of slices to concentrate potassium when immersed in sodium-free media is not due to failure to maintain pyrophosphate levels.