Changes in intracellular pH of mouse hippocampal slices responding to hypoxia and/or glucose depletion.

Effects of hypoxia and/or glucose depletion on apparent intracellular pH, (pHi)app, were studied in hippocampal slices of mouse brain using the fluorescence pH indicator BCECF (2',7'-bis(carboxyethyl)carboxyfluorescein). In the presence of glucose (11 mM), (pHi)app of the CA1 pyramidal cell layer decreased with hypoxia but rapidly recovered with reoxygenation. The response in (pHi)app to hypoxia was consistent with changes in lactate content. By superfusion with a hypoxic and glucose-devoid solution, (pHi)app decreased in the first 5 min, but then increased in two phases: during a 5- to 7-min period and again during the latter period of superfusion. BCECF fluorescence rapidly diminished in this latter period. These changes in (pHi)app could not be explained only by the lactate content in the slices. Some other mechanisms may also regulate the (pHi)app in the slices during and after hypoxia and glucose depletion.