INTRACELLULAR ALKALOSIS DURING HYPOXIA IN NEWBORN MOUSE-BRAIN IN THE PRESENCE OF SYSTEMIC ACIDOSIS - A PHOSPHORUS MAGNETIC-RESONANCE SPECTROSCOPIC STUDY

We investigated the in vivo changes in cerebral energy metabolism and pH, in newborn mice noninvasively during 8 h of hypoxia with FiO(2) = 5%, using phosphorus magnetic resonance spectroscopy continuously, The intracellular brain pH (pH(i)) increased from 7.20 +/- 0.03 to 7.36 /- 0.03 (P < 0.05) at 1 h of hypoxia and then decreased gradually. On the other hand, the mixed arterial and venous blood pH decreased gradu ally during hypoxia, reaching a minimum value of 7.16 +/- 0.01 at the end of the hypoxia, There was no significant difference in P-CO2 betwe en control (47.4 +/- 0.8 mm Hg) and 1-h hypoxic (49.0 +/- 1.1 mm Hg) m ice, The blood glucose concentration was significantly increased at 1 h of hypoxia, These results indicate that the alkaline shift in pH(i) during hypoxia was caused neither by systemic alkalosis due to hypocap nia nor hypoglycemia.