HYPOXIA IN STRIATAL AND CORTICAL-NEURONS - MEMBRANE-POTENTIAL AND CA2+ MEASUREMENTS

SIMULTANEOUS measurements of membrane potential and intracellular Ca2 mere used to study the effects of hypoxia on striatal and cortical ne urones. Striatal neurones responded to hypoxia with a reversible membr ane depolarization coupled with a transient increase in intracellular Ca2+. Thirty minutes of hypoxia caused an irreversible membrane depola rization associated with a massive raise in Ca2+ levels, leading to ce ll death. Conversely, cortical neurones were more resistant to O-2 dep rivation. Hypoxia (4-10 min) induced minimal changes in both membrane potential and Ca2+ signals. Longer periods (20-30 min) caused an initi al membrane hyperpolarization followed by a large but reversible depol arization coupled with a transient increase in Ca2+ signals. These res ults support the hypothesis of a differential sensitivity of central n eurones to hypoxia, suggesting that striatal neurones are more vulnera ble than cortical cells.