Figure 4.

0 Cl⁻ induced epileptiform activity induces acidic transients in neurons. (A) The intracellular pH of a hippocampal CA1 pyramidal neuron transfected with Cl⁻ sensor recorded during an episode of 0 Cl⁻ induced epileptiform activity. Similar to the 0 Mg²⁺ model, the seizure onset (dashed line) is correlated with the start of a decrease in intracellular pH. The pH continues to decrease during the seizure, reaches a minimum around the time of seizure termination, and then recovers to baseline during the post-seizure period. (B) Similar acidic transients were associated with Cl⁻ induced epileptiform activity in neurons expressing the pH reporter deGFP4. (C) The magnitude of intracellular acidic transients was directly proportional to seizure duration. This relationship was not dependent on the pH reporter (P = 0.2721, Analysis of Covariance, Analysis of Covariance). (D) Maximum pH shifts normalized to a 30 s seizure had an average amplitude of 0.16 ± 0.1 pH units. This did not depend on the pH reporter being used (P = 0.4726, t test).