TY - JOUR T1 - Modulation of gap junctional mechanisms during calcium-free induced field burst activity: a possible role for electrotonic coupling in epileptogenesis JF - The Journal of Neuroscience JO - J. Neurosci. SP - 4308 LP - 4317 DO - 10.1523/JNEUROSCI.14-07-04308.1994 VL - 14 IS - 7 AU - JL Perez-Velazquez AU - TA Valiante AU - PL Carlen Y1 - 1994/07/01 UR - http://www.jneurosci.org/content/14/7/4308.abstract N2 - To date, there is little experimental evidence supporting or refuting electrotonic interactions through gap junctions in the generation and/or spread of seizure activity in the mammalian brain. We have studied gap junctional mechanisms in the in vitro calcium-free induced model of epilepsy using electrophysiological and staining techniques in the CA1 area of the hippocampus. Lucifer yellow staining of CA1 pyramidal neurons revealed that dye coupling was increased 2.3 times in hippocampal slices made hyperexcitable by perfusion with calcium-free artificial cerebrospinal fluid (aCSF). Furthermore, multiple neuronal dye coupling (triplets, quintuplets) was observed in these conditions but never in control (standard aCSF). Under conditions that reduce gap junctional conductance (intracellular acidification, octanol, halothane), seizure-like activity was suppressed in the CA1 area in this epilepsy model, whereas increasing gap junctional conductance by intracellular alkalinization increased the frequency and duration of field burst events. Intracellular acidification also reduced dye coupling as well as the frequency of fast prepotentials (electrotonic potentials) without altering neuronal firing frequency. Simultaneous extracellular field and single whole-cell recordings revealed suppression of synchronization between neuronal firing and spontaneous field burst activity during acidification. These observations indicate an apparent increase in electrotonic coupling during calcium-free induced spontaneous rhythmic field burst activity in the CA1 area of the hippocampus and that electrotonic coupling may contribute substantially to the synchronization of neuronal firing underlying seizure-like events. ER -