Low calcium-induced epileptiform activity in hippocampal slices from infant rats

Ca2+-free solutions evoke spontaneous epileptiform activity in area CA1 of hippocampal slices from adult and young rats at the age of 7/8, 14/15 and 23/24 days. Studies with combined Ca2+-selective and K+-selective microelectrodes showed that this epileptiform activity commenced at higher Ca2+ levels in young than in adult animals. Unlike in disinhibition seizures, [K+]o did not rise to abnormally high levels. We further found that Ca2+ washout curves from young animals were much faster than those from adult slices, suggesting that the extracellular space is wider in young animals than in adult ones.