The aim of this study was to investigate the comparative effects of
glibenclamide (GC), a selective blocker of K(+)(
ATP) channels, and
iberiotoxin (
IbTX), a selective blocker of BK(+)(Ca) channels, on the repeated brief
hypoxia-induced posthypoxic hyperexcitability and rapid hypoxic preconditioning in hippocampal CA1 pyramidal neurons in vitro. The method of field potentials measurement in CA1 region of the rat hippocampal slices was used. In contrast to GC (10 microM),
IbTX (10nM) significantly abolished both posthypoxic hyperexcitability and rapid hypoxic preconditioning induced by brief hypoxic episodes. These effects of
IbTX did not depend on its ability to reduce the
hypoxia-induced decrease of population spike (PS) amplitude during hypoxic episodes since GC (10 microM), comparatively with
IbTX (10nM), significantly reduced the depressive effect of
hypoxia on the PS amplitude during hypoxic episodes but did not abolish both posthypoxic hyperexcitability and rapid hypoxic preconditioning in CA1 pyramidal neurons. Our results indicated that BK(+)(Ca) channels, in comparison with K(+)(
ATP) channels, play a more important role in such repeated brief
hypoxia-induced forms of neuroplasticity in hippocampal CA1 pyramidal neurons as posthypoxic hyperexcitability and rapid hypoxic preconditioning.