Role of Ca(2+)-activated potassium channels with high-conductivity in hypoxic preconditioning and posthypoxic hyperexcitability in CA1 hippocampal neurons in vitro

The role of highly conductive Ca(2+)-activated potassium channels (BK(Ca)-channels) of rat hippocampal CA1 neurons in the processes induced by repeated episodes of brief hypoxia was investigated. A specific blocker of BK(Ca)-channels iberiotoxin (10-20 nM) tended to decrease the efficiency of hypoxia in depressing the amplitude of population spikes during hypoxic episode. Iberiotoxin significantly abolished both the preconditioning effect of hypoxic episodes and the posthypoxic hyperexcitability of pyramidal neurons. It is suggested that BK(Ca)-channels play an important role in the mechanisms of such forms of neuroplasticity as rapid hypoxic preconditioning and posthypoxic hyperexcitability in hippocampal CA1 neurons.