Comparative roles of ATP-sensitive K+ channels and Ca2+-activated BK+ channels in posthypoxic hyperexcitability and rapid hypoxic preconditioning in hippocampal CA1 pyramidal neurons in vitro.
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.
Levin
Sergei G
SG
Institute of Theoretical and Experimental Biophysics of the Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia.
Godukhin
Oleg V
OV
D000200:Action Potentials; D000818:Animals; D015687:Cell Hypoxia; D005905:Glyburide / Q000494:pharmacology; D006624:Hippocampus / Q000166:cytology*; D066298:In Vitro Techniques; D019194:Ischemic Preconditioning; D054086:KATP Channels / Q000037:antagonists & inhibitors / Q000502:physiology*; D051036:Large-Conductance Calcium-Activated Potassium Channels / Q000037:antagonists & inhibitors / Q000502:physiology*; D008297:Male; D009473:Neuronal Plasticity; D010455:Peptides / Q000494:pharmacology; D017966:Pyramidal Cells / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar
D054086:KATP Channels; D051036:Large-Conductance Calcium-Activated Potassium Channels; D010455:Peptides; C064719:iberiotoxin; D005905:Glyburide