Effects of K+ channel modulators on extracellular K+ accumulation during ischemia in the rat hippocampal slice
The Korean Journal of Physiology and Pharmacology
;
: 681-690, 1997.
Artigo
em Inglês
| WPRIM
| ID: wpr-727963
ABSTRACT
Loss of synaptic transmission and accumulation of extracellular K+((K+)o) are the key features in ischemic brain damage. Here, we examined the effects of several K+ channel modulators on the early ischemic changes in population spike (PS) and (K+)o in the CA1 pyramidal layer of the rat hippocampal slice using electrophysiological techniques. After onset of anoxic aglycemia (AA), orthodromic field potentials decreased and disappeared in 3.3 +/- 0.22 min (mean +/- SEM, n = 40). The hypoxic injury potential (HIP), a transient recovery of PS appeared at 6.0 +/- 0.25 min (n = 40) in most slices during AA and lasted for 3.3 +/- 0.43 min. (K+)o increased initially at a rate of 0.43 mM/min (Phase 1) and later at a much faster rate (12.45 mM/min, Phase 2). The beginning of Phase 2 was invariably coincided with the disappearance of HIP. Among K+ channel modulators tested such as 4-aminopyridine (0.03, 0.3 mM), tetraethylammonium (0.1 mM), NS1619 (0.3 ~ 10 muM), niflumic acid (0.1 mM), glibenclamide (40 muM), tolbutamide (300 muM) and pinacidil (100 muM), only 4-aminopyridine (0.3 mM) induced slight increase of (K+)o during Phase 1. However, none of the above agents modulated the pattern of Phase 2 in (K+)o in response to AA. Taken together, the experimental data suggest that 4-aminopyridine-sensitive K+ channels, large conductance Ca2+/-activated K+ channels and ATP-sensitive K+ channels may not be the major contributors to the sudden increase of (K+)o during the early stage of brain ischemia, suggesting the presence of other routes of K+ efflux during brain ischemia.
Texto completo:
DisponíveL
Índice:
WPRIM (Pacífico Ocidental)
Assunto principal:
Tolbutamida
/
Encéfalo
/
4-Aminopiridina
/
Isquemia Encefálica
/
Ácido Niflúmico
/
Glibureto
/
Transmissão Sináptica
/
Tetraetilamônio
/
Pinacidil
/
Quadril
Limite:
Animais
Idioma:
Inglês
Revista:
The Korean Journal of Physiology and Pharmacology
Ano de publicação:
1997
Tipo de documento:
Artigo
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