Potassium and calcium channel involvement in induction of long-lasting synaptic enhancement by calyculin A, a protein phosphatase inhibitor, in rat hippocampal CA1 region.
In the Schaffer collateral-CA1 pathway in rat hippocampal slices, exposure to calyculin A induced a long-lasting potentiation of the extracellular field potentials with a transient increase in glutamate release. The synaptic enhancement produced by calyculin A was blocked by staurosporine and nicardipine, but not by D,L-2-amino-5-phosphonovalerate. In dissociated CA1 pyramidal cells, calyculin A blocked the action-potential repolarization and fast after-hyperpolarization, and increased spike frequency. These results suggest that calyculin A-induced long-lasting potentiation is triggered by the blockade of Ca(2+)-activated K+ channels, the transient increase of glutamate release and the consequent activation of voltage-gated Ca2+ channels, and is maintained by increases in protein kinases activities.
Department of Pharmacology, Kobe University School of Medicine, Japan.
N
N
Murakami
N
N
Sakai
K
K
Nei
S
S
Matsuyama
N
N
Saito
C
C
Tanaka
D000818:Animals; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism*; D005071:Evoked Potentials / Q000187:drug effects / Q000502:physiology; D018698:Glutamic Acid / Q000378:metabolism; D006624:Hippocampus / Q000378:metabolism*; D066298:In Vitro Techniques; D017774:Long-Term Potentiation / Q000187:drug effects*; D008297:Male; D008387:Marine Toxins; D010080:Oxazoles / Q000494:pharmacology*; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors*; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects; D013569:Synapses / Q000187:drug effects*
D015220:Calcium Channels; D008387:Marine Toxins; D010080:Oxazoles; D015221:Potassium Channels; D016194:Receptors, N-Methyl-D-Aspartate; D018698:Glutamic Acid; C059041:calyculin A; D010749:Phosphoprotein Phosphatases