Adenosine-mediated synaptic depression and EPSP/spike dissociation following high potassium-induced depolarization in rat hippocampal slices.
Simultaneous recordings of orthodromic PS, fEPSP and antidromic PS revealed EPSP/spike (E-S) dissociation, indicating a conversion of input/output relations from early and brief excitability to a late and prolonged depression during the recovery from depolarization induced by high levels of potassium. E-S potentiation was partially attenuated by pre-treating the slices with BAPTA-AM and lidocaine and totally eliminated by a submaximal concentration of muscimol. The time lag for recovery was decreased by the GABA(A) antagonist and completely eliminated by the A(1) antagonist. From these observations, we conclude that Ca(2+) dependent inhibitory suppression is the main cause of a brief period of E-S potentiation, and accumulation of adenosine is the mechanism responsible for prolonged depression of synaptic transmission
Park
Youn-Kwan
YK
Department of Neurosurgery, Korea University Guro Hospital, 80 Guro-dong, Guro-ku, Seoul 152-703, South Korea. ykapa@kumc.or.kr
Shim
Eun-Sheb
ES
Oh
Jae-In
JI
Kim
Joo-Han
JH
Chung
Yong-Gu
YG
D000241:Adenosine / Q000502:physiology*; D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D002614:Chelating Agents / Q000494:pharmacology; D004533:Egtazic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D004558:Electric Stimulation; D005071:Evoked Potentials / Q000187:drug effects; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology*; D018756:GABA Antagonists / Q000494:pharmacology; D006624:Hippocampus / Q000187:drug effects*; D066298:In Vitro Techniques; D002546:Ischemic Attack, Transient / Q000473:pathology; D008297:Male; D011188:Potassium / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013569:Synapses / Q000187:drug effects / Q000502:physiology*; D014970:Xanthines / Q000494:pharmacology
D002614:Chelating Agents; D018756:GABA Antagonists; D014970:Xanthines; D004533:Egtazic Acid; C051360:1,3-dipropyl-8-cyclopentylxanthine; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; D000241:Adenosine; D011188:Potassium; D001640:Bicuculline