Elevations in extracellular potassium (K+e) accompany seizure-like events (SLEs), but elevated K+ may also participate in seizure cessation. The objective of this thesis was to investigate the possibility that K+ may undergo a pro- to anti-convulsant switch in the epileptic juvenile (postnatal day 17-21) rat hippocampus.
Field recordings were performed in the CA1 pyramidal layer. SLEs and primary afterdischarges (PADs) were induced with 0.25 mM Mg/5 mM K+ perfusion or tetanic stimulation of the Schaffer collaterals respectively. In these seizure models, elevating [K+]e beyond 7.5 mM showed anticonvulsant properties. The addition of ZD7288, a blocker of the hyperpolarization activated nonspecific cationic current (Ih) and allowed SLEs to continue even in elevated [K+]e. This suggests that [K+]e switches from being pro- to anti-convulsant, in part due to an elevated [K+]e-induced potentiation of Ih. Ih likely contributes to this anticonvulsant behavior by decreasing membrane resistance and subsequently attenuating summation of incoming EPSPs.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:OTU.1807/19009 |
| Date | 17 February 2010 |
| Creators | Yu, Wilson Jonathan |
| Contributors | Carlen, Peter Louis |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
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