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Cell-type specific expression of ATP-sensitive potassium channels in the rat hippocampus
C Zawar1, T D Plant, C Schirra
1I. Physiologisches Institut der Universitat des Saarlandes, D-66421 Homburg, Germany.
The Journal of Physiology
|December 16, 1998
Summary
ATP-sensitive potassium (KATP) channels are present in rat hippocampal neurons and glial cells. Their distribution and function vary significantly across different cell types, including CA1 pyramidal cells, interneurons, and granule cells.
Area of Science:
- Neuroscience
- Cellular Physiology
- Molecular Biology
Background:
- ATP-sensitive potassium (KATP) channels play crucial roles in cellular energy homeostasis and neuronal excitability.
- Understanding the distribution of KATP channels in different hippocampal cell types is essential for comprehending their functional significance.
Purpose of the Study:
- To investigate the distribution and functional expression of ATP-sensitive potassium (KATP) channels in distinct hippocampal cell populations.
- To characterize the molecular composition of KATP channels in CA1 pyramidal cells and interneurons using single-cell RT-PCR.
Main Methods:
- Patch-clamp electrophysiology was employed to assess KATP channel activity in response to specific openers (diazoxide) and inhibitors (tolbutamide, glibenclamide).
- Single-cell reverse transcription polymerase chain reaction (RT-PCR) was utilized to detect the expression of KATP channel subunit mRNAs (Kir6.1, Kir6.2, SUR1, SUR2).
- Neuronal cell types were identified visually, characterized by action potential properties, and confirmed with neurobiotin labeling.
Main Results:
- Functional KATP channels were detected in CA1 pyramidal cells (26%), interneurons (89%), glial cells (100%), and dentate gyrus granule cells (89%).
- Diazoxide activated KATP currents, which were inhibited by tolbutamide, confirming channel identity. Spontaneous currents were observed in ATP-free conditions.
- mRNA analysis revealed limited KATP channel subunit expression in pyramidal cells (17%), contrasting with higher expression in interneurons (75%), primarily Kir6.2/SUR1 combinations.
Conclusions:
- Functional ATP-sensitive potassium (KATP) channels are expressed across diverse hippocampal cell types, including principal neurons, interneurons, and glial cells.
- Significant variations in KATP channel density and subunit composition exist among these cell types, suggesting cell-specific roles.
- The findings highlight the widespread but differential presence of KATP channels in the hippocampus, impacting neuronal and glial function.
