The role of the BKCa channel in adenosine receptor-mediated cytoprotection

Fretwell, L.V., 2009. The role of the BKCa channel in adenosine receptor-mediated cytoprotection. PhD, Nottingham Trent University.

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Abstract

The rat embryonic cardiomyoblast-derived H9c2 cell line is increasingly used for studies into cardioprotection, as these cells display similar properties to primary cardiomyocytes. Adenosine receptors are well known mediators of cardioprotection and trigger effectors such as the mitochondrial KATP channel - however, the role of the mitochondrial BKCa channel in adenosine receptor-mediated cardioprotection has not been investigated. GPCR assays provided evidence for functional expression of Gi-coupled adenosine A1 and K-opioid receptors, Gs-coupled β2 adrenergic receptors and Gq-coupled UTP-binding P2Y purinergic receptors on H9c2 cells. Activation of the adenosine A1 receptor with CPA (N(6)-cyclopentyladenosine) provided significant protection against hypoxia-induced cell death in these cells, as did opening of a BKCa channel with NS1619. The location of this BKCa channel was confinned to be the mitochondria by the probing of subcellular fractions with BKCa-specific antibodies. Interestingly, CPA-induced protection against hypoxia was blocked by inhibition of the BKCa channel. In a model of hypoxia/reoxygenation in H9c2 cells both CPA and NS1619 significantly reduced cell death when used as postconditioning agents, and in both cases the protection was abolished by blockade of the BKCa channel. This data suggests for the first time that, in H9c2 cells, the BKCa channel is involved in A1 receptor-mediated cytoprotection. To confirm this finding in a more physiologically relevant model - and validate the use of H9c2 cells as a model for cardioprotection -hypoxia/reoxygenation in isolated rat ventricle strips was investigated. It was discovered that blockade of the BKCa channel significantly attenuated protection afforded by hypoxia preconditioning and preconditioning triggered by activation of the adenosine A1 and A2A receptors.

For the first time, this report has shown an important role for the BKCa channel in adenosine receptor-mediated cytoprotection.

Item Type:	Thesis
Creators:	Fretwell, L.V.
Date:	2009
ISBN:	9781369314236
Identifiers:	Number Type PQ10183148 Other
Rights:	This work is the intellectual property o f the author and Nottingham Trent University. You may copy up to 5% of this work for private study, or personal, non-commercial research. Any re-use of the information contained within this document should be fully referenced, quoting the author, title, university, degree level and pagination. Queries or requests for any other use, or if a more substantial copy is required, should be directed in the first instance to the author.
Divisions:	Schools > School of Science and Technology
Record created by:	Linda Sullivan
Date Added:	18 Sep 2020 09:17
Last Modified:	26 Jul 2023 11:00
URI:	https://irep.ntu.ac.uk/id/eprint/40794

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