Cardiovascular Ion Channels

Our research involves a multi-disciplinary approach to the study of cardiovascular ion channels. Our major interests focus on ATP and voltage-sensitive potassium channels and L-type calcium channels. Projects range from detailed structure-function analyses through single-cell studies to whole vessel pharmacology. We employ a wide range of techniques including; expression of recombinant ion channel subunits, mutagenesis, co-immuneprecipitation, immunohistochemistry, patch clamp electrophysiology (using both cultured and native cells), RNA interference, calcium imaging and myography (both wire & pressure). Active members are; Bob Norman (biochemistry), Dave Lodwick (molecular biology) and Rich Rainbow (electrophysiology).

Examples of current and recent projects

Adult cardiac myocytes are notoriously difficult to transfect. We have developed successful strategies to overcome this problem using both lipid-based (Rainbow et al. 2004b) and viral methods. Also, in collaboration with colleagues in Cell Physiology and Pharmacology, we have established methods for culturing, transfecting and recording ionic currents from cultured smooth muscle cells. These technologies will give us the tools to investigate the fundamental role of ion channels in the biology of these key cardiovascular cell types.

We have developed an adenoviral delivery system for RNA interference and are using the approach to investigate the role of K_ATP subunit isoforms in ischaemic preconditioning, in collaboration with Dr Nina Storey (Cell Physiology and Pharmacology). We have also developed luciferase-based methods for evaluating shRNA efficiency in cultured cells.

We have identified a crucial site of interaction between the pore-forming Kir6.0 and modulatory sulphonylurea subunits of K_ATP channels (Rainbow et al. 2004a) and are investigating its role in allosteric information transfer. We have used the dominant-negative properties of SUR peptides to demonstrate the critical role played by K_ATP channels in the ischaemic tolerance of cardiac myocytes (Rainbow et al. 2004b).

We have used Tat-linked inhibitor peptides to elucidate the signalling pathways responsible for cardiovascular ion channel modulation in smooth and cardiac muscle (Rainbow et al. 2009).   Using Tat-linked PKC inhibitor peptides we have characterised the responses to the vasoconstrictors angiotensin II and endothelin. In addition, we have demonstrated that the response of vascular smooth muscle to endothelin is modulated by glucose (Rainbow et al. 2006).  We have also demonstrated that glucose modulates the cardiac action potential through a glucose-sensitive PKC-dependent mechanism.