Voltage-dependent potassium channels (K+ channels) play a key role in the proper function of excitable tissues such as in the nervous system and the heart. In cardiac tissue, a variety of K+ channels fine tune the electrical events that lead to the modulation of the heartbeat. Research conducted under this proposal will yield information on the structural properties and biophysical characteristics of the various types of cardiac K+ channels. This will allow integration of the current contributed by an individual K+ channels to the total ionic current in different cardiac cell types. To achieve this, we will determine the structural diversity of human heart K+ channels by cloning cardiac cDNAs and their function by expression in Xenopus oocytes. A biophysical and pharmacological profile of both homotetrameric and, with coexpression, possible heterotetrameric K+ channel formation will be established. This will be followed by an examination of the spatial distribution and the relative abundance of the individual K+ channel subunits throughout the human heart using the polymerase chain reaction (PCR_ technique in combination with in situ hybridization and immunohistochemistry. To evaluate a role for K+ channels in cardiac pathologies, similar tests will be performed with diseased tissues. Such a functional characterization in combination with studies on channel distribution will serve as the basis to correlate the 'isolated' ionic currents detected with the 'pure' cloned channels with their physiological counterparts in cardiac tissues. A comparative molecular and electrophysiological description of cardiac K+ channels in normal and diseased tissues should lead to a better understanding of the electrical events underlying the heartbeat in normal and diseased states.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Program Projects (P01)
Project #
5P01HL037044-08
Application #
3780588
Study Section
Project Start
Project End
Budget Start
Budget End
Support Year
8
Fiscal Year
1993
Total Cost
Indirect Cost
Name
Baylor College of Medicine
Department
Type
DUNS #
074615394
City
Houston
State
TX
Country
United States
Zip Code
77030
Kiehn, J; Lacerda, A E; Brown, A M (1999) Pathways of HERG inactivation. Am J Physiol 277:H199-210
Accili, E A; Kuryshev, Y A; Wible, B A et al. (1998) Separable effects of human Kvbeta1.2 N- and C-termini on inactivation and expression of human Kv1.4. J Physiol 512 ( Pt 2):325-36
Suh-Kim, H; Wei, X; Birnbaumer, L (1996) Subunit composition is a major determinant in high affinity binding of a Ca2+ channel blocker. Mol Pharmacol 50:1330-7
Kiehn, J; Wible, B; Lacerda, A E et al. (1996) Mapping the block of a cloned human inward rectifier potassium channel by dofetilide. Mol Pharmacol 50:380-7
Dumaine, R; Wang, Q; Keating, M T et al. (1996) Multiple mechanisms of Na+ channel--linked long-QT syndrome. Circ Res 78:916-24
Jarolimek, W; Soman, K V; Alam, M et al. (1996) Structure-activity relationship of quaternary ammonium ions at the external tetraethylammonium binding site of cloned potassium channels. Mol Pharmacol 49:165-71
Pascual, J M; Shieh, C C; Kirsch, G E et al. (1995) K+ pore structure revealed by reporter cysteines at inner and outer surfaces. Neuron 14:1055-63
Crumb Jr, W J; Wible, B; Arnold, D J et al. (1995) Blockade of multiple human cardiac potassium currents by the antihistamine terfenadine: possible mechanism for terfenadine-associated cardiotoxicity. Mol Pharmacol 47:181-90
el-Hayek, R; Antoniu, B; Wang, J et al. (1995) Identification of calcium release-triggering and blocking regions of the II-III loop of the skeletal muscle dihydropyridine receptor. J Biol Chem 270:22116-8
Parent, L; Gopalakrishnan, M (1995) Glutamate substitution in repeat IV alters divalent and monovalent cation permeation in the heart Ca2+ channel. Biophys J 69:1801-13

Showing the most recent 10 out of 131 publications