Molecular basis of functional voltage-gated K+ channel diversity in the mammalian myocardium.
In the mammalian heart, Ca2+-independent, depolarization-activated potassium (K+) currents contribute importantly to shaping the waveforms of action potentials, and several distinct types of voltage-gated K+ currents that subserve this role have been characterized. In most cardiac cells, transient outward currents, Ito,f and/or Ito,s, and several components of delayed reactivation, including IKr, IKs, IKur and IK,slow, are expressed. Nevertheless, there are species, as well as cell-type and regional, differences in the expression patterns of these currents, and these differences are manifested as variations in action potential waveforms. A large number of voltage-gated K+ channel pore-forming (alpha) and accessory (beta, minK, MiRP) subunits have been cloned from or shown to be expressed in heart, and a variety of experimental approaches are being exploited in vitro and in vivo to define the relationship(s) between these subunits and functional voltage-gated cardiac K+ channels. Considerable progress has been made in defining these relationships recently, and it is now clear that distinct molecular entities underlie the various electrophysiologically distinct repolarizing K+ currents (i.e. Ito,f, Ito,s, IKr, IKs, IKur, IK,slow, etc.) in myocyardial cells.
Nerbonne
J M
JM
Department of Molecular Biology and Pharmacology, Washington University Medical School, St Louis, MO 63110, USA. jnerbonn@pcg.wustl.edu
D000200:Action Potentials; D000818:Animals; D006801:Humans; D066298:In Vitro Techniques; D015640:Ion Channel Gating; D008958:Models, Molecular; D009206:Myocardium / Q000378:metabolism*; D015221:Potassium Channels / Q000737:chemistry* / Q000378:metabolism*
D015221:Potassium Channels