Clay Margrave Armstrong, M.D.

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Emeritus Professor of Physiology
Department: Physiology
Graduate Group Affiliations

Contact information
A701 Richards Building
University of Pennsylvania School of Medicine
Philadelphia, PA 19104-6085
Office: (215) 898-7816
Fax: (215) 573-5851
Rice University, Houston, TX, 1956.
Washington University, School of Medicine, St. Louis, MO, 1960.
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Description of Research Expertise

Transmembrane ionic channels and membrane potentials are properties common to all cells. My laboratory works on permeability mechanisms of ionic channels, the gating processes that open and close the channels, and the role of channels and membrane potentials in cell function.

Sodium and potassiun channels in excitable membranes are activated by changes of the membrane voltage. The laboratory is examining the gating of these channels in the membranes of one of the classical excitable cells, the squid giant axon. In this preparation, the investigator can control the solution bathing the internal and external surfaces of the membrane, and very rapid changes of the membrane potential can be imposed, allowing excellent time resolution of the gating processes. Gating current, an important indicator of gating activity, can best be measured from squid giant axons.

Excitability is a property of many cells, including endocrine cells. Cells derived from the pituitary have action potentials and pacemaking activity, and a full complement of ionic channels, including sodium channels, 2 or more types of potassium channels, and at least 2 types of calcium channels. My research is examining these cells using the patch clamp technique, and is attempting to extend studies of this type to neurons from the central nervous system (CNS) to achieve a better understanding of the cellular electrophysiology of these complex cells.

Selected Publications

Armstrong, C.M.: The Na/K Pump, Chloride Ion, and Osmotic Stabilization of Cells. PNAS 100(10): 6257-6262, 2003.

Armstrong, C.M.: Voltage-gated K channels. Sci STKE 188: RE10, 2003.

Armstrong, C.M.: Channels and Pumps Early in Evolution. Epithelia, Pumps, Transporters and Ion Channels. F. Bezanilla and F. Sepulveda (eds.). 2002.

Gomez-Lagunas, F., Melishchuk, A., and Armstrong, C.M.: Block of Shaker potassium channels by external Ca2+. PNAS 100(1): 347-351, 2002.

Melishchuk A., Armstrong CM.: Mechanism underlying slow kinetics of the OFF gating current in Shaker potassium channel. Biophysical Journal 80(5): 2167-75, May 2001.

Loboda, A., A. Melishchuk, and C.M. Armstrong: Dilated and defunct K channels in the absence of K+ Accepted for publication, Biophys. J 2001.

Loboda, A. and C.M. Armstrong: Resolving the gating charge movement associated with late transitions in K channel activation. Accepted for publication, Biophys. J 2001.

Armstrong, C.M. and A. Loboda: A model for 4-aminopyridine action on K channels. Similarities to TEA+ action. Accepted for publication, Biophys. J 2001.

Hong, K.H., Armstrong, C.M., & Miller C.: Revisiting the role of Ca2+ in Shaker K+ channel gating. Biophys J. 80: 2216-2220, 2001.

Hille B., Armstrong CM., MacKinnon R.: Ion channels: from idea to reality. Nature Medicine 5(10): 1105-9, Oct 1999.

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Last updated: 09/08/2004
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