Clay Armstrong, MD

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				Clay M. Armstrong, M.D. Professor, Department of Physiology School of Medicine C701 Richards Bldg/6085 (215) 898-7816 Click here for selected publications since Dr. Armstrong 's arrival at Penn RESEARCH INTERESTS Ionic channels and their gating mechanisms RESEARCH TECHNIQUES Voltage clamp and patch clamp RESEARCH SUMMARY 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 potassium channels in excitable membranes are activated by changes of the membrane voltage. We examine the gating of these channels in the membranes of one of the classical excitable cells, the squid giant axon. In this preparation one 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, two or more types of potassium channels and at least two types of calcium channels. We are currently examining these cells using the patch clamp technique. We are attempting to extend studies of this type to neurons from the central nervous system, to achieve a better understanding of the cellular electrophysiology of these complex cells.