title: Functional Na+ channels in cell adhesion probed by transistor recording.
abstract: Cell membranes in a tissue are in close contact to each other, embedded in the extracellular matrix. Standard electrophysiological methods are not able to characterize ion channels under these conditions. Here we consider the area of cell adhesion on a solid substrate as a model system. We used HEK 293 cells cultured on fibronectin and studied the activation of Na(V)1.4 sodium channels in the adherent membrane with field-effect transistors in a silicon substrate. Under voltage clamp, we compared the transistor response with the whole-cell current. We observed that the extracellular voltage in the cell-chip contact was proportional to the total membrane current. The relation was calibrated by alternating-current stimulation. We found that Na(+) channels are present in the area of cell adhesion on fibronectin with a functionality and a density that is indistinguishable from the free membrane. The experiment provides a basis for studying selective accumulation and depletion of ion channels in cell adhesion and also for a development of cell-based biosensoric devices and neuroelectronic systems.
authors.affiliation: Department of Membrane and Neurophysics, Max Planck Institute for Biochemistry, Martinsried/Munich, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Schmidtner
authors.forename: Peter
authors.initials: P
authors.lastname: Fromherz
mesh_terms: D000200:Action Potentials; D001703:Biophysics / Q000379:methods*; D002138:Calibration; D002448:Cell Adhesion; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D004573:Electrolytes; D004594:Electrophysiology; D005353:Fibronectins / Q000737:chemistry; D006801:Humans; D015640:Ion Channel Gating; D007473:Ion Channels / Q000737:chemistry; D007477:Ions; D051036:Large-Conductance Calcium-Activated Potassium Channels / Q000737:chemistry; D008564:Membrane Potentials; D009124:Muscle Proteins / Q000737:chemistry; D062553:NAV1.4 Voltage-Gated Sodium Channel; D018408:Patch-Clamp Techniques; D015221:Potassium Channels; D012825:Silicon / Q000737:chemistry; D012964:Sodium / Q000737:chemistry; D015222:Sodium Channels / Q000737:chemistry*; D013997:Time Factors; D014162:Transfection; D014173:Transistors, Electronic
chemical_list: D004573:Electrolytes; D005353:Fibronectins; D007473:Ion Channels; D007477:Ions; D051036:Large-Conductance Calcium-Activated Potassium Channels; D009124:Muscle Proteins; D062553:NAV1.4 Voltage-Gated Sodium Channel; D015221:Potassium Channels; C106251:SCN4A protein, human; D015222:Sodium Channels; D012964:Sodium; D012825:Silicon