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 NaV1.4 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 ac 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.
DC coupling of Na+ channels to transistor. (a) Membrane current IM(t) versus time for 15 different voltage pulses with a duration of 10 ms starting from a holding voltage of 120 mV (inset). (b) Extracellular voltage in the cell-chip junction VJ(t) versus time. Twenty signals are averaged for IM(t) and VJ(t) at each membrane voltage.
rss
Top
Print