Capacitive pulsed electrical stimulation of bone cells: Induction of calcium uptake

Exposure of bone cells in culture to capacitively coupled external electric fields induced calcium uptake. The extent of the uptake increased with the strength (12-54 V /cm) and frequency (3-100 Hz) of the applied electric field. Calcium uptake was shown to depend on the external calcium concentration yielding a maximal relative increase by the electric field for an extracellular calcium concentration of 1.5 m M. Electric-field-induced calcium uptake was shown to depend on the proximity of the plastic surface on which the cells adhered to the anode or to the cathode. An increased calcium uptake was observed when the bone cells adhered to the substratum which was close to the anode as compared to the cathode. This anisotropy with regard to the direction of the electric field suggests an uneven distribution of calcium transport systems in the plasma membrane probably due to the attachment of the cells to the plastic substratum. It is proposed that calcium influx, driven by the induced polarization of the plasma membrane when bone cells are exposed to external electric fields, acts via a classical second messenger mechanism leading eventually to a mitogenic effect.