Amelioration of oxygen-induced osteoporosis in the in vitro fetal rat tibia with a capacitively coupled electrical field.
Near-term fetal rat tibiae were grown in M.E.M. Eagle/NCTC 135/15% newborn calf serum in 5% carbon dioxide and 5, 10, 21, 35, 60, and 90% oxygen for 3, 7, 10, and 14 days. Linear growth of the explants, as measured from macrophotographs of the explants at day zero and each of the days above, was greatest in the lower oxygen concentrations and least in the higher oxygen concentrations. Breaking strengths of the tibial diaphyses were significantly reduced in those explants grown in 60 and 90% oxygen. When the fetal rat tibiae were grown in 60% oxygen for 7 days and were subjected to a capacitively coupled electrical signal (sine wave, 60 kHz, 10 V peak-to-peak output signal; current density and field in the culture dish calculated to be 5.2 microA/cm2 and 0.32 mV/cm, respectively), the breaking strengths and middiaphyseal widths were statistically significantly greater than control tibiae grown in 60% oxygen alone. It is concluded that an appropriate capacitively coupled electrical field can inhibit an oxygen-induced osteoporosis in an in vitro mammalian long bone model.