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Proliferative and synthetic response of bovine growth plate chondrocytes to various capacitively coupled electrical fields
Author(s) -
Brighton Carl T.,
Jensen Loren,
Pollack Solomon R.,
Tolin Brad S.,
Clark Charles C.
Publication year - 1989
Publication title -
journal of orthopaedic research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.041
H-Index - 155
eISSN - 1554-527X
pISSN - 0736-0266
DOI - 10.1002/jor.1100070519
Subject(s) - duty cycle , thymidine , dna synthesis , in vitro , biophysics , chemistry , matrix (chemical analysis) , cell growth , materials science , biology , biochemistry , voltage , electrical engineering , chromatography , engineering
In vitro monolayer cultures of growth plate chondrocytes isolated from newborn calf costochondral junctions were subjected to capacitively coupled electrical fields for 48 h. In part A, the electrical signal was a 60‐kHz sine wave applied at different voltages so as to produce electrical fields at the pericellular level of 7, 20, 50, and 126 mV/cm. Incorporations of [ 3 H]thymidine and [ 35 S]sulfate were assayed to determine the effect of the above fields on cell proliferation and matrix synthesis, respectively. Proliferation was increased by 47% in the 20 mV/cm field whereas the same field decreased [ 35 S]sulfate incorporation by 21%. These changes were significant at p < 0.05 in both instances. In part B, the 20 mV/cm field was applied in a pulsed fashion to produce daily duty cycles of 100. 25, 2, and 0.25%. Incorporation of [ 3 H]thymidine, [ 35 S]sulfate, and [ 14 C]proline per DNA were assayed. Results indicated that the 100, 25, and 0.25% percent duty cycles showed significantly (p < 0.01–0.05) increased proliferation, whereas the 0.25% signal (5 ms on/495 ms off for 6 h/day) significantly decreased [ 14 C]proline incorporation. We conclude that the biologic response of cells in vitro is signal specific, and that the total amount of electrical energy required to stimulate the growth plate chondrocyte to increased proliferation is very small since the total time the 0.25% duty cycle signal was only 3.6 min of a 24‐h period.