Abstract
The effect of stimulation with continuous small amounts (15.5 microamperes) of electric current on the tibial periosteum of male Wistar rat was examined by 3H-thymidine autoradiography.
The autoradiographic study consisted of the following two methods; flash labeling and single pulse labeling methods.
Three treatment groups were established for the flash labeling method: In the first group, rat tibial periosteum was electrically stimulated with 15. 5 micro-amperes of constant direct current using wires made of silver and stainless steel twined round the tibial periosteum. The second group consisted of the wires only without electric stimulation as a control. In the third group, a non-treated periosteum was also established as a control. The animals in each group were sacrificed 1, 6, 12 and 18 hours, and 1, 2, 3, 4, 5, 7, and 10 days after initiation of electric stimulation and 3H-thymidine (74 KBq/g) was administered 1 hour before sacrifice.
Two treatment groups were established for the single pulse labeling method; The first and second groups were similar to those established for the flash labeling method without a third non-treated control group. Then 3H-thymidine (74 KBq/g) was administered 24 hours after electric stimulation and the animals were sacrificed immediately, 1, 2, 3, 4, 6, and 9 days after the administration.
This experiment revealed that a constant electric stimulation to the periosteum was effective for cell's differentiation to form electric callus. The electric stimulation began to proliferate osteoprogenitor cells from the cellular periosteum, followed by differentiation of osteogenic lineage cells and osteoblasts for osteoid formation. After that, the osteoblast matured to osteocytes within mineralized bone tissue.
