| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1994: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1993: ¥1,300,000 (Direct Cost: ¥1,300,000)
|
|---|
| Research Abstract |
We have found previously that when osteoclasts isolated from newborn rabbit long bone were cultured on bovine bone slices for 48h at pH6.5 (low), resorptive activity was high, whereas when cultured at pH7.5 (normal) resorptive activity was negligible.We have now investigated whether "inactive" osteoclasts maintained at normal pH for 24h can be "activated" by transferring to low pH medium and, conversely, whether "activated" osteoclasts in 24h low pH cultures become inactive when transferred to normal pH.Osteoclast-containing cell populations were prepared from long bones of 1 day old rabbits and seeded onto bovine bone slices. The cells were allowed to attach for 1.5h, after which 2ml of medium at pH6.5 or 7.5 was added. After 24h at 37ﾟC in air, the culture media were changed and continued for another 24h. The cultures were stained for tartrate resistant acid phosphatase (TRAP) to localize multinucleated osteoclasts. The results show that nonresorbing osteoclasts can be activated by decreasing the pH of the medium from 7.5 to 6.5 and that actively resorbing osteoclasts stop resorbing when transferred to media of pH7.5. These observations indicate that increased osteoclast numbers do not necessarily correlate with increased resorptive activity. Ginival fibloblasts and periodontal ligament cells which cultured in low pH medium dicrease the expression of mRNA,proteoglycan specific as well as dicrease the production of proteoglycas. Cytoplasmic pH in osteoclasts which cultured with osteoclastic activity inhibitory factores, calcitonin etc., dicrease when measured by DAMP-HCl.
|
