Quantification of osteoclastic resorption of the bovine otic capsule in vitro by an enzyme-linked immunosorbent assay.
The bony shell surrounding the inner ear is known to have a very pronounced centripetal inhibition of remodelling in vivo, with almost no bone turnover immediately adjacent to the perilymphatic spaces and a gradually increasing turnover rate towards outer parts of the bony otic capsule. By the use of in vitro markers of bone resorption, including an enzyme-linked immunosorbent assay for quantification of type I collagen degradation and a colorimetric enzyme assay for quantification of osteoclast tartrate-resistant acid phosphatase activity, this study demonstrates that there are no ex vivo differences in bone matrix resorption between the inner and outer parts of the otic capsule when exposed to seeded osteoclasts from rabbits. Thus, the unique spatial distribution of perilabyrinthine bone turnover is not caused by a shift in resorbability from inner to outer capsular bone that is due to inherent bone quality differences particular to these bone compartments. More likely, the sustained action of some intravital 'field force', originating from the inner ear spaces, is responsible for the unique spatial distribution of the otic capsular bone turnover found in vivo. Though the character of this force is not yet defined, it is appealing to relate it to the large electromagnetic potential gradient present in the inner ear.
Frisch
T
T
Otopathological Laboratory, Department of Otolaryngology, Head and Neck Surgery, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark. tfrisch@rh.dk
Foged
N T
NT
Sørensen
M S
MS
Bretlau
P
P
D000704:Analysis of Variance; D000818:Animals; D001862:Bone Resorption / Q000473:pathology*; D002417:Cattle; D002478:Cells, Cultured; D003094:Collagen / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D066298:In Vitro Techniques; D010010:Osteoclasts / Q000378:metabolism*; D011817:Rabbits; D013701:Temporal Bone / Q000502:physiology*
D003094:Collagen