title: A novel immunoassay for the determination of tartrate-resistant acid phosphatase 5b from rat serum.
abstract: Osteoclasts secrete tartrate-resistant acid phosphatase 5b (TRACP 5b) into the circulation. We have developed an immunoassay for the determination of rat TRACP 5b activity. Intra-assay variation of the immunoassay was 4.5%, interassay variation was 3.8%, dilution linearity was 104.6 +/- 7.6%, and recovery of recombinant rat TRACP was 99.1 +/- 5.8%. We studied serum TRACP 5b as a marker of bone resorption using orchidectomized (ORC) rats as a model for osteoporosis and age-matched sham-operated rats as controls in a 6-month study. After the operation, trabecular bone mineral density decreased significantly more in the ORC group than in the sham group, whereas cortical bone mineral density increased similarly in both groups. Serum TRACP 5b activity was significantly elevated within the first week after ORC, returned to the control level in the third week, and was not increased above the sham level at any of the later time points. At 6 months, trabecular bone volume was 80% lower in ORC rats than in controls. Osteoclast number per trabecular bone perimeter was slightly increased, but the absolute number of osteoclasts in trabecular bone was significantly decreased. These results suggest that absolute bone resorption is increased within the first week after ORC. Later, it is decreased because there is less bone to be resorbed. However, relative bone resorption (compared with the amount of remaining bone) is still increased, leading to further bone loss. We conclude that serum TRACP 5b is a useful marker for monitoring changes in the bone resorption rate in rat ORC model.
authors.affiliation: Department of Anatomy, Institute of Biomedicine, University of Turku, Turku, Finland.
authors.forename: Sari L
authors.initials: SL
authors.lastname: Alatalo
authors.forename: Zhiqi
authors.initials: Z
authors.lastname: Peng
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Janckila
authors.forename: Helena
authors.initials: H
authors.lastname: Kaija
authors.forename: Pirkko
authors.initials: P
authors.lastname: Vihko
authors.forename: H Kalervo
authors.initials: HK
authors.lastname: Vaananen
authors.forename: Jussi M
authors.initials: JM
authors.lastname: Halleen
mesh_terms: D000135:Acid Phosphatase / Q000097:blood* / Q000145:classification; D000818:Animals; D001774:Blood Chemical Analysis / Q000379:methods / Q000706:statistics & numerical data; D015519:Bone Density; D001862:Bone Resorption / Q000097:blood / Q000378:metabolism; D004195:Disease Models, Animal; D007118:Immunoassay / Q000379:methods* / Q000706:statistics & numerical data; D007527:Isoenzymes / Q000097:blood* / Q000145:classification; D008297:Male; D009919:Orchiectomy; D010024:Osteoporosis / Q000097:blood / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D000071681:Tartrate-Resistant Acid Phosphatase; D013997:Time Factors
chemical_list: D007527:Isoenzymes; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase