Linked Life Data

8647856

Source:http://linkedlifedata.com/resource/pubmed/id/8647856

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
21
pubmed:dateCreated
1996-7-22
pubmed:abstractText
We used highly purified avian osteoclasts and isolated membranes from osteoclasts to study effects of tamoxifen, 4-hydroxytamoxifen, calmodulin antagonists, estrogen, diethylstilbestrol, and the anti-estrogen ICI 182780 on cellular degradation of 3H-labeled bone in vitro and on membrane HCl transport. Bone resorption was reversibly inhibited by tamoxifen, 4-hydroxytamoxifen, and trifluoperazine with IC50 values of approximately 1 microM. Diethylstilbestrol and 17-beta-stradiol had no effects on bone resorption at receptor-saturating concentrations, while ICI 182780 inhibited bone resorption at concentrations greater than 1 microM. At these concentrations ICI 182780, like tamoxifen, inhibits calmodulin-stimulated cyclic nucleotide phosphodiesterase activity. Membrane HCl transport, assessed by ATP-dependent acridine orange uptake, was unaffected by 17-beta-estradiol and diethylstilbestrol at concentrations up to 10 microM, while ICI greater than 1 microM. In contrast HCl transport was inhibited by tamoxifen, 4-hydroxytamoxifen, and the calmodulin antagonists, trifluoperazine and the calmidazolium, with IC50 values of 0.25-1.5 microM. These results suggested the presence of a membrane-associated non-steroid receptor for tamoxifen in osteoclasts. Tamoxifen binding studies demonstrated saturable binding in the osteoclast particulate fraction, but not in the nuclear or cytosolic fractions. Membranes enriched in ruffled border by differential centrifugation following nitrogen cavitation showed binding consistent with one site, Kd approximately microM. Our findings indicate that tamoxifen inhibits osteoclastic HCl transport by binding membrane-associated target(s), probably similar or related to calmodulin antagonist targets. Further, effects of estrogens or highly specific anti-estrogens on bone turnover do not support the hypothesis of a direct effect on osteoclasts by these compounds in this species.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
24
pubmed:volume
271
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
12488-95
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1996
pubmed:articleTitle
Regulation of avian osteoclastic H+ -ATPase and bone resorption by tamoxifen and calmodulin antagonists. Effects independent of steroid receptors.
pubmed:affiliation
Department of Pathology, University of Alabama at Birmingham, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, U.S. Gov't, Non-P.H.S.