title: Reactivation of inhibited bone acid phosphatase and its significance in bone histomorphometry.
abstract: Despite biochemical demonstration of acid phosphatase (AcP) activation or reactivation in bone, few attempts have been made to show similar effects histochemically. Bones from growing rats, when fixed in 4% buffered formaldehyde at room temperature and demineralized in 5% formic acid, exhibited expected inactivation of AcP. The inhibited AcP, however, was reactivated by pre-incubation of sections for 1 hr at 37 degrees C in the following buffers: 0.2 M Tris, 0.2 M glycine, 0.2 M NaHCO3, or 0.1 M borax, as well as in alkaline water, but not in 0.2 M Na2HPO4 (all at pH 9). The reactivation was (a) site-specific (e.g., osteoclasts, osteoblasts, osteocytes, and cement lines), (b) temperature- and pH-dependent, (c) unaffected by OH- or SH--binding agents or by an alkaline phosphatase inhibitor, and (d) inhibited completely by 10 mM Na2HPO4. The reactivation process, much simplified and/or more effective than with the methods previously reported, was observed in all 83 human biopsy bones embedded in methyl methacrylate and in human bones stored in cold buffered formaldehyde for 7 months. This study demonstrates a unique method for reactivating and thus localizing the inhibited AcP in bones, and suggests possible applications in bone histomorphometry.
authors: Department of Medicine, University of Washington, Seattle 98195.
authors: C C
authors: CC
authors: Liu
authors: D J
authors: DJ
authors: Sherrard
authors: N A
authors: NA
authors: Maloney
authors: G A
authors: GA
authors: Howard
mesh_terms: D000135:Acid Phosphatase / Q000378:metabolism*; D000818:Animals; D001842:Bone and Bones / Q000033:anatomy & histology / Q000201:enzymology*; D002021:Buffers; D002645:Chickens; D004789:Enzyme Activation; D004793:Enzyme Reactivators / Q000494:pharmacology; D005557:Formaldehyde / Q000494:pharmacology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D010010:Osteoclasts / Q000201:enzymology; D051381:Rats; D014325:Tromethamine / Q000494:pharmacology
chemical_list: D002021:Buffers; D004793:Enzyme Reactivators; D014325:Tromethamine; D005557:Formaldehyde; D000135:Acid Phosphatase