title: Monofluorophosphate is hydrolyzed by alkaline phosphatase and mimics the actions of NaF on skeletal tissues, in vitro.
abstract: These studies were intended to assess the osteogenic activity of monofluorophosphate (MFP) in vitro, and to identify the enzyme(s) responsible for MFP hydrolysis-alkaline phosphatase (ALP) and/or acid phosphatase (AcP). ALP and AcP activities were determined by hydrolysis of p-nitrophenylphosphate (PNPP) at pH greater than 8 and pH 5.5, respectively, and MFP hydrolysis was determined, between pH 5.5 and pH 9.0, from measurements of [fluoride ion], using an ion-specific electrode. We found (1) that MFP was an alternative substrate for purified ALP, but not for AcP; (2) that MFPase activity in the embryonic chick resembled ALP, but not AcP, with respect to pH-dependent hydrolysis, sensitivity to effectors (r = 0.98, P less than .001), and tissue distribution (r = 0.96, P less than .001); and (3) that intestinal MFPase activity in the embryonic chick co-purified with ALP activity (r = 0.93, P less than .01) and resembled ALP, but not AcP, in its distribution along the small intestine, being highest in the duodenum and lowest in the distal ileum (r = 0.96, P less than .001). We also found that in vitro exposure to MFP increased (1) the proliferation rate of embryonic chick calvarial cells in serum-free monolayer cultures (i.e., 3[H]-thymidine incorporation into DNA, P less than .001); (2) ALP activity in calvarial cells (P less than .005) and in intact calvaria (P less than .05); and (3) collagen production by intact calvaria (i.e., 3[H]-proline incorporation as 3[H]-hydroxyproline, P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000135:Acid Phosphatase / Q000378:metabolism; D000469:Alkaline Phosphatase / Q000378:metabolism*; D000818:Animals; D001842:Bone and Bones / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D002642:Chick Embryo; D003094:Collagen / Q000096:biosynthesis; D005459:Fluorides / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007421:Intestine, Small / Q000201:enzymology; D010710:Phosphates / Q000378:metabolism* / Q000494:pharmacology; D012969:Sodium Fluoride / Q000494:pharmacology*
chemical_list: D010710:Phosphates; C012980:fluorophosphate; D012969:Sodium Fluoride; D003094:Collagen; D000469:Alkaline Phosphatase; D000135:Acid Phosphatase; D005459:Fluorides