title: Determination of alkaline phosphatase isozymes in amniotic fluid.
abstract: A simple method for the determination of the three isozymes of alkaline phosphatase (EC 3.1.3.1) contained in amniotic fluid (fetal intestinal, placental, and liver-bone-kidney) is presented. Total alkaline phosphatase activity was assayed in 10,000 g supernatants of amniotic fluid from 30 normal women between the 16th and 20th week of pregnancy. Electrophoretic patterns and inhibition by L-phenylalanine and L-homoarginine studies showed that all the fetal intestinal isozyme was precipitated in the pellet after centrifugation at 100,000 g for 90 min. Thus, the difference between total alkaline phosphatase activity and activity in the 100,000 g supernatant corresponds to fetal intestinal alkaline phosphatase. Placental isozyme can be determined by assaying alkaline phosphatase in the 100,000 g supernatant after heating at 56 degrees C for 90 min. Liver-bone-kidney isozyme activity is obtained by subtracting placental alkaline phosphatase activity from that of the 100,000 g supernatant. Mean percentages of the total alkaline phosphatase for each of the isozymes in amniotic fluid were 81% for fetal intestinal alkaline phosphatase, 7.5% for placental alkaline phosphatase and 12.0% for liver-bone-kidney alkaline phosphatase. Determination of fetal intestinal alkaline phosphatase by this method could be applied to the diagnosis of cystic fibrosis in fetuses having a 1:4 risk of being affected.
authors.affiliation: Cátedra de Quimica Biológica, Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Argentina.
authors.forename: A
authors.initials: A
authors.lastname: Sembaj
authors.forename: C
authors.initials: C
authors.lastname: Carriazo
authors.forename: E
authors.initials: E
authors.lastname: Sanz
authors.forename: J
authors.initials: J
authors.lastname: Moreno Barral
mesh_terms: D000328:Adult; D000469:Alkaline Phosphatase / Q000032:analysis* / Q000378:metabolism; D000653:Amniotic Fluid / Q000201:enzymology*; D005260:Female; D006801:Humans; D007527:Isoenzymes / Q000032:analysis* / Q000378:metabolism; D011247:Pregnancy
chemical_list: D007527:Isoenzymes; D000469:Alkaline Phosphatase