title: Red cell aspartate aminotransferase saturation with oral pyridoxine intake.
abstract: OBJECTIVE
  The coenzyme of aspartate aminotransferase is pyridoxal phosphate, generated from fresh vegetables containing pyridoxine. Vitamin B6-responsive sideroblastic anemia, myelofibrosis and Peyronies syndrome respond to high pyridoxine doses. The objective was to investigate the oral pyridoxine oral dose that would lead to maximized pyridoxal phosphate saturation of red cell aspartate aminotransferase.
  
  
  METHODS
  Controlled trial, in Hematology Division of Instituto Adolfo Lutz.
  
  
  METHODS
  Red cell aspartate aminotransferase activity was assayed (before and after) in normal volunteers who were given oral pyridoxine for 15-18 days (30 mg, 100 mg and 200 mg daily). In vitro study of blood from seven normal volunteers was also performed, with before and after assaying of aspartate aminotransferase activity.
  
  
  RESULTS
  The in vivo study showed increasing aspartate aminotransferase saturation with increasing pyridoxine doses. 83% saturation was reached with 30 mg daily, 88% with 100 mg, and 93% with 200 mg after 20 days of oral supplementation. The in vitro study did not reach 100% saturation.
  
  
  CONCLUSIONS
  Neither in vivo nor in vitro study demonstrated thorough aspartate aminotransferase saturation with its coenzyme pyridoxal phosphate in red cells, from increasing pyridoxine supplementation. However, the 200-mg dose could be employed safely in vitamin B6-responsive sideroblastic anemia, myelofibrosis and Peyronies syndrome treatment. Although maximum saturation in circulating red cells is not achieved, erythroblasts and other nucleated and cytoplasmic organelles containing cells certainly will reach thorough saturation, which possibly explains the results obtained in these diseases.
authors.affiliation: Hematology Division, Instituto Adolfo Lutz, Av. Dr. Arnaldo 355, São Paulo, Brazil CEP 01246-000. maoshiro@ial.sp.gov.br
authors.forename: Marilena
authors.initials: M
authors.lastname: Oshiro
authors.forename: Kimiyo
authors.initials: K
authors.lastname: Nonoyama
authors.forename: Raimundo Antônio Gomes
authors.initials: RA
authors.lastname: Oliveira
authors.forename: Orlando Cesar de Oliveira
authors.initials: OC
authors.lastname: Barretto
mesh_terms: D000328:Adult; D001219:Aspartate Aminotransferases / Q000097:blood*; D019587:Dietary Supplements; D004912:Erythrocytes / Q000187:drug effects / Q000201:enzymology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011732:Pyridoxal Phosphate / Q000494:pharmacology; D011736:Pyridoxine / Q000008:administration & dosage*; D013997:Time Factors
chemical_list: D011732:Pyridoxal Phosphate; D001219:Aspartate Aminotransferases; D011736:Pyridoxine