title: Assessment of xanthine oxidase in human lung and lung transplantation.
abstract: Oxygen free radical generation by xanthine oxidase (XO) is a possible mechanism in the injury following reperfusion of transplanted organs. This study was undertaken to investigate XO in human lung, and to investigate whether XO is released into the blood stream during the immediate postoperative period after lung transplantation. XO activity was measured in healthy human lung tissue, and XO protein and the adenine nucleotide catabolic products hypoxanthine, xanthine and uric acid were analysed in the plasma samples collected during human heart-lung transplantation (n=4), double lung transplantation (n=2), and single lung transplantation (n=1). Neutrophil degranulation was assessed by plasma lactoferrin measurements. The results indicated that XO activity (detection limit 5 pmol x min(-1) x mg(-1) protein) and protein (detection limit 5 ng x mg-1 protein) were undetectable in the lungs of five healthy individuals. Similarly, no XO protein could be found in the plasma samples from the right ventricle or left atrium during and after the transplantation in any of the cases. Plasma xanthine and hypoxanthine concentrations were elevated 2-10 fold immediately after the reperfusion of the transplant, indicating washout of high-energy phosphate degradation products from the ischaemic lung. Plasma uric acid decreased rather than increased immediately after the surgery and during the following 24 h. Lactoferrin was elevated during the surgery. In conclusion, these results show that XO activity in human lung is low, it is not released into the blood stream during human heart-lung transplantation, and it is unlikely to contribute to postoperative complications in these patients.
authors.affiliation: Dept of Internal Medicine, University of Helsinki, Finland.
authors.forename: V L
authors.initials: VL
authors.lastname: Kinnula
authors.forename: A
authors.initials: A
authors.lastname: Sarnesto
authors.forename: L
authors.initials: L
authors.lastname: Heikkilä
authors.forename: H
authors.initials: H
authors.lastname: Toivonen
authors.forename: S
authors.initials: S
authors.lastname: Mattila
authors.forename: K O
authors.initials: KO
authors.lastname: Raivio
mesh_terms: D002851:Chromatography, High Pressure Liquid; D004797:Enzyme-Linked Immunosorbent Assay; D005609:Free Radicals; D016041:Heart-Lung Transplantation; D006801:Humans; D019271:Hypoxanthine / Q000097:blood; D007781:Lactoferrin / Q000097:blood; D008168:Lung / Q000201:enzymology*; D016040:Lung Transplantation; D008875:Middle Aged; D011183:Postoperative Complications / Q000201:enzymology* / Q000209:etiology; D015427:Reperfusion Injury / Q000201:enzymology* / Q000209:etiology; D014527:Uric Acid / Q000097:blood; D019820:Xanthine; D014969:Xanthine Oxidase / Q000097:blood / Q000378:metabolism*; D014970:Xanthines / Q000097:blood
chemical_list: D005609:Free Radicals; D014970:Xanthines; D019820:Xanthine; D014527:Uric Acid; D019271:Hypoxanthine; D014969:Xanthine Oxidase; D007781:Lactoferrin