Prevention of lethal murine pancreas ischemia reperfusion injury is specific for tetrahydrobiopterin.
Tetrahydrobiopterin has been shown to efficiently abrogate ischemia reperfusion injury (IRI). However, it is unclear, whether its beneficial action relies on cofactor activity of one of the five known tetrahydrobiopterin-dependent reactions or on its antioxidative capacity. We therefore compared tetrahydrobiopterin with the pterin derivate tetrahydroneopterin (similar biochemical properties, but no nitric oxide synthase cofactor activity) and the antioxidants vitamin C and 5-methyltetrahydrofolate. Donor mice were pretreated with tetrahydrobiopterin, tetrahydroneopterin, vitamin C, or 5-methyltetrahydrofolate. Pancreatic grafts were subjected to 16-h cold ischemia time and implanted in syngeneic recipients. Untreated and nontransplanted animals served as controls. Following 2-h reperfusion, microcirculation was analyzed by intravital fluorescence microscopy. Graft damage was assessed by histology and nitrotyrosine immunostaining, and tetrahydrobiopterin levels were determined by HPLC. Recipient survival served as ultimate readout. Prolonged cold ischemia time resulted in microcirculatory breakdown. Only tetrahydrobiopterin pretreatment succeeded to preserve the capillary net, whereas all other compounds showed no beneficial effects. Along with increased intragraft tetrahydrobiopterin levels during recovery and implantation, only tetrahydrobiopterin pretreatment led to significant reduction of IRI-related parenchymal damage enabling recipient survival. These results show a striking superiority of tetrahydrobiopterin in preventing lethal IRI compared with related compounds and suggest nitric oxide synthases as treatment target.
Center of Operative Medicine, Department of Visceral, Transplant and Thoracic Surgery, Innsbruck Medical University, Innsbruck, Austria. manuel.maglione@i-med.ac.at
Manuel
M
Maglione
Benno
B
Cardini
Rupert
R
Oberhuber
Katrin
K
Watschinger
Marcel
M
Jenny
Johanna
J
Gostner
Martin
M
Hermann
Peter
P
Obrist
Raimund
R
Margreiter
Johann
J
Pratschke
Gerald
G
Brandacher
Ernst R
ER
Werner
D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D001205:Ascorbic Acid / Q000378:metabolism; D001708:Biopterins / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D050377:Cold Ischemia; D007150:Immunohistochemistry / Q000379:methods; D007511:Ischemia; D008099:Liver / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008833:Microcirculation; D018613:Microscopy, Confocal / Q000379:methods; D009569:Nitric Oxide / Q000737:chemistry; D009926:Organ Preservation; D010179:Pancreas / Q000473:pathology*; D016035:Pancreas Transplantation / Q000379:methods*; D015427:Reperfusion Injury / Q000517:prevention & control*; D013763:Tetrahydrofolates / Q000737:chemistry; D013997:Time Factors
D000975:Antioxidants; D013763:Tetrahydrofolates; D001708:Biopterins; C023455:tetrahydroneopterin; D009569:Nitric Oxide; C003402:sapropterin; D001205:Ascorbic Acid; C005984:5-methyltetrahydrofolate