oxalylglycine and Reperfusion-Injury

Hypoxia-inducible factor-1α (HIF-1α) plays a key role in angiogenesis, improves flap survival, and activates autophagy. The effect of HIF-1α-induced autophagy is still debatable. Thus, we investigated the effect of HIF-1α-induced autophagy on multiterritory perforator flap survival. In this study, 99 male Sprague-Dawley rats received multiterritory perforator flap procedure and were divided into three groups with 33 each. The dimethyloxalylglycine (DMOG) plus 3-methyladenine (3-MA) group received intraperitoneal injection of DMOG (40 mg/kg) and 3-MA (10 mg/kg). The DMOG group and control group received comparative DMOG and saline respectively. On postoperative day (POD) 7, HIF-1α's activities of flap survival and perfusion improvement were confirmed in DMOG group, however, its positive effects were further enhanced by co-administration of autophagy inhibitor, 3-MA. On POD 1, vascular endothelial growth factor, mean microvascular density and blood perfusion were not affected by HIF-1α up-regulation or autophagy inactivation. However, HIF-1α-induced autophagy augments apoptosis and oxidative stress. The increased level of apoptosis and oxidative stress was reversed by 3-MA and resulted in further flap survival improvement. In conclusion, HIF-1α-induced autophagy has a detrimental effect on multiterritory perforator flap survival and the flap survival was determined by the combined effects of ischemia and reperfusion injury.

Topics: Adenine; Amino Acids, Dicarboxylic; Animals; Autophagy; Hypoxia-Inducible Factor 1, alpha Subunit; Male; Perforator Flap; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Up-Regulation

Hypoxia inducible factor (HIF)-1 pathway signalling has a protective effect against ischemia/reperfusion injury. The prolyl-hydroxylase inhibitor dimethyloxalylglycine (DMOG) activates the HIF-1 pathway by stabilizing HIF-1α. In a rat model of brain death (BD)-associated donor heart dysfunction we tested the hypothesis that pre-treatment of brain-dead donors with DMOG would result in a better graft heart condition.. BD was induced in anesthetized Lewis rats by inflating a subdurally placed balloon catheter. Controls underwent sham operations. Then, rats were injected with an intravenous dose of DMOG (30 mg/kg) or an equal volume of physiologic saline. After 5 hours of BD or sham operation, hearts were perfused with a cold (4°C) preservation solution (Custodiol; Dr. Franz Köhler Chemie GmbH; Germany), explanted, stored at 4°C in Custodiol, and heterotopically transplanted. Graft function was evaluated 1.5 hours after transplantation.. Compared with control, BD was associated with decreased left ventricular systolic and diastolic function. DMOG treatment after BD improved contractility (end-systolic pressure volume relationship E'max: 3.7 ± 0.6 vs 3.1 ± 0.5 mm Hg/µ1; p < 0.05) and left ventricular stiffness (end-diastolic pressure volume relationship: 0.13 ± 0.03 vs 0.31 ± 0.06 mm Hg/µ1; p < 0.05) 5 hours later compared with the brain-dead group. After heart transplantation, DMOG treatment of brain-dead donors significantly improved the altered systolic function and decreased inflammatory infiltration, cardiomyocyte necrosis, and DNA strand breakage. In addition, compared with the brain-dead group, DMOG treatment moderated the pro-apoptotic changes in the gene and protein expression.. In a rat model of potential brain-dead heart donors, pre-treatment with DMOG resulted in improved early recovery of graft function after transplantation. These results support the hypothesis that activation of the HIF-1 pathway has a protective role against BD-associated cardiac dysfunction.

Topics: Amino Acids, Dicarboxylic; Animals; Brain; Disease Models, Animal; Heart Transplantation; Male; Rats; Rats, Inbred Lew; Reperfusion Injury; Tissue Donors; Ventricular Function, Left

The revascularization therapy of pulmonary embolism is associated with ischemia-reperfusion (IR) injury. However, the effect of IR injury on pulmonary arterial endothelial function has not been elucidated. Male Sprague-Dawley rats were divided into a control, an IR and an IR plus hypoxia-inducible factor 1 alpha (HIF-1α) stabilizer DMOG group. We found that the acetylcholine (ACh)-induced relaxation was dramatically reduced in pulmonary arteries from IR-injured rats compared with controls (P < 0.01). Interestingly, pre-treatment with the DMOG significantly improved ACh-stimulated pulmonary arterial dilatation (P < 0.01). The protein expression of HIF-1α in pulmonary artery was significantly down-regulated by IR injury (P < 0.01). Moreover, DMOG remarkably reversed IR-induced down-regulation of HIF-1α (P < 0.01). There was no difference in ACh-stimulated relaxation of endothelium-denuded or L-NMMA-treated pulmonary arteries among the three groups. The bioavailability of nitric oxide (NO) and the phosphorylation level of inducible NO synthase (iNOS) in pulmonary artery were significantly decreased by IR injury (both P < 0.01), which were reversed by DMOG (P < 0.05 or P < 0.01). In addition, the levels of superoxide in pulmonary artery were not affected by the IR injury as well as IR injury plus administration with DMOG. The present study demonstrated that HIF-1α contributes to pulmonary vascular dysfunction in lung IR injury.

Topics: Amino Acids, Dicarboxylic; Animals; Blotting, Western; Disease Models, Animal; Endothelium, Vascular; Hypertension, Pulmonary; Hypoxia-Inducible Factor 1, alpha Subunit; Male; Pulmonary Artery; Pulmonary Embolism; Rats; Rats, Sprague-Dawley; Reperfusion Injury

Storage protocols of vascular grafts need further improvement against ischemia-reperfusion (IR) injury. Hypoxia elicits a variety of complex cellular responses by altering the activity of many signaling pathways, such as the oxygen-dependent prolyl-hyroxylase domain-containing enzyme (PHD). Reduction of PHD activity during hypoxia leads to stabilization and accumulation of hypoxia inducible factor (HIF) 1α. We examined the effects of PHD inhibiton by dimethyloxalylglycine on the vasomotor responses of isolated rat aorta and aortic vascular smooth muscle cells (VSMCs) in a model of cold ischemia/warm reperfusion. Aortic segments underwent 24 hours of cold ischemic preservation in saline or DMOG (dimethyloxalylglycine)-supplemented saline solution. We investigated endothelium-dependent and -independent vasorelaxations. To simulate IR injury, hypochlorite (NaOCl) was added during warm reperfusion. VSMCs were incubated in NaCl or DMOG solution at 4°C for 24 hours after the medium was changed for a supplied standard medium at 37°C for 6 hours. Apoptosis was assessed using the TUNEL method. Gene expression analysis was performed using quantitative real-time polymerase chain reaction. Cold ischemic preservation and NaOCl induced severe endothelial dysfunction, which was significantly improved by DMOG supplementation (maximal relaxation of aortic segments to acetylcholine: control 95% ± 1% versus NaOCl 44% ± 4% versus DMOG 68% ± 5%). Number of TUNEL-positive cell nuclei was significantly higher in the NaOCl group, and DMOG treatment significantly decreased apoptosis. Inducible heme-oxygenase 1 mRNA expressions were significantly higher in the DMOG group. Pharmacological modulation of oxygen sensing system by DMOG in an in vitro model of vascular IR effectively preserved endothelial function. Inhibition of PHDs could therefore be a new therapeutic avenue for protecting endothelium and vascular muscle cells against IR injury.

Topics: Amino Acids, Dicarboxylic; Animals; Aorta; Apoptosis; Cell Culture Techniques; Disease Models, Animal; Endothelium, Vascular; Enzyme Inhibitors; Heme Oxygenase-1; Hypoxia-Inducible Factor 1, alpha Subunit; In Situ Nick-End Labeling; Isometric Contraction; Male; Muscle, Smooth, Vascular; Procollagen-Proline Dioxygenase; Rats; Rats, Sprague-Dawley; Reperfusion Injury; RNA, Messenger; Vasodilation

Intestinal ischemia/reperfusion injury (IR) is characterized by intermittent loss of perfusion to the gut, resulting in dramatic increases in morbidity and mortality. Based on previous studies indicating an anti-inflammatory role for hypoxia-inducible factor (HIF)-1-elicited enhancement of extracellular adenosine production via ecto-5'-nucleotidase (CD73) and signaling through the A2B adenosine receptor (A2BAR), we targeted HIF-1 during IR using pharmacological or genetic approaches. Initial studies with pharmacological HIF activation indicated attenuation of intestinal injury with dimethyloxallyl glycine (DMOG) treatment during murine IR. Although DMOG treatment was associated with induction of CD73 transcript and protein, DMOG protection was abolished in cd73(-/-) mice. Similarly, DMOG treatment enhanced A2BAR transcript and protein levels, whereas DMOG protection was abolished in A2BAR(-/-) mice. Finally, studies of mice with conditional HIF-1α deletion in intestinal epithelia or pharmacological inhibition of HIF-1 with 17-(dimethylaminoethylamino)-17-demethoxygeldanamycin revealed enhanced tissue injury during IR. These studies indicated a tissue-protective role of HIF-dependent enhancement of intestinal adenosine generation and signaling during intestinal IR.

Topics: 5'-Nucleotidase; Amino Acids, Dicarboxylic; Animals; Colitis; Glycine; Hypoxia-Inducible Factor 1, alpha Subunit; Intestinal Mucosa; Mice; Mice, Inbred C57BL; Mice, Knockout; Mice, Transgenic; Receptor, Adenosine A2B; Reperfusion Injury; RNA, Messenger; Signal Transduction

Hypoxia-inducible factor-1 (HIF-1) could ameliorate renal ischemia reperfusion injury (IRI), but the underlying mechanism remains elusive. In the current study, we aim to investigate the possible role of prolyl hydroxylases inhibitor dimethyloxalylglycine (DMOG) in inducing delayed preconditioning-like effects against IRI. Mice were divided into four groups (n = 6): sham group; IRI group; DMOG group: pretreated with DMOG 24 h before IRI; and GW274150 + DMOG group: pretreated with DMOG followed by iNOS inhibitor GW274150 treatment 24 h before IRI. The results showed that the protein level of HIF-1a and the expression of its targets inducible nitric oxide synthase (iNOS), erythropoietin, and heme oxygenase-1 were obviously increased after administration of DMOG. Histological analysis of renal function showed improvement in tubulointerstitial injury due to ischemia by delayed preconditioning with DMOG. GW274150 antagonized the delayed renal protection afforded by DMOG as reflected by deteriorated renal dysfunction, aggravated histological injury, increased renal cell apoptosis, and increased vimentin expression in the kidney. In conclusion, our data demonstrate that DMOG pretreatment induces delayed renal protection against IRI in mice and the beneficial effects are mitigated by pharmacological inhibition of iNOS, suggesting that the protective effects derived from HIF-1 activation via DMOG in the kidney are partially mediated by iNOS.

Topics: Amino Acids, Dicarboxylic; Animals; Apoptosis; Creatinine; Hypoxia-Inducible Factor 1; Kidney; Male; Mice; Mice, Inbred C57BL; Nitric Oxide Synthase Type II; Protective Agents; Protein Stability; Reperfusion Injury; Sulfides; Vimentin