fk-409 and Ischemia

We have demonstrated previously that preischemic treatment with FK409 [(+/-)-(E)-4-ethyl-2-[(E)-hydroxyimino]-5-nitro-3-hexenamide], a spontaneous nitric oxide (NO) donor, markedly improves ischemia/reperfusion-induced renal injury. However, there is conflicting information (renoprotective or cytotoxic) as to the contribution of NO to ischemic acute renal failure (ARF). In the present study, we investigated the effect of postischemic treatment with FK409 (1, 3, and 10 mg/kg i.v.) at 6 h after reperfusion on ischemic ARF, in comparison with the preischemic treatment effect. Ischemic ARF was induced by clamping of the left renal artery and vein for 45 min, followed by reperfusion, 2 weeks after contralateral nephrectomy. Renal function in ARF rats markedly decreased at 24 h after reperfusion. Histopathological examination of the kidney of ARF rats revealed severe renal damage. In contrast to the renoprotective effect by preischemic treatment, postischemic treatment with FK409 aggravated the ischemia/reperfusion-induced renal dysfunction and histological damage. Immunohistochemical analysis of renal sections obtained from ARF rats revealed positive staining for nitrotyrosine, a biomarker of peroxynitrite formation, in injured tubular cells, and more intense staining was observed in renal tissues from the animals that received postischemic treatment with FK409. On the other hand, the formation of nitrotyrosine, neutrophil infiltration into renal tissues, and renal superoxide production, all of which were enhanced in ARF rats, were efficiently attenuated by the preischemic treatment with FK409. These results demonstrate that, although preischemic treatment with an NO donor is renoprotective, postischemic treatment with the same agent aggravates the ischemia/reperfusion-induced renal injury, probably through peroxynitrite overproduction.

Topics: Acute Kidney Injury; Animals; Blood Urea Nitrogen; Ischemia; Kidney; Male; Neutrophil Infiltration; Nitric Oxide Donors; Nitric Oxide Synthase Type II; Nitro Compounds; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Superoxides; Time Factors; Tyrosine

Organ ischemia-reperfusion injury is caused by two consecutive steps, microcirculatory disturbance and neutrophil-endothelial cell interactions, which are caused by inflammatory cytokines. We examined the hypothesis that combination therapy with a donor (FK409) of nitric oxide, one of the potent mediators with diverse roles as a vosodilator and a platelet inhibitor, together with the cytokine suppressor agent (FR167653) attenuates warm ischemic injury in canine small bowel. Small bowel ischemia was initiated by clamping the superior mesenteric artery and vein. Animals were divided into two groups: a control group (n = 5) subjected to 2-hour small bowel ischemia only, and a combination therapy group (FK/FR group, n = 5) that received FK409 (300 mcg/kg/h) plus FR167653 (1 mg/kg/h) intravenously before and after the ischemic event. We evaluated animal survival, small bowel tissue blood flow, and enzyme release from the small bowel. All controls died from severe acidosis within 2 days and all the FK/FR animals survived 7 days (P < .05). The FK/FR group recovered more than 70% of blood flow immediately after the revascularization, while the flow was less than 40% among the controls. Serum creatine phosphokinase values in the control group after reperfusion were significantly higher than those in the FK/FR group. In conclusion improvement of the microcirculation by FK409 and inhibition of cytokine release by FR167653 together attenuated warm ischemic small bowel injury.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Dogs; Intestine, Small; Ischemia; Models, Animal; Nitric Oxide Donors; Nitro Compounds; Pyrazoles; Pyridines; Reperfusion Injury

In addition to localized tissue injury, intestinal ischaemia-reperfusion (I/R) leads to remote organ damage, in particular to the lungs. Given that nitric oxide (NO) can attenuate I/R-induced tissue injury in many situations, this study evaluated the effects of the NO donor, FK409, on leukocyte adhesion in the microcirculation of the intestinal villus and also assessed pulmonary tissue damage after intestinal I/R injury. PVG rats were subjected to 30 min intestinal ischaemia and a sub-group of animals received the NO donor FK409 (10 mg/kg; i.v.) both 30 min prior to ischaemia and 30 min post-reperfusion. The intestinal mucosal surface was visualized via an incision made in an exteriorized ileal segment and leukocyte adhesion in the villous microcirculation was determined by in vivo microscopy. Total and differential leukocyte counts from peripheral blood were evaluated. Lungs were removed at the end for histological assessment. Six out of ten untreated I/R animals failed to survive the 2 h reperfusion period, whereas all ten FK409-treated animals survived. I/R induced a significant increase in villous leukocyte adhesion of untreated I/R animals (p<0.001) and this was significantly decreased by FK409 treatment (p<0.001). The total leukocyte count was significantly decreased in untreated I/R animals (p<0.001) and this primarily resulted from a reduction in circulating neutrophil numbers. This effect was not observed in FK409-treated animals. Collapsed alveoli, thickened interstitial walls, and a dense neutrophilic infiltrate were apparent in the lungs of untreated I/R animals, whereas lung histology was normal in FK409-treated animals. In conclusion, FK409 prevented mortality, significantly reduced villous leukocyte adhesion, maintained circulating leukocyte numbers, and prevented pulmonary tissue injury following intestinal I/R. FK409 may therefore be of value in reducing both local and remote tissue damage and improving outcome in situations where intestinal I/R injury is obligatory, such as small bowel transplantation.

Topics: Animals; Blood Pressure; Cell Adhesion; Heart Rate; Intestine, Small; Ischemia; Leukocyte Count; Leukocytes; Lung; Male; Nitric Oxide Donors; Nitro Compounds; Rats; Rats, Inbred Strains; Reperfusion Injury; Survival Analysis; Vasodilator Agents

The small intestine is extremely sensitive to ischemia-reperfusion (I/R) injury and a range of microcirculatory disturbances contribute to tissue damage. Nitric oxide (NO) seems to be involved in tissue protection after I/R injury. This study therefore assessed the effects of the NO donor, FK409, on intestinal I/R injury and changes induced in intestinal microcirculation.. PVG rats were subjected to 30-min intestinal ischemia with a subgroup of animals receiving FK409 (10 mg/kg i.v.) 30 min before ischemia and 30 min postreperfusion. Controls underwent sham surgery. The mucosal surface was visualized via an incision made in an exteriorized ileal segment and FITC-BSA or acridine orange was used to quantitate macromolecular leak (MML) and leukocyte adhesion, respectively. MML from, and numbers of adherent leukocytes within, individual villi were determined every 15 min for 2 hr after removal of the vessel clamp. Heart rate and mean blood pressure (mBP) were monitored throughout the experiment.. Eleven of 12 untreated animals subjected to intestinal I/R injury failed to survive the 2 hr reperfusion period, whereas all 12 FK409-treated animals survived. MML and leukocyte adhesion were increased in untreated animals (P<0.001), and blood flow stasis eventually ensued. Although FK409 decreased mBP (P<0.001), MML and leukocyte adhesion were significantly (P<0.001) reduced, and villus blood flow was maintained throughout the observation period.. FK409 prevented mortality after intestinal I/R, significantly reduced leukocyte adhesion, and maintained blood flow after intestinal ischemia and may therefore be of value in reducing tissue damage and improving outcome after small bowel transplantation.

Topics: Animals; Blood Pressure; Capillary Permeability; Cell Adhesion; Heart Rate; Intestinal Mucosa; Intestines; Ischemia; Leukocytes; Male; Microcirculation; Microvilli; Nitric Oxide Donors; Nitro Compounds; Rats; Rats, Inbred Strains; Regional Blood Flow; Reperfusion Injury; Survival Analysis

FK409 is the first spontaneous nitric oxide (NO) donor known to increase plasma cyclic guanosine 3',5'monophosphate levels. In this study, we evaluated the effect of FK409 on pulmonary ischemia-reperfusion injury in an in situ warm ischemia canine model. Fourteen dogs were divided into two groups, and the FK409-treated group was given 5 micrograms/kg per min FK409. Warm ischemia was induced for 3 h. The arterial partial pressure of oxygen (PaO2), arterial oxygen saturation (SaO2), cardiac output (CO), left pulmonary vascular resistance (L-PVR), and endothelin-I (ET-I) were measured. A histologic study was performed, and polymorphonuclear neutrophils (PMNs) were also counted. The PaO2, SaO2, and L-PVR levels and PMNs after 30 min of reperfusion, ET-I after 2 h of reperfusion, and the 7-day survival rate were significantly (P < 0.05) better in the FK409-treated group than in the control group. The histologic damage was reduced in the FK409-treated group compared to the control group. FK409 appears to have a protective effect in ischemia-reperfusion injury of the lung.

Topics: Animals; Cardiac Output; Cyclic GMP; Dogs; Drug Evaluation, Preclinical; Endothelin-1; Ischemia; Lung; Nitric Oxide Donors; Nitro Compounds; Oxygen; Partial Pressure; Pulmonary Edema; Reperfusion Injury

ET receptor blocker (TAK-044) and NO donor (FK409) were used to improve the hepatic microcirculation following ischemia-reperfusion injury. In the first experiment (60 minutes of ischemia), 15 dogs were divided into three groups: group A (control), saline; group B, TAK 5 mg/kg; and group C, FK 0.4 mg/kg. In the second experiment (90 minutes of ischemia), 38 dogs were divided into six groups that underwent 90 minutes of hepatic ischemia followed by reperfusion: group I (control), saline only; group II, TAK 5 mg/kg and FK 3.2 mg/kg; group III, TAK 5 mg/kg and FK 0.4 mg/kg; group IV, TAK 5 mg/kg; group V, FK 0.4 mg/kg; and group VI, FK3.2 mg/kg. All drugs were administered through the portal vein. Following 60 minutes of ischemia, both FK and TAK produced significant improvement in hepatic microcirculation and enzymatic status when compared with the control group. After 90 minutes of ischemia, low doses of FK and TAK significantly improved hepatic microcirculation and reduced portal pressure following reperfusion in group III compared with group I. Leakage of hepatic enzymes was prevented and tissue injury score was significantly lower in group III. In group VI, early protection was obtained to some extent; however, blood pressure was reduced significantly following reperfusion compared with group I. In contrast, hepatocellular function deteriorated and the tissue injury score was higher in group II animals. TAK pretreatment with low doses of FK provided the best protection for the hepatic microcirculation in ischemia-reperfusion injury of the liver.

Topics: Animals; Blood Pressure; Creatine Kinase; Dogs; Endothelins; Female; Ischemia; Isoenzymes; Liver; Liver Circulation; Male; Microcirculation; Nitric Oxide; Nitro Compounds; Peptides, Cyclic; Reperfusion Injury