Effect of nitric oxide in ischemia/reperfusion of the pancreas

BACKGROUND: Ischemia/reperfusion injury, and thus graft pancreatitis, remains a major problem in pancreas transplantation. Contradictory results about the role of nitric oxide (NO) in pancreatic ischemia/reperfusion have been reported; however, in none of the reports has a detailed comparison between inhibition of NO synthase and NO supplementation been carried out. METHODS: Vascular isolation of the pancreatic tail was performed in landrace pigs. After splenectomy catheters placed in the distal part of the splenic vessels allowed collection of the venous effluent and perfusion of the pancreatic tail. Three hours of complete warm ischemia was followed by 6 h of reperfusion. The effect of the NO donor sodium nitroprusside (SNP) and L-arginine was compared to a control group and NO synthase inhibition with L-NAME. RESULTS: Lipase in the venous effluent of the pancreas was significantly decreased in the SNP and the L-arginine groups. Vascular resistance was markedly elevated in the L-NAME group and reduced in the NO donor groups. Tissue pO2 after reperfusion was only significantly elevated in the SNP group. Granulocyte infiltration and also overall histological tissue injury were most severe in the control group followed by the L-NAME group, the SNP group, and the L-ARG group. CONCLUSION: The data show that supplementation of nitric oxide is clearly protective in pancreatic ischemia/reperfusion. However, inhibition of NO synthesis does not lead to an equally clear aggravation of tissue injury.     

Promising effects of ischemic preconditioning in renal transplantation

BACKGROUND: Ischemic preconditioning, a phenomenon induced by brief ischemia and reperfusion periods, renders an organ tolerant to subsequent prolonged ischemia. This study evaluated different schedules of preconditioning the kidney to assess the role of nitric oxide (NO) and determine the effects of preconditioning on kidney transplantation. METHODS: In study design A, to determine the optimum procedure of preconditioning, one-cycle schedules were assayed by occluding/releasing renal pedicles according to various warm ischemic (5, 10, 15, 20 min) and reperfusion (10, 20, 40 min) windows in Sprague-Dawley rats. Thereafter, warm renal ischemia was induced by clamping both pedicles for 40 minutes. Design B used the most suitable schedule found from the first study to obtain several groups, using either a direct nitric oxide donor (spermine NONOate) or two nitric oxide synthase (NOS) blockers (L-NAME and aminoguanidine), to determine whether NO mediates in renal preconditioning. To establish whether preconditioning reduces cold preservation damage, in Design C the optimum preconditioning schedule was used in syngeneic Lewis rats where preconditioned and non-preconditioned kidneys were transplanted after five hours of cold storage in Euro-Collins solution. RESULTS: The best preconditioning schedule consisted of 15 minutes of warm ischemia and 10 minutes of reperfusion (Prec 15/10), since it was the only schedule that offered both functional and histological protection. The NO donor reproduced the ischemic preconditioning. Non-selective NOS blockade abolished the preconditioning and exacerbated ischemic damage, which was overcome by the addition of the NO donor. Selective blocking of inducible NOS also abolished the effects of preconditioning. Renal NO increased at the end of preconditioning in the Prec 15/10 group. Prolongation of the reperfusion window (20 or 40 min) abolished the preconditioning protection, although it was associated with a further increase in renal NO. As renal DNA oxidative injury paralleled NO, increasing with prolongation of reperfusion, it may account for the disappearance of preconditioning. Finally, the one-cycle preconditioning schedule offered an effective functional and histological protection against cold preservation damage in rat renal transplantation. CONCLUSIONS: Fifteen minutes of warm ischemia and 10 minutes of reperfusion in the kidney is the most suitable one-cycle schedule for preconditioning since it protects from both warm and cold ischemia. The beneficial effect of preconditioning is related to the local production of NO, and we believe it has promising therapeutic value in clinical renal transplantation.     

Interaction of eicosanoids and nitric oxide in renal reperfusion injury.

BACKGROUND: Both the eicosanoids and nitric oxide are known to play an important role in the pathogenesis of postischemic injury. Recent evidence has suggested that the generation of each may affect the other via a feedback loop. This was investigated in an experimental model of renal warm ischemia reperfusion injury. METHODS: Rats underwent bilateral renal warm ischemia (15-60 min) then reperfusion (20 or 80 min) followed by a unilateral nephrectomy to measure renal nitric oxide (as nitroxides) and eicosanoids. Renal function was measured on days 2 and 7 prior to terminal nephrectomy for tissue analysis. RESULTS: Vasodilator eicosanoids (6-KPGF1alpha and PGE2) fell on reperfusion in line with the duration of warm ischemia with a concomitant rise in the vasoconstrictor TxA2. The ratio of vasodilator to vasoconstrictor eicosanoids fell from 8.22 (2.3) in the control to 0.82 (0.1) in the 60-min warm ischemia group (P<0.01). Renal levels of nitroxides rose on reperfusion demonstrating an inverse correlation with the eicosanoid ratio (r2=0.86). Renal function was impaired at both day 2 and day 7 and showed a positive correlation with the eicosanoid ratio (r2=0.67 and 0.62, respectively). CONCLUSIONS: Renal warm ischemic injury is associated with a progressive fall in the ratio of vasodilator-to-vasoconstrictor eicosanoids from early in reperfusion through to day seven although nitric oxide was elevated throughout the same period. There was no evidence of coinduction of nitric oxide synthase and cyclooxygenase in this model.     

Protective effects of inhaled nitric oxide and gabexate mesilate in lung reperfusion injury after transplantation from non-heart-beat donors.

BACKGROUND: The use of lung grafts from non-heart-beat donors (NHBDs) is one way of solving the critical donor organ shortage. Inhaled nitric oxide (NO) and gabexate mesilate (FOY), a protease inhibitor, can attenuate some types of neutrophil-mediated tissue injury. Using an isolated lung ventilation and perfusion model, we studied the effects of these agents on reperfusion injury following lung transplantation from NHBDs. METHODS: Five groups of minipigs were studied. In group 1(n = 6), the lungs were flushed and harvested after cardiac arrest, and were reperfused for 2 hours after 2 hours of cold ischemia. In group 2 (n = 6), the lungs were harvested after 2 hours of in situ warm ischemia, followed by 2 hours of cold ischemia and 2 hours of reperfusion. In groups 3 (n = 7), 4 (n = 7), and 5 (n = 6), the procedure was the same as in group 2, except in group 3, NO was inhaled before and after ischemia, in group 4, FOY was given intravenously, and in group 5, a combination of inhaled NO and intravenous FOY were administered. RESULTS: Compared with group 1, group 2 had higher mean pulmonary arterial pressure, vascular resistance, and lower arterial blood oxygen tension. Furthermore, these negative effects of warm ischemia were also reflected in the contents of bronchoalveolar lavage fluid, tissue myeloperoxidase (MPO) activity, histology, and permeability change. Either FOY or NO administration (groups 3 or 4) ameliorated the associated injury. A combination of FOY and NO use (group5) decreased the parameters of lung reperfusion injury measurement to a larger degree than either agent individually. CONCLUSIONS: The inhaled NO and FOY can protect NHBD lung grafts at an early reperfusion period. Their use in combination has an additive protective effect that might be applied to the protection of NHBD grafts from preservation and reperfusion injury.     

Attenuation of renal ischemia/reperfusion injury by a triple drug combination therapy

BACKGROUND: Renal ischemia is of great clinical interest because of its role in renal failure and renal graft rejection. The purpose of this study was to investigate the therapeutic effects of a combination therapy of: n-acetyl cysteine (NAC), a potent antioxidant, sodium nitroprusside (SNP), a nitric oxide donor and phosphormidon (P), an endothelin-1 converting enzyme inhibitor, on tissue protection against renal ischemia/reperfusion injury in the canine model. METHODS: In this study, 15-20 kg male dogs were subjected to 90 minutes of warm unilateral renal ischemia after removal of one kidney and then divided into control, ischemia alone and treatment groups. Blood samples were collected from these dogs for measurement of kidney function tests and the kidneys were harvested at different time intervals for morphological evaluation, immunostaining and Tunnel Assay. RESULTS: Kidney function tests (serum creatinine and blood urea nitrogen [BUN]) showed a significant difference between untreated and treated groups. ** P <0.01, * P< 0.0001 for treated versus untreated. The protective effect of the combination therapy is also supported by light microscopic studies, immunostaining of renal tissue sections for pro-inflammatory cytokines (TNF-alpha and IFN-gamma), iNOS, and apoptosis by TUNEL assay. CONCLUSIONS: Our results suggest that pre-administration of a combination of NAC, SNP, and P attenuates renal ischemia/reperfusion injury. This has potential application in preservation of donor kidney for transplantation by protecting cells against free radical damage.     

Continuous infusion of nitroglycerin improves pulmonary graft function of non-heart-beating donor lungs

BACKGROUND: The warm ischemic period of lungs harvested from a non-heart-beating donor (NHBD) results in an increased ischemia-reperfusion injury after transplantation. The intravenous application of nitroglycerin (NTG), a nitric oxide (NO) donor, proved to be beneficial during reperfusion of lung grafts from heart-beating donors. The objective of the present study was to investigate the effect of nitroglycerin on ischemia-reperfusion injury after transplantation of long-term preserved NHBD-lungs. METHODS: Sixteen pigs (body weight, 20-30 kg) underwent left lung transplantation. In the control group (n=5), lungs were flushed (Perfadex, 60 mL/kg) and harvested immediately after cardiac arrest. In the NHBD group (n=5) and the NHBD-NTG group (n=6), lungs were flushed 90 min (warm ischemia) after cardiac arrest. After a total ischemia time of 19 hr, lungs were reperfused and graft function was observed for 5 hr. Recipient animals in the NHBD-NTG group received 2 microg/kg/min of NTG administered intravenously during the observation period starting 5 min before reperfusion. Tissue specimens and bronchoalveolar lavage fluid (BALF) were obtained at the end of the observation period. RESULTS: Compared with the control group, pulmonary gas exchange was significantly impaired in the NHBD group, whereas graft function in the NHBD-NTG group did not change. Leukocyte fraction and protein concentration in the BALF and histologic alteration of the NHBD-NTG group were not different from controls. CONCLUSIONS: Continuous infusion of NTG in the early reperfusion period improves pulmonary graft function of NHBD lungs after long-term preservation. The administration of an NO donor during reperfusion may favor the use of NHBD lungs to alleviate the critical organ shortage in lung transplantation.     

Initiation of microvascular protection by nitric oxide in late preconditioning

The authors hypothesized that nitric oxide is induced by a brief period of ischemia/reperfusion (ischemic preconditioning, IPC) on postoperative day (POD) 1, and that this released nitric oxide is responsible for initiating a delayed microvascular protection against a prolonged period of ischemia in skeletal muscle on POD day 2. The cremaster muscle of male Sprague-Dawley rats underwent 4 hr of ischemia, and then 60 min of reperfusion. IPC consisted of 45 min of ischemia but was done 24 hr before the prolonged ischemia. Local intraarterial infusion of sodium nitroprusside (SNP, a donor of nitric oxide) or Nw-nitro-L-arginine (L-NA, a nonselective nitric oxide synthase antagonist) were also given 24 hr before prolonged ischemia. Arteriole diameters and capillary perfusion were measured using intravital microscopy. Four groups were compared: 1) control; 2) IPC; 3) SNP + sham IPC; and 4) L-NA + IPC. Four hours of ischemia followed by reperfusion created a significant vasoconstriction and capillary no-reflow in the microcirculation of cremaster muscles. These alterations were largely prevented by IPC. Local intraarterial infusion of SNP without IPC created a similar microvascular protection to that induced by IPC alone. In contrast, intraarterial infusion of L-NA prior to IPC eliminated the IPC-induced microvascular protection. In conclusion, in late preconditioning, nitric oxide contributes to the initiation of a delayed microvascular protection against prolonged ischemia in skeletal muscle.     

Effects of tetrahydrobiopterin on endothelial dysfunction in rats with ischemic acute renal failure

The role of nitric oxide (NO) in ischemic renal injury is still controversial. NO release was measured in rat kidneys subjected to ischemia and reperfusion to determine whether (6R)-5,6,7,8-tetrahydro-L-biopterin (BH4), a cofactor of NO synthase (NOS), reduces ischemic injury. Twenty-four hours after bilateral renal arterial clamp for 45 min, acetylcholine-induced vasorelaxation and NO release were reduced and renal excretory function was impaired in Wistar rats. Administration of BH4 (20 mg/kg, by mouth) before clamping resulted in a marked improvement of those parameters (10(-8) M acetylcholine, delta renal perfusion pressure: sham-operated control -45 +/- 5, ischemia -30 +/- 2, ischemia + BH4 -43 +/- 4%; delta NO: control +30 +/- 6, ischemia + 10 +/- 2, ischemia + BH4 +23 +/- 4 fmol/min per g kidney; serum creatinine: control 23 +/- 2, ischemia 150 +/- 27, ischemia + BH4 48 +/- 6 microM; mean +/- SEM). Most of renal NOS activity was calcium-dependent, and its activity decreased in the ischemic kidney. However, it was restored by BH4 (control 5.0 +/- 0.9, ischemia 2.2 +/- 0.4, ischemia + BH4 4.3 +/- 1.2 pmol/min per mg protein). Immunoblot after low-temperature sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that the dimeric form of endothelial NOS decreased in the ischemic kidney and that it was restored by BH4. These results suggest that the decreased activity of endothelium-derived NO may worsen the ischemic tissue injury, in which depletion of BH4 may be involved.     

Propofol attenuates intestinal mucosa injury induced by intestinal ischemia-reperfusion in the rat

PURPOSE: We investigated whether propofol at a sedative dose can prevent intestinal mucosa ischemia/reperfusion (I/R) injury, and if propofol can attenuate oxidative stress and increases in nitric oxide (NO) and endothelin-1 (ET-1) release that may occur during intestinal I/R injury. METHODS: Rats were randomly allocated into one of five groups (n=10 each): (i) sham control; (ii) injury (one hour superior mesenteric artery occlusion followed by three hours reperfusion); (iii) propofol pre-treatment, with propofol given 30 min before inducing intestinal ischemia; (iv) simultaneous propofol treatment, with propofol given 30 min before intestinal reperfusion was started; (v) propofol post-treatment, with propofol given 30 min after intestinal reperfusion was initiated. In the treatment groups, propofol 50 mg x kg(-1) was administrated intraperitoneally. Animals in the control and untreated injury groups received equal volumes of intralipid (the vehicle solution of propofol) intraperitoneally. Intestinal mucosa histology was analyzed by Chiu's scoring assessment. Levels of lactic acid (LD), NO, ET-1, lipid peroxidation product malondialdehyde (MDA) and superoxide dismutase (SOD) activity in intestinal mucosa were determined. RESULTS: Histological results showed severe damage in the intestinal mucosa of the injury group accompanied by increases in MDA, NO and ET-1 and a decrease in SOD activity. Propofol treatments, especially pre-treatment, significantly reduced Chiu's scores and levels of MDA, NO, ET-1 and LD, while restoring SOD activity. CONCLUSION: These findings indicate that propofol attenuates intestinal I/R-induced mucosal injury in an animal model. The response may be attributable to propofol's antioxidant properties, and the effects of inhibiting over-production of NO and in decreasing ET-1 levels.     

Ablation of free radical-mediated reperfusion injury for the salvage of kidneys taken from non-heartbeating donors. A quantitative evaluation of the proportion of injury caused by reperfusion following periods of warm, cold, and combined warm and cold ischemia

Postischemic renal failure is a severe problem following cadaveric renal transplantation, especially if the kidney has been harvested from a non-heartbeating donor, and thereby subjected to periods of both warm and cold ischemia. It is well established that a substantial component of postischemic injury is produced by oxygen-derived free radicals generated from xanthine oxidase at reperfusion. However, the clinical potential of free radical ablative therapy is dependent upon the proportion of the total injury caused by this reperfusion mechanism, compared with the proportion resulting from ischemic injury per se. Therefore, we quantitatively evaluated these proportions in porcine kidneys subjected to various periods of warm (renal artery occlusion in situ), cold (harvest, cold preservation, and allotransplantation), and combined warm and cold ischemia. Experiments were paired, one kidney treated with either superoxide dismutase (SOD) or allopurinol for free radical ablation, the contralateral kidney serving as a control. Creatinine clearance (Ccr) was measured separately for each kidney 48 hr after reperfusion. After 1 and 2 hr of warm ischemia, Ccr dropped to 50% and 36% of normal, respectively. This was improved to 110% and 55% when SOD was given into the renal artery at reperfusion. Similarly, after 24 and 48 hr of cold ischemia, kidney function was significantly improved from 30% and 18% to 72% and 47% of normal, respectively, when allopurinol was added to the preservation solution. SOD used at harvest and again at reperfusion was particularly effective following combined warm and cold ischemia, in a situation mimicking the harvest of cadaver kidneys from a non-heartbeating donor. These findings suggest that the ablation of free radical-mediated reperfusion injury may improve posttransplant renal function sufficiently to allow expansion of the cadaveric donor pool to include non-heartbeating donors.     

Role of nitric oxide in resveratrol-induced renal protective effects of ischemic preconditioning

BACKGROUND: Resveratrol, a natural antioxidant and polyphenol found in red wine and grapes, has been found to pharmacologically precondition the heart through upregulation of nitric oxide (NO). This study was designed to explore the involvement of NO in the renoprotective effect of resveratrol in renal ischemic preconditioning in rat kidney. METHODS: Ischemic preconditioning was induced by three cycles 2-minutes of ischemia followed by 5 minutes of reperfusion before 45 minutes of prolonged ischemia. Resveratrol was given 1 hour before the surgical procedures. RESULTS: Ischemic preconditioning and resveratrol treatment significantly improved the renal dysfunction, decrease in total NO levels, and oxidative stress induced by 45 minutes of ischemia followed by 24 hours of reperfusion. Histopatholgic examination of the kidneys of ischemic/reperfusion rats revealed severe renal damage, which was attenuated in both preconditioned and resveratrol-treated animals. Preconditioning and resveratrol administration led to a marked increase in NO levels in kidney. Renoprotective effects of resveratrol were abolished when animals were pretreated with NG-nitro-L-arginine methyl ester, a nonspecific NO synthase inhibitor. CONCLUSIONS: These findings demonstrate an important contributory role of NO in the protection afforded by resveratrol in renal ischemic preconditioning. CLINICAL RELEVANCE: It is now well established that brief periods of ischemia followed by reperfusion render a variety of tissues tolerant to subsequent ischemia/reperfusion-induced injury. This phenomenon, referred to as ischemic preconditioning, was first demonstrated in the dog myocardium. The potential for clinical application of such a powerful protective phenomenon has generated enormous interest in identifying the underlying intracellular signaling pathways, with the ultimate aim of pharmacologically exploiting these mechanisms to develop therapeutic strategies that can enhance tolerance to ischemia/reperfusion injury in patients. This study explored the possible involvement of nitric oxide in renal ischemic preconditioning.     

Nitric oxide in acute renal failure: NOS versus NOS

This overview provides information on the pathophysiology of the inducible nitric oxide synthase/nitric oxide (iNOS/NO) system in the injury to cultured renal tubular epithelia, freshly isolated proximal tubules, and the whole organ after hypoxic or ischemic insult. The findings emphasize the role of concomitant oxidative and nitrosative stress and the role of peroxynitrite in the ensuing renal dysfunction. Scavenging peroxynitrite using seleno-organic compounds like ebselen provides renoprotection against ischemic injury. These sequelae of renal ischemia are a result of endothelial dysfunction, which is most probably responsible for the "no-reflow" phenomenon and further aggravation of tubular ischemia during the early reperfusion period. Recent studies have demonstrated that transplantation of functional endothelial cells into ischemic kidney provided a dramatic renoprotective effect. In conclusion, the intricate relations between endothelial and epithelial cells, based in part on the relations between endothelial and inducible nitric oxide synthases, are perturbed in renal ischemia primarily as a result of endothelial dysfunction precipitating epithelial injury.     

Nebivolol reduces experimentally induced warm renal ischemia reperfusion injury in rats

Ischemia/reperfusion injury, which is commonly seen in the field of renal surgery or transplantation, is a major cause of acute renal failure. The objective of the present study was to examine the role of nebivolol in modulating peroxynitrite species-induced inflammation and apoptosis after renal warm ischemia/reperfusion injury in rats. The present study was designed to investigate the effects of nebivolol on the renal warm ischemia/reperfusion injury in rats treated with the nitric oxide synthase inhibitor, N(omega)-nitro-L-arginine methyl ester. After right nephrectomy, nebivolol was administered for 15 days. On the 16(th) day, ischemia was induced in contra lateral kidney for 45 min, followed by reperfusion for 24 hr. Renal function, inflammation, and apoptosis were estimated at the end of 24 hr reperfusion. Nebivolol improved the renal dysfunction and reduced inflammation and apoptosis after renal ischemia/reperfusion injury. In conclusion, nebivolol shows potent anti-apoptotic and anti-inflammatory properties due to its NO-releasing property. These findings may have major implications in the treatment of human ischemic acute renal failure.     

Short-term inhaled nitric oxide in canine lung transplantation from non-heart-beating donor

BACKGROUND: Use of lungs harvested from non-heart-beating donors (NHBDs) would increase the pulmonary donor pool; however, this strategy would have higher risk of early postoperative graft dysfunction due to unavoidable warm ischemic time. We evaluated the effects of short-term inhaled nitric oxide (NO) during reperfusion in canine left single-lung allotransplantation from a non-heart-beating donor. METHODS: The donor dogs were sacrificed without heparinization and left at room temperature for 3 hours. Then, recipient dogs received a left single-lung allotransplantation. After implantation, the right bronchus and pulmonary artery were ligated. In group 1 (n = 6), NO gas was administered continuously at a concentration of 40 parts per million throughout a 6-hour assessment period. In group 2 (n = 6), NO gas was administered for the initial 1 hour during reperfusion. In group 3 (n = 6), nitrogen gas was administered for control. RESULTS: Groups treated with NO exhibited lower pulmonary vascular resistance, as well as improved survival and oxygenation. There was no significant difference in these parameters between group 1 and group 2. Myeloperoxidase activity was significantly lower in NO-treated groups. CONCLUSIONS: Inhaled NO during reperfusion is beneficial in lung transplantation from non-heart beating donors. The beneficial effect is obtained mainly during the first hour of reperfusion.     

缺血预处理对大鼠小体积供肝的保护作用及机制

目的探讨缺血预处理（IPC）对大鼠小体积供肝的保护作用及其机制。方法120只SD大鼠随机分为3组（每组20对）：无热缺血组（NWI）、缺血再灌注组（WI）和缺血预处理组（IPC）。用双袖套法建立大鼠小体积肝移植模型。各组10只受体大鼠于术前1d、术后1、2、3、5d取血，用自动生化分析仪检测AST和ALT。NWI组于供肝灌注前及植入后0．5、1、2、3h，WI组于热缺血前及植入后0．5、1、2、3h，IPC组于IPC前、IPC后及植入后0．5、1、2、3h取肝组织，用硝酸还原法检测其NO浓度。结果IPC可降低大鼠小体积肝移植术后血清AST和ALT浓度，提高再灌注早期肝脏组织NO的浓度，降低再灌注晚期肝脏组织NO的浓度（P〈0．05）。结论NO在大鼠肝脏的缺血再灌注损伤中可能具有双重作用。IPC对大鼠小体积供肝的缺血再灌注损伤有保护作用。其机制可能是通过促进供肝再灌注后早期NO合成，改善肝脏微循环，同时抑制供肝再灌注后晚期NO合成，减轻过量NO的损伤作用，从而保护移植肝脏功能。     

Exogenous nitric oxide downregulates MIP-2 and MIP-1alpha chemokines and MAPK p44/42 after ischemia and reperfusion of the rat kidney.

The mechanisms by which nitric oxide (NO) exerts its protective effect in the ischemia/reperfusion (I/R) injury of the kidney have not been fully determined. The hypothesis of this study was based on the assumption that I/R upregulates some chemokines (MIP-2 and MIP-1alpha) as well as certain protein kinases (MAPK p44/42), and therefore we aimed in this work at recognizing if an exogenous NO donor would downregulate these effects in rat ischemic kidneys at the same time that it would offer functional protection as measured by serum creatinine. Sprague-Dawley rats were subjected to renal warm ischemia (75 min) and contralateral nephrectomy. Animals were divided into 3 groups (n = 8 per group): sham, ischemic control, and ischemic group treated with sodium nitroprusside (NaNP 5 mg/kg) given 15 min prior to reperfusion. Serum creatinine (SCr), serum chemokines (MIP-2 and MIP-1alpha), kidney tissue MAPK p44/42, kidney neutrophil infiltration determined by myeloperoxidase (MPO), and light histology were evaluated 4 h after reperfusion began. There were significant improvements in SCr and better histopathological features in the I/R-NaNP group compared with the I/R group. Similarly, the I/R-NaNP kidneys exhibited a downregulating effect of serum chemokines (MIP-2 and MIP-1alpha) and kidney tissue MAPK p44/42 that was not observed in the I/R group alone. The MPO levels were lower in the I/R-NaNP group compared with the I/R untreated group. We can conclude from these experiments that I/R of the rat kidney upregulated the production of MIP-2 and MIP-1alpha chemokines and the activation of MAPKp44/42. It also had a detrimental effect on the function and structure of the ischemic kidney. Exogenous NO had a temporal protective effect in organ function and histology and exerted a downregulating response in the production of MIP-2 and MIP-1alpha chemokines and the activation of MAPK p44/42 following I/R.     

一氧化氮供体防治急性缺血性肾衰的实验研究

为了进一步证实一氧化氮（ＮＯ）在急性缺血性肾衰（ＩＡＲＦ）发生发展中的作用，采用ＮＯ供体ＳＩＮ１对大鼠ＩＡＲＦ模型进行腹主动脉持续灌注３小时。结果发现：ＮＯ供体输入体内可在肾内迅速产生高浓度ＮＯ，可明显改善肾缺血再灌注后的肾皮质缺血，减轻肾功能及组织学损害。结果表明：ＮＯ下降参与了缺血再灌注的肾功能损害，是ＩＡＲＦ发生发展的重要因素之一。ＮＯ缺乏主要导致肾血流量下降，继而ＧＲＦ下降。应用ＮＯ供体直接提供外源性ＮＯ，提高肾内ＮＯ水平可以有效增加肾缺血再灌流后肾血流，改善肾功能，是防治ＩＡＲＦ又一新途径。     

Leukocyte-depleted reperfusion of transplanted human hearts: a randomized, double-blind clinical trial.

Standard methods of myocardial preservation for heart transplantation have generally provided good results. Preservation times beyond 3 hours, however, have been associated with decreased survival. Leukocyte-mediated reperfusion injury is partly responsible for decreased graft function after prolonged graft ischemia. Leukocyte-depleted reperfusion has been shown experimentally to improve cardiac function after cold ischemic arrest. To determine the efficacy and safety of leukocyte-depleted reperfusion, 20 patients were enrolled in a randomized, double-blind clinical trial to be treated with either warm whole blood reperfusion (group I; n = 9) or warm leukocyte-depleted blood reperfusion (group II; n = 11). Reperfusion with leukocyte-depleted blood or whole blood was carried out for 10 minutes, with enriched cardioplegic solution added for the first 3 minutes of reperfusion. The mean donor and recipient age and the ischemic time (142 versus 153 minutes) were not significantly different between the two groups. Coronary sinus release of creatinine phosphokinase-MB 5 minutes after reperfusion was significantly less in group II (1.65 EU/min) than in group I (3.83 units/min; p = 0.05). Thromboxane B2 release was also significantly less (p = 0.05) in group II (33.6 pg/min) than in group I (67.0 pg/min). All hearts functioned adequately in both groups. The duration of inotropic support was shorter in group II than in group I, but the difference was not statistically significant. Postoperative hemodynamics, rejection episodes, and infectious complications were also not significantly different between groups in a mean follow-up of 9 months. Mean ejection fraction 1 month after operation was 65% in both groups. One early death occurred at 66 days secondary to infection; two late deaths occurred in group II, both from rejection. Leukocyte-depleted reperfusion is safe and easily applied in the operating room. Furthermore, leukocyte-depleted reperfusion decreases biochemical evidence of reperfusion injury. Although not influencing postoperative cardiac function when the ischemic time is short, less than 3 hours, leukocyte-depleted reperfusion may prevent significant reperfusion injury and improve posttransplantation graft function when ischemic times are long. Safe extension of the ischemic time would expand the donor pool and allow for better crossmatching.     

Nebivolol Reduces Experimentally Induced Warm Renal Ischemia Reperfusion Injury in Rats

Ischemia/reperfusion injury, which is commonly seen in the field of renal surgery or transplantation, is a major cause of acute renal failure. The objective of the present study was to examine the role of nebivolol in modulating peroxynitrite species-induced inflammation and apoptosis after renal warm ischemia/reperfusion injury in rats. The present study was designed to investigate the effects of nebivolol on the renal warm ischemia/reperfusion injury in rats treated with the nitric oxide synthase inhibitor, N^ω-nitro-L-arginine methyl ester. After right nephrectomy, nebivolol was administered for 15 days. On the 16^th day, ischemia was induced in contra lateral kidney for 45 min, followed by reperfusion for 24 hr. Renal function, inflammation, and apoptosis were estimated at the end of 24 hr reperfusion. Nebivolol improved the renal dysfunction and reduced inflammation and apoptosis after renal ischemia/reperfusion injury. In conclusion, nebivolol shows potent anti-apoptotic and anti-inflammatory properties due to its NO-releasing property. These findings may have major implications in the treatment of human ischemic acute renal failure.