(1/99) Calcium channel blocker and renal mitochondrial function in warm renal ischemia.

OBJECTIVE: Ions, particularly calcium ions, play an important role in ischemia-reperfusion cell injury. In this study, we investigated the action of verapamil on the mitochondrial function of kidneys submitted to ischemia without blood reperfusion in order to study isolated early and late ischemic effects. MATERIALS AND METHODS: 44 rats were submitted to bilateral warm renal ischemia for 30 minutes. The kidneys were then immediately reperfused with saline or Euro-Collins (EC) solution, with and without previous administration of 0.35 mg/kg of verapamil. Mitochondrial function was assessed at the end of renal perfusion and after 24 hours of cold preservation. RESULTS: In kidneys perfused with saline, verapamil allowed a significant early preservation of state III mitochondrial respiration, a result that was no longer evident after 24 hours. In kidneys perfused with EC solution, verapamil did not change state III for either early or late evaluations. Comparison of the groups showed that the results obtained for kidneys perfused with EC were always superior to those obtained for the saline group, except for the initial analysis of kidneys treated with saline and verapamil, which showed results similar to those obtained with EC perfusion alone. CONCLUSION: Administration of verapamil before warm ischemia provides partial and short-lasting functional protection of the mitochondrial function in kidneys perfused with sodium rich saline. With Euro-Collins solution, verapamil did not show any additional beneficial effect. This fact permits us to conclude that protective action is effective only under conditions that facilitate increased sodium uptake and/or potassium loss.  (+info)

(2/99) Influence of perfusion by gaseous oxygen persufflation on rat donor liver.

BACKGROUND: Hepatic ischemia-reperfusion injury is one of the major problems in liver transplantation. This study aimed to investigate the possible improvement of aerobic metabolism of ischemic donor livers through systemic persufflation with gaseous oxygen in rinse solution. METHODS: Thirty rats were randomly divided into 3 groups. In group A (control, n=10), the livers were perfused with 4 degree centigrade lactic acid ringer's solution through the cannulated portal vein for 25 minutes soon after warm ischemia for 30 minutes. In group B (n=10), the livers were treated the same way as in group A except for addition of gaseous oxygen in the rinse solution. In group C (n=10), the livers were treated similarly as in group B except for addition of superoxide dismutase (SOD) in the rinse solution. RESULTS: In group B, the malondialdehyde (MDA)levels in hepatic tissues after perfusion were significantly increased (P<0.01), whereas the SOD levels were markedly decreased (P<0.01). After combined use with antioxidant in group C, the levels of MDA and SOD in hepatic tissues after perfusion recovered significantly (P<0.01). CONCLUSION: Perfusion by gaseous oxygen persufflation in combination with antioxidative agents is promising for resuscitating the ischemically altered livers for successful transplantation.  (+info)

(3/99) Protecting the myocardial cell during coronary revascularization. The William W. L. Glenn Lecture.

BACKGROUND: Using the ischemic myocardial cell as a paradigm, competitive coronary revascularization technologies will be analyzed for their potential in causing additional myocardial cell damage during the course of therapeutic procedures. METHODS AND RESULTS: Percutaneous coronary intervention (PCI) using balloon and/or stent (bare metal or coated) approaches may be associated with myonecrosis related to atherosclerotic debris plugging the downstream coronary microcirculation as well as ischemia/reperfusion injury associated with revascularization of occluded coronary vessels. The placement of distal mechanical devices and filters during the course of PCI has not been successful in ameliorating this problem. Coronary revascularization using coronary artery bypass grafting (CABG) similarly may be associated with myocardial stunning and cell necrosis associated with ischemia/reperfusion injury. Surgically induced myocardial ischemia secondary to aortic cross clamping, results from the attenuation or cessation of coronary blood flow such that oxygen delivery to the myocardium is insufficient to meet basal myocardial requirements to preserve cellular membrane stability and viability. Recovery involves: (1) resumption of normal oxidative metabolism and the restoration of myocardial energy reserves; (2) reversal of ischemia induced cell swelling and loss of membrane ion gradients and the adenine nucleotide pool; (3) repair of damaged cell organelles such as the mitochondria and the sarcoplasmic reticulum. Despite meticulous adherence to presently known principles of surgical myocardial protection using advanced cardioplegic technologies, some patients require inotropic support and/or mechanical assist devices postoperatively, when none was required preoperatively. CONCLUSIONS: Which method of coronary revascularization causes the least amount of myocardial cell injury and is associated with superior long-term outcomes remains an area of increasing controversy.  (+info)

(4/99) Dynamical changing patterns of histological structure and ultrastructure of liver graft undergoing warm ischemia injury from non-heart-beating donor in rats.

AIM: To investigate the histological and ultra-structural characteristics of liver graft during different of warm ischemia time (WIT) in rats and to predict the maximum limitation of liver graft to warm ischemia. METHODS: The rats were randomized into 7 groups undergoing warm ischemia injury for 0, 10, 15, 20, 30, 45 and 60 min, respectively. All specimens having undergone warm ischemia injury were investigated dynamically by light and electron microscopy, and histochemistry staining. After orthotopic liver transplantation (OLT), the recovery of morphology of liver grafts after 6, 24 and 48 h was observed. RESULTS: The donor liver from non-heart-beating donors (NHBD) underwent ischemia injury both in the warm ischemia period and in the reperfusion period. Morphological changes were positively related to warm ischemia injury in a time-dependent manner during the reperfusion period. The results demonstrated that different degrees of histiocyte degeneration were observed when WIT was within 30 min, and became more severe with the prolongation of WIT, no obvious hepatocyte necrosis was noted in any specimen. In the group undergoing warm ischemia injury for 45 min, small focal necrosis occurred in the central area of hepatic lobule first. In the group undergoing warm ischemia injury for 60 min, patchy or diffused necrosis was observed and the area was gradually extended, while hepatic sinusoid endothelial cells were obviously swollen. Hepatic sinusoid was obstructed and microcirculation was in disorder. CONCLUSION: The rat liver graft undergoing warm ischemia injury is in the reversible stage when the WIT is within 30 min. The 45 min WIT may be a critical point of rat liver graft to endure warm ischemia injury. When the WIT is over 60 min, the damage is irreversible.  (+info)

(5/99) Spatiotemporal expression of heme oxygenase-1 detected by in vivo bioluminescence after hepatic ischemia in HO-1/Luc mice.

Upregulation of heme oxygenase-1 (HO-1) has been proposed as a critical mechanism protecting against cellular stress during liver transplantation, providing a potential target for new therapeutic interventions. We investigated the feasibility of in vivo bioluminescence imaging (BLI) to noninvasively quantify the spatiotemporal expression of HO-1 after warm hepatic ischemia in living animals. Luciferase activity was measured by BLI as an index of HO-1 transcription in transgenic reporter mice (Ho1-luc) at standardized time points after 60 minutes of warm hepatic ischemia. HO-1 mRNA levels were measured in postischemic livers of mice sacrificed at the same time points in separate experiments. Bioluminescent signals from postischemic liver lobes were first detected at 3 hours after reperfusion. Peak levels were reached at 9 hours, after which bioluminescent activity declined and returned to baseline values at 48 hours after reperfusion. Upregulation of HO-1 as detected by in vivo BLI was preceded by increased HO-1 mRNA expression and confirmed by enhanced immunohistochemical staining of hepatocytes. In conclusion, this study shows that in vivo BLI allows a sensitive assessment of HO-1 expression after hepatic ischemia in living animals. The capability of whole-body temporal imaging of HO-1 expression provides a valuable tool in the development of novel strategies to modulate HO-1 expression in liver transplantation.  (+info)

(6/99) Prolonging warm ischemia reduces the cold preservation limits of liver grafts in swine.

BACKGROUND: The critical shortage of transplantable organs necessitates utilization of unconventional donors. But the safe time limits of cold preservation of liver grafts subjected to warm ischemia (WI) for up to 30 minutes from non-heart-beating-donors (NHBDs) has not been delineated. In this study, we investigated how the limits of cold ischemia (CI) in University of Wisconsin (UW) solution are changed in liver grafts subjected to WI from 10 to 30 minutes. METHODS: A simple porcine NHBD liver transplantation (LT) model was developed. In donors, livers were subjected to 10, 20 or 30 minutes of WI and subsequent different times of CI in UW solution. Animals were divided into three groups (WI 10 min, WI 20 min, WI 30 min, n=13 in each group) and nine subgroups (from CI 6 h to CI 28 h). One-week survival rates of recipients, hepatic function, liver energy metabolism, grafted liver microcirculation and pathological observations of the liver were compared. RESULTS: In the WI 10 min group, the one-week survival rate of the CI 20 h subgroup was significantly higher than in the other two subgroups (CI 24 h and CI 28 h) (P<0.05). Furthermore, the CI 20 h subgroup had a lower level of alanine aminotransferase (ALT), less pathological damage, a higher concentration of adenosine triphosphate (ATP) and microcirculatory blood flow in the grafted livers at 1 hour after reperfusion than the other two subgroups. The same trends were also found in the other two groups (WI 20 min and WI 30 min) and their subgroups. CONCLUSIONS: The cold preservation limits of the liver grafts shortened from 20 to 12 to 6 hours when WI time was prolonged from 10 to 20 to 30 minutes. Only the liver grafts within these time limits could be safely transplanted.  (+info)

(7/99) Energy metabolism and survival of liver grafts from non-heart-beating donor rats with warm ischemia injury.

BACKGROUND: The shortage of donor livers is a critical limiting factor for the use of liver transplantation in treatment of end-stage liver diseases. Organs from non-heart-beating donors seem to be an effective option to alleviate this problem. Warm ischemia injury, however, directly influences the grafts' activity and functional recovery after operation. We investigated the energy metabolism and post-transplant survival of liver grafts after different warm ischemia times (WITs) in rats and determined the maximum limit for liver grafts with warm ischemia. METHODS: Rats were randomized into 7 groups with WITs of 0 (control), 10, 15, 20, 30, 45 or 60 minutes. The indices of energy metabolism were measured by reversed-phase high performance liquid chromatograpy and all liver graft specimens were subjected to ultrastructural observation. After orthotopic liver transplantation (OLT), the recovery of energy metabolism in liver grafts after 24 and 48 hours and the survival of the rats were assessed. RESULTS: The levels of adenosine triphosphate (ATP) and energy charge (EC) decreased gradually after different WITs in a time-dependent manner, and this was especially significant within 30 minutes. The levels of ATP and EC in liver grafts with 30 minutes of warm ischemia largely recovered 24 hours after OLT, with 45 minutes of warm ischemia partially recovered 48 hours after OLT, and with 60 minutes of warm ischemia, hardly recovered even 48 hours after OLT. The survival time after OLT did not significantly change with up to 30 minutes of WIT, while long-term survival was reduced with 45 and 60 minutes of WIT. CONCLUSIONS: The levels of ATP and EC after OLT may be important criteria for evaluating the quality of a liver graft. The WIT of a liver graft is closely related to the recovery of hepatic energy metabolism and the graft survival.  (+info)

(8/99) Novel short-term hypothermic oxygenated perfusion (HOPE) system prevents injury in rat liver graft from non-heart beating donor.

OBJECTIVE: To assess a machine perfusion system in rescuing liver grafts from non-heart-beating donors (NHBD). SUMMARY BACKGROUND DATA: The introduction of extracorporeal liver perfusion systems in the clinical routine depends on feasibility. Conceivably, perfusion could be performed during recipient preparation. We investigated whether a novel rat liver machine perfusion applied after in situ ischemia and cold storage can rescue NHBD liver grafts. METHODS: We induced cardiac arrest in male Brown Norway rats by phrenotomy and ligation of the subcardial aorta. We studied 2 experimental groups: 45 minutes of warm in situ ischemia + 5 hours cold storage versus 45 minutes of warm in situ ischemia + 5 hours cold storage followed by 1 hour hypothermic oxygenated extracorporeal perfusion (HOPE). In both groups, livers were reperfused in a closed sanguineous isolated liver perfusion device for 3 hours at 37 degrees C. To test the benefit of HOPE on survival, we performed orthotopic liver transplantation in both experimental groups. RESULTS: After cold storage and reperfusion, NHBD livers showed necrosis of hepatocytes, increased release of AST, and decreased bile flow. HOPE improved NHBD livers significantly with a reduction of necrosis, less AST release, and increased bile flow. ATP was severely depleted in cold-stored NHBD livers but restored in livers treated by HOPE. After orthotopic liver transplantation, grafts treated by HOPE demonstrated a significant extension on animal survival. CONCLUSIONS: We demonstrate a beneficial effect of HOPE by preventing reperfusion injury in a clinically relevant NHBD model.  (+info)