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4.Effect of Superoxide Dismutase and Dimethylthiourea on the Ultrastructure of Hepatocytes in Normothermic Hepatic Ischemia-Reperfusion Injury of Rats.

Nam Cheon CHO ; Doo Jin PAIK ; Byoung Seon RHOE

Journal of the Korean Surgical Society 2000;58(2):149-160

BACKGROUND: Temporary interruption of blood flow to the liver is often unavoidable during operations for extensive injury of the liver or for major liver resection. Following ischemia- reperfusion, transient dysfunction of the liver occurs. It has been suggested that reactive oxygen metabolites play an important role in microvascular reperfusion injury. Superoxide dismutase (SOD) and dimethylthiourea (DMTU) are known to be antioxidants that scavenge oxygen free radicals to reduce microvascular reperfusion injury. This experiment studied the effect of SOD and DMTU on warm ischemia-reperfusion injury to the liver and compared inflow occlusion and hepatic vascular exclusion (HVE) after 20 minutes of ischemia. METHODS: One hundred fourteen healthy male Sprague-Dawley rats weighing around 250 g were used. The rats were divided into control (n=18) and experimental groups (n=96). The control groups included sham, SOD, and DMTU control groups. The experimental groups included inflow occlusion, SOD- pretreated inflow occlusion, DMTU-pretreated inflow occlusion, and inflow and outflow occlusion (HVE) groups. These 4 experimental groups had 24 rats each. The rats were sacrificed immediately, and at 24 hours, 48 hours, and 72 hours after reperfusion, and specimens were obtained from left anterior lobe of the liver. The specimens were prepared using routine methods for electron-microscope observations. RESULTS: The ultrastructures of the hepatocytes in all the experimental groups were similar to those of the normal control rats after just 20 minutes of ischemia. In the inflow occlusion group, dilatation and sacculation of the cisternae of the endoplasmic reticulum and mitochondria with many electron dense granules were observed in the hepatocytes after 24 hours of reperfusion. In the course of reperfusion, damage progressed until 72 hours after reperfusion. The HVE group showed more serious changes than the inflow occlusion group. The SOD- and the DMTU-treated groups showed clear attenuation of liver damage after 48 and 72 hours of reperfusion.CONCLUSION: The ultrastructural changes of hepatocytes after 20 minutes of ischemia became more prominent by prolonging the reperfusion time. The changes after hepatic inflow occlusion were less prominent than those after HVE. DMTU and SOD attenuated the injury to hepatocytes after warm ischemia-reperfusion.
Animals ; Antioxidants ; Dilatation ; Endoplasmic Reticulum ; Free Radicals ; Hepatocytes* ; Humans ; Ischemia ; Liver ; Male ; Mitochondria ; Oxygen ; Rats* ; Rats, Sprague-Dawley ; Reperfusion ; Reperfusion Injury* ; Superoxide Dismutase* ; Superoxides*

8.Effects of DMTU on the Expression of Apoptosis in the Liver of Rats after Ischemia and Reperfusion.

Ik Yong KIM ; Doo Jin PAIK ; Nam Cheon CHO ; Byoung Seon RHOE

Journal of the Korean Surgical Society 2000;59(4):425-432

PURPOSE: Prolonged hepatic ischemia followed by reperfusion in surgery or transplantation results in severe cell death. Apoptosis is one type of cell death and occurs under various conditions. Apoptosis differs from necrosis not only morphologically but also in the mediators and mechanism of injury. It has been recently recognized that oxygen-free radicals are major mediators of apoptosis during ischemia/reperfusion. It was reported that pretreatment with a radical scavenger, such as catalase or superoxide dismutase (SOD) attenuated the apoptotic cell death and that old animals showed a higher catalase, SOD, glutatione peroxidase activity in their livers than young rats. This study was designed to characterize the types of cells within the liver and the extent to which those cells undergo apoptosis during ischemia/reperfusion in rats of different ages and to investigate the effect of dimethylthiourea (DMTU), a scanvenger of reactive hydroxyl radicals, on the induction of apoptosis in old rats. METHODS: Young male Sprague-Dawley rats at 5 weeks of age weighing about 200 gm and old rats at 15 weeks of age weighing about 450 gm were subjected to 30-minute ischemia. Liver ischemia was performed by inflow occlusion. Another group of old rats was injected with DMTU before the clamping. The rats were sacrificed immediately and at 1, 3, and 24 hour(s) after reperfusion. The specimens were prepared using in-situ staining for apoptotic cell and bodies by using terminal deoxytransferase-mediated dUTP- biotin nick-end labelling (TUNEL) methods. RESULTS: The number of apoptotic sinusoidal endothelial cells was larger than the number of hepatocytes during ischemia/reperfusion. The apoptosis of hepatocytes significantly increased at 1 hour and at 3 hours in the young group. Although the number of cells in the old group was lower than that in young rats, an increase of TUNEL positive hepatocytes cells was noted at 1 hour. There was significant increase in the DMTU-pretreated old rats until 24 hours afterreperfusion. The number of apoptotic sinusoidal endothelial cells was noticeably higher in DMTU- pretreated old rats than you only defined two groups previously: old and young in the other group. In young rats, but not old rats, an increase of positive sinusoidal endothelial cells was observed at 1 hours after reperfusion. CONCLUSION: These results suggested that old rats have more resistance to ischemia/reperfusion injury than young rats and that DMTU dose not attenuate apoptosis of sinusoidal endothelial cells after ischemia/reperfusion, but dose attenuate apoptosis of hepatocytes in the liver.
Animals ; Apoptosis* ; Biotin ; Catalase ; Cell Death ; Constriction ; Endothelial Cells ; Hepatocytes ; Humans ; In Situ Nick-End Labeling ; Ischemia* ; Liver* ; Male ; Necrosis ; Peroxidase ; Rats* ; Rats, Sprague-Dawley ; Reperfusion* ; Superoxide Dismutase