Intragraft heat shock protein-60 expression after small bowel transplantation in the mouse

The time course of heat shock protein 60 (hsp 60) expression after intestinal transplantation in syngeneic and allogeneic combination was correlated with the degree of rejection. Hsp 60 expression was assessed by immunostaining; rejection degree was established by histologic examination on posttransplantation days 1, 3, 6, and 8. No signs of rejection occurred in syngeneic grafts at any time. In the allogeneic setting, rejection was absent in all but 1 case on postoperative day 3. Three days later moderate rejection was evident based on focal crypt destruction and focal mucosal ulceration, whereas at postoperative day 8 extensive mucosal sloughing was the dominant feature, consistent with advanced rejection. Hsp 60 remained undetectable in the syngeneic setting at all times. In allografts, hsp 60 was initially expressed on posttransplant day 3, increasing synchronously with the progression of rejection at days 6 and 8. Hsp 60 expression was localized almost exclusively to the crypt area and the lower third of the villi. In conclusion, the rejection of murine allogeneic intestinal grafts is characterized by a progressive expression of hsp 60 in the epithelium.     

Effect of whole body hyperthermia on ischemia and reperfusion injury of rat intestine: real-time ATP change studied using (31)P-MRS

We studied the effect of hyperthermia pretreatment on subsequent small intestinal ischemia and reperfusion (I/R) injury in the rat. Systemic hyperthermia has been reported to induce heat shock proteins (HSPs) in several organs [1-6]. We examined the expression of HSP72 in the small intestinal mucosa using Western blotting and immunohistochemistry. We monitored energy metabolism using magnetic resonance spectroscopy continuously during a 60-min ischemia and the following 120 min of reperfusion. Expression of HSP72 in the small intestine was significantly increased at 6-8 h after hyperthermia. Intestinal ischemia was induced by clamping the superior mesenteric artery. Heating of the rat conferred substantial resistance to the I/R injury. In the untreated rats, beta-ATP decreased during ischemia (37.1 +/- 15.5% of the pre-ischemic value) and recovered on reperfusion, but reached only approximately 50% of the pre-ischemic value after 120 min of reperfusion. However, beta-ATP in the pretreated rats was maintained during ischemia at significantly higher levels and on reperfusion reached approximately 80% of the pre-ischemic value. These results indicate that hyperthermia protects the rat intestine from the I/R injury by unknown mechanisms which may include the induction of HSPs.     

Kinetics of heat shock protein 70 synthesis in the human heart after cold cardioplegic arrest.

OBJECTIVE: Protection of the myocardium against ischemia/reperfusion injury is a major challenge in cardiac surgery and cardiology. A cardioprotective role of heat shock proteins (Hsp), in particular Hsp 70, against ischemia has been demonstrated. A prerequisite for clinical exploitation of high Hsp 70 levels in the heart during ischemia is the determination of the efficacy and the kinetics of cardiac Hsp synthesis in vivo. METHODS: We examined Hsp 70 and other immediate early genes, that are induced by cardioplegia and reperfusion, in right atrial biopsies taken from 15 patients during coronary artery bypass grafting. Specimens were obtained before cardioplegia and after ending of reperfusion and subsequently studied by immunohistochemistry and Western blot analyses. RESULTS: Overall Hsp 70 increased 2.0+/-1.1-fold (P<0.01) in the nucleus as well as in the cytosol of myocytes and endothelial cells during open-heart surgery. As determined by comparison to a dilution series of recombinant protein, Hsp 70 levels amounted up to 6 per thousand of total cellular protein. The increase of Hsp 70 correlated well with the duration of cardioplegia and reperfusion (P<0.005) showing a markedly accelerated increase at periods longer than 2 h. Further, the immediate early gene c-Fos also increased 2.4+/-2.2-fold during open-heart surgery (P<0.05), whereas other members of the Hsp family, like Hsp 27 and Hsp 90, showed no significant changes in protein levels during cardioplegia and reperfusion. CONCLUSIONS: These findings demonstrate that protein levels of Hsp 70 in the myocardium increase to significant amounts within few hours after induction. The optimum time point for induction of Hsp 70 appears to be at least 2 h before open-heart surgery.     

Mucosal lesions of the small intestine after intestinal vascular obstruction in the rat

Small intestinal mucosal lesions, characteristically restricted to the villous tissue, have been described in shock states of different types. We have found this type of mucosal lesion in a standardized intestinal ischemia shock in rat. The pathophysiology of the mucosal lesion has been debated. In earlier work we noted a tenfold increase of platelets in the ischemic intestine. The importance of reperfusion and local platelet accumulation for the development of ischemic lesions in the intestinal mucosa was studied. Biopsy specimens taken immediately before and after reperfusion of the ischemic small intestine showed the same degree of mucosal lesion, i.e. total disintegration of the lamina propria. In thrombocytopenic rats subjected to intestinal ischemia, the severity of mucosal lesion was the same as in normothrombocytic rats. The results indirectly support the hypothesis of local villous oxygen deficit as the pathophysiologic mechanism leading to lesions of the small intestinal mucosa in shock.     

Ischemic preconditioning: lack of delayed protection against skeletal muscle ischemia-reperfusion

We investigated the ability of ischemic preconditioning to induce expression of heat shock protein 70 (Hsp 70) and/or to increase muscle survival after ischemia-reperfusion in the rat hind limb. Ischemic preconditioning regimens tested were; 1 x 5 min of ischemia, 4 x 5 min of ischemia interrupted by 10 min of reperfusion, 1 x 10 min of ischemia or 2 x 10 min of ischemia interrupted by 15 min of reperfusion. Western blot analysis revealed only a modest induction of Hsp 70 at 24 h after preconditioning using the latter two protocols of 1 x 10 min of ischemia or 2 x 10 min. Used at 24 h prior to prolonged ischemia, neither protocol improved muscle survival measured at 24 h after reperfusion. In conclusion, ischemic preconditioning did not produce delayed protection from ischemia-reperfusion in this model and the study suggests that ischemic preconditioning is not a useful protective strategy against skeletal muscle necrosis in the long-term.     

Heat shock preconditioning and eicosanoid pathways modulate caspase 3-like activity in superficially injured isolated guinea pig gastric mucosa

BACKGROUND: After superficial mucosal injury, the disturbed gastric epithelial continuity is restored by cellular migration. Caspase-3 is an enzyme responsible for the execution of stress-induced apoptosis. Interestingly, heat shock proteins (Hsp) including Hsp60 are capable of modulating caspase-3 activity. Interestingly, we have demonstrated that heat shock preconditioning upregulates Hsp synthesis and inhibits restitution and cell proliferation via mechanisms related to de novo protein synthesis and eicosanoid pathways, both of which are crucial in the regulation of apoptosis and gastric mucosal defense systems. AIMS: To assess whether caspase-3 activity is affected by heat shock preconditioning and associated pharmacological modulations after standard superficial injury to allow development of cytoprotective strategies. METHODS: Guinea pig gastric mucosae were mounted and perfused in paired Ussing chambers. After heat shock (HS) preconditioning (42 degrees C) for 30 min, a superficial injury was induced (1.25 mol/l NaCl) followed by 3 h recovery. For mechanistic studies, the mucosa was exposed to 30 micromol/l arachidonic acid (AA) as a substrate for eicosanoid pathways, to 50 micromol/l quercetin (Q) to inhibit lipoxygenases, to 50 micromol/l indomethacin (In) to inhibit cyclo-oxygenases, or to 150 micromol/l cycloheximide (CHX) to inhibit de novo protein synthesis. After the experiment, the mucosa was prepared for analysis of caspase-3 activity. Hsp60 expression was analyzed to monitor the induction of heat shock response. RESULTS: HS upregulated Hsp60 expression, indicating induction of the heat shock response without an effect on basal caspase-3 activity. Superficial injury itself did not affect caspase-3 activity nor Hsp60 synthesis. In all the experiments, exposure to CHX abolished caspase-3 activity and Hsp60 synthesis. AA+Q increased, Q decreased, while In+AA and In+AA+Q abolished caspase-3 activity independent of alterations in Hsp60 synthesis. Upon exposure to In+Q, HS decreased caspase-3 activity and upregulated Hsp60 synthesis. CONCLUSION: Caspase-3 activity in isolated guinea pig gastric mucosa is regulated by mechanisms dependent on de novo protein synthesis and eicosanoid pathways but is not strictly related to Hsp synthesis. Upon modulation of the eicosanoid pathways, HS may be utilized to simultaneously decrease caspase-3 activity and increase Hsp synthesis. Modulations of the eicosanoid pathways may be utilized to reduce caspase-3 activity also upon normothermic conditions suggesting a novel mechanism by which caspase-3 is regulated in the gastric mucosa.     

大鼠烫伤早期肠黏膜组织热休克蛋白HSP70和HSP90的表达

目的 研究烧伤早期肠黏膜组织热休克蛋白HSP70和HSP90的表达、组织含量和分布的变化规律,探讨烧伤早期肠黏膜组织细胞的热休克反应在机体的病理生理反应中的意义。方法 以烫伤大鼠为模型,利用ELISA、免疫印迹分析和免疫组织化学方法,分析和研究肠黏膜组织HSP70和HSP90的表达、组织含量和分布及其功能状态。结果 (1)大鼠烫伤早期肠黏膜游离HSP70的含量有非常显的短暂降低;(2)肠黏膜组织HSP70和HSP90的总体含量在烧伤后有显升高;(3)烧伤早期肠黏膜组织HSP70的分子结构存在显的不均一性。结论 肠黏膜组织细胞中两种热休克蛋白表达、含量和分布的规律性变化,在肠黏膜组织细胞的应激反应、进而在肠道的黏膜屏障机制中,可能有重要的意义。     

Myocardial self-preservative effect of heat shock protein 70 on an immature lamb heart

BACKGROUND: Heat shock proteins have been shown to enhance myocardial tolerance of ischemia-reperfusion injury and are induced in the myocardium of many animals by various stressors. METHODS: To assess the effects and time course of the inducible form of heat shock protein 70, we raised the rectal temperature of 15 neonatal lambs to 43 degrees C for 15 minutes. At 15, 30, 60, and 120 minutes and 24 hours after heat shock, hearts were subjected to immunoblot analysis for heat shock protein (hsp 72/73). Twenty-four hours after heat shock, neonatal lamb hearts (n = 8) were subjected to 2 hours of cold cardioplegic ischemia (HSP group). Eight neonatal lamb hearts without heat shock served as control. After 60 minutes of reperfusion, left ventricular systolic and diastolic function, coronary blood flow (CBF), myocardial oxygen consumption (MVO2), and lactate levels were measured. Endothelial function was assessed by measuring in situ coronary vascular resistance response to acetylcholine and trinitroglycerine. RESULTS: The HSP group showed a significantly higher recovery of systolic function as well as MVO, and a lower lactate level compared to the control group at 60 minutes after reperfusion. Recovery of coronary endothelial function was also significantly better in the HSP group than in the control group. Inducible form of HSP 70 was expressed 15 minutes after heat shock and continued to be observed at 24 hours after the stress. CONCLUSIONS: Heat shock stress associated with the production of inducible heat shock proteins improved the recovery of ventricular function as well as endothelial function and aerobic metabolism after hypothermic cardioplegic ischemia. Induction of heat shock proteins by any means prior to planned hypothermic ischemia may lead to a new approach for myocardial protection.     

Heat shock preconditioning on mitochondria during warm ischemia in rat livers

BACKGROUND: The aim of this study was to investigate the effects of stress tolerance from heat shock preconditioning on changes in mitochondrial functions during ischemia-reperfusion injury of the liver. MATERIALS AND METHODS: Rats were divided into a heat shock group (group HS) and a control group (group C). In group HS, rats received heat shock pretreatment 48 h prior to ischemia-reperfusion. Heat shock pretreatment was performed in a water bath at 42 degrees C for 15 min under general anesthesia. In group C, the same treatment was done with the water bath at 37 degrees C instead of at 42 degrees C. A 30-min warm ischemia by cramping the hepatoduodinal ligament (Pringle's maneuver) followed by a 60-min reperfusion was administered to all rats. Changes in membrane potential of hepatic mitochondria (MPM); mitochondrial respiratory function before ischemia (n = 5), after ischemia (n = 10), and after reperfusion (n = 10); and ATP recovery after reperfusion were compared between the groups. RESULTS: After a 30-min ischemia, MPM in group C decreased significantly and did not recover even after reperfusion. On the other hand, MPM in group HS was maintained even after a 30-min ischemia and 60 min into reperfusion as well. The respiratory control ratio (RCR) of the mitochondria in group C decreased to as low as 5.06 +/- 0.72 after a 30-min ischemia, but in group HS, RCR was maintained near a normal level. The ATP level recovered significantly earlier in group HS than in group C after reperfusion. CONCLUSIONS: Heat shock preconditioning of the liver protected mitochondria from loss of membrane integrity during ischemia and contributed to their ability to produce energy-rich phosphates during reperfusion.     

Differential expression of heat shock proteins 70-1 and 70-2 mRNA after ischemia-reperfusion injury of rat kidney

Ischemia-reperfusion injury in the kidney is known to cause induction of the inducible form of the 70 kDa heat shock protein HSP70i (or HSP72). However, knowledge of the expressional regulation of the two coding genes for HSP70i –HSP70-1 gene and HSP70-2 gene – is very limited. We investigated the time course of HSP70-1 and -2 mRNA expression and its relation to cellular ATP levels in the renal cortex after different periods of unilateral warm renal ischemia (10–60 min) and reperfusion (up to 60 min) in 10-week-old male Wistar rats. Immediately after ischemia there was a significant induction of both HSP70i genes. While HSP70-1 expression constantly increased (up to 4-fold) during reperfusion, even to a higher extent with prolongation of ischemia, HSP70-2 mRNA – which was generally expressed at a far lower level than HSP70-1 mRNA – was strongly induced (3-fold) during reperfusion only after brief periods (10 min) of ischemia. Cellular ATP levels rapidly dropped to 5% with ischemia and the pattern of recovery during reperfusion significantly depended on the duration of the ischemic period, thus showing a good relation with the heat shock (protein) gene expression. We conclude that HSP70-2 is the more sensitive gene with a lower activation threshold by mild injury, while the HSP70-1 gene mediates the major response of heat shock protein induction after severe injury. Received: 16 November 1998 / Accepted: 11 March 1999     

Stress responses in graft and native intestine after rat heterotopic small bowel transplantation

BACKGROUND: Cardiac transplantation has been shown to induce heat shock protein expression, and reactivity to these stress proteins has been implicated in acute and chronic allograft rejection. This study assessed Hsp60 and Hsp70 expression in graft and native small intestine after rat small bowel transplantation. METHODS: Heterotopic small bowel transplantation was performed between PVG donor and DA recipient rats, a subgroup of which received tacrolimus immunosuppression (1 mg x kg(-1) x day(-1)). Untransplanted and isografted (PVG-->PVG) animals served as controls. Paraffin sections of graft and native intestine on day 5 after transplantation were stained by immunohistochemistry, and heat shock protein expression was graded blindly by three observers. RESULTS: Villus epithelial cell expression of Hsp60, but not Hsp70, was increased in allografts. The induction of Hsp60 in the villus epithelium was not controlled by tacrolimus. Hsp60 and Hsp70 expression was induced in the lamina propria of isografts and allografts. This response was more pronounced in allografts and was significantly reduced, but not totally abrogated, by tacrolimus. Interestingly, heat shock protein expression was also induced in the native intestine lamina propria and epithelium of allograft recipients, suggesting the induction of stress responses at sites other than the transplanted organ. CONCLUSIONS: Small bowel transplantation induces a stress response in both the graft and native intestine. The early and prolonged expression of these proteins may influence the induction of anti-heat shock protein reactivity and have an adverse effect on graft outcome after small bowel transplantation.     

Heat shock protein upregulation lowers cytokine levels after ischemia and reperfusion.

OBJECTIVE: Studies showed that the expression of heat shock protein 70 (HSP70) by whole-body hyperthermia or warming of the heart is associated with protection against ischemia/reperfusion injury. The aim of this study is to determine a time-related response of HSP70 expression through topical cardiac warming with correlation to cytokine production. METHODS: 30 rats were divided into three groups: no heat shock, heat shocked, and controls. Heat shock was performed with 42 degrees C saline solution applied to the heart for 5, 30, and 60 min. HSP70 and cytokines were measured. RESULTS: Heat shock treated animals showed a 1.2-fold increase after 5 min (NS) in HSP70 expression, a 2.0-fold increase (p < 0.02) after 30 min, and a 2.3-fold increase (p < 0.012) after 60 min compared to controls. The IL-1beta levels decreased from 14.3 pg/ml (normal controls) to 7.1 pg/ml after 5 min, to 1.6 pg/ml after 30 min (p < 0.002), and to 1.4 pg/ ml after 60 min of heat shock treatment (p < 0.002). The TNF-alpha levels also decreased, but not significantly. CONCLUSIONS: Upregulation of HSP70 through this novel method is instant and detectable within hours. The amount of HSP70 expression induced is time dependent, showing an indirect correlation with cytokine levels. These results suggest that the protective effect of HSP70 is immediate and might be explained by reduced cytokine levels. No prior recovery period is needed.     

Heat shock protein and high-dose aspirin: effects on random skin flap survival in a rat model.

The heat shock response is known to have a protective effect against flap ischemia. It has been shown that heat shock protein (hsp) expression can be augmented in vivo with the administration of high-dose aspirin before heat treatment. The authors hypothesized that administration of aspirin before hsp induction through heat stress would enhance further the protective effects of the heat shock response against skin flap ischemia. They used a random dorsal skin flap model in 32 rats divided into four groups (N = 8 each): control, heat shock, aspirin plus heat shock, and aspirin. Before surgery, rats in the two heat shock groups were placed in a 45 degrees C water bath until core body temperature measured 42 degrees C, and they were maintained at 42 degrees C for 15 minutes. Rats in the two aspirin groups received a single oral dose of aspirin (100 mg per kilogram) 1 hour before heat bath or surgery. Immunohistochemistry confirmed hsp expression in the two heat groups. Skin flap survival was improved significantly (p < 0.05) in the heat shock (55%), aspirin plus heat shock (58%), and aspirin (60%) groups when compared with controls (45%). Contrary to their hypothesis, aspirin combined with hsp induction did not offer greater protection from ischemia than hsp induction alone (p > 0.05). However, high-dose aspirin administration alone did improve skin flap survival when compared with controls. Future studies are needed to investigate further the role of pharmacological therapy combined with hsp induction in improving skin flap survival and to delineate the dose-response relationship between aspirin and hsp.     

Effect of 43℃ treatment on expression of heat shock proteins 105, 70 and 60 in cultured monkey Sertoli cells

AIM: To examine the possible effect of heat treatment on expression of heat shock proteins (Hsps) 105, 70, and 60 in primary monkey Sertoli cells and to evaluate the possible signal pathways. METHODS: Western blot analysis, real-time polymerase chain reaction (PCR), and confocal immunohistochemistry were used to analyze mRNA and protein levels of the Hsps in response to 43 degrees treatment of Sertoli cells isolated from pubertal monkey testes. RESULTS: Staining with Hoechst 33342 indicated Sertoli cells did not undergo apoptosis after heat treatment. Hsp105 was expressed in cytoplasm of untreated Sertoli cells. Both Hsp105 mRNA and protein levels were increased approximately 20-fold compared to those of the untreated controls at 12 h after heat treatment. Untreated Sertoli cells did not express Hsp70, but heat stress induced its expression in the cell cytoplasm. The time-course of changes in Hsp70 was similar to that of Hsp105. In contrast to Hsp105 and Hsp70, the change in Hsp60 expression was much less obvious. The protein level between 12 h and 48 h after heat treatment was only approximately 1.5-fold that of the untreated control. Extracellular regulated kinase (ERK) 1/2 inhibitor (U0126) or phosphoinositide kinase-3 (PI3K) inhibitor (LY294002) could partially block the response of Hsp105 and Hsp70 induced by heat treatment. CONCLUSION: These results indicate that the heat-induced expression of the three types of Hsp in monkey Sertoli cells might be regulated by ERK and/or PI3K signal pathways, but the profile of their expression is different, suggesting that they might have different regulatory functions in Sertoli cells.     

Ergothioneine modulates proinflammatory cytokines and heat shock protein 70 in mesenteric ischemia and reperfusion injury

BACKGROUND AND AIM: Ergothioneine (EGT) is a natural compound that is synthesized by soil bacteria in fungal substrates and exhibits antioxidant functions in many cell models. The purpose of this study was to investigate the effect of EGT on mesenteric ischemia and reperfusion injury. MATERIALS AND METHODS: Rats were supplemented with or without l-ergothioneine (10 mg/kg/d) for 15 days prior to intestinal ischemia. Animals were subjected to ischemia induced by clamping the superior mesenteric artery for 60 min followed by reperfusion. Serum tumor necrosis factor (TNF)-alpha and interleukin-1beta (IL-1beta) levels, tissue malondialdehide (MDA), myleoperoxidase (MPO), and heat shock protein (HSP) 70 levels, as well as histological findings, were evaluated after 1, 2, and 4 h of reperfusion. RESULTS: Serum TNF-alpha and IL-1beta levels, and tissue MDA and MPO activities at 1, 2 and 4 h after reperfusion in the EGT group, were significantly lower than the control group (P < 0.05). Tissue HSP-70 levels of the study group were significantly greater than the control group at any time point of reperfusion. No significant differences in tissue damage including morphological changes ranging from villous denudation to focal necrosis, ulceration, hemorrhage, and architectural disintegration at 1 and 2 h after reperfusion exist between the two groups; however, after 4 h of reperfusion, the tissue damage based on histopathologic scores by Chiu was considerably lower in the study group (P < 0.05). After 4 h of reperfusion, focal epithelial lifting and occasional areas of denuded villi could be seen in the samples of the treated animals, thus preserving villous height and mucosal architecture. CONCLUSION: EGT attenuates mesenteric ischemia reperfusion injury in rat intestine by increasing tissue HSP-70 and decreasing TNF-alpha, IL-1beta, MDA, and MPO levels. EGT also improves morphological alterations, which occurred after IR injury after prolonged periods of reperfusion.     

Heat shock protein 70: correlation of expression with degree of graft-versus-host response and clinical graft-versus-host disease

BACKGROUND: The heat shock proteins are increasingly becoming associated with immunopathologic phenomena, being induced in response to inflammation. They are highly immunogenic and are postulated as playing a role in both innate and adaptive immunity. Their proposed role in peptide binding and antigen presentation could suggest a potential role in the alloreactive process that leads to graft-versus-host disease (GVHD) after bone marrow transplantation. METHODS: In this study we examined the expression of the widely studied heat shock protein 70 (hsp70) in an in vitro-generated graft-versus-host reaction in human skin, using streptavidin biotin immunohistochemistry and laser scanning confocal microscopy. RESULTS: Hsp70 expression was correlated with high graft-versus-host responses (P<0.001) and was confirmed using laser scanning confocal microscopy. Increased expression of hsp70 was further defined due to increases in the inducible form of hsp70. Expression of inducible hsp70 was predictive of both clinical acute GVHD (P=0.001) and incidence of chronic GVHD (P<0.001). CONCLUSIONS: This investigation has demonstrated for the first time the expression of hsp70 in a human model of GVHD, suggesting involvement in the pathogenesis of the disease and providing the basis for further investigation. Increased expression of inducible hsp70 in the model could provide a biologic marker for the prediction of clinical acute and chronic GVHD.     

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.     

Insulin potentiates expression of myocardial heat shock protein 70.

OBJECTIVE: Since insulin stimulates nitric oxide (NO) production and an increase in NO following heat shock is required for myocardial heat shock protein 70 (Hsp70) synthesis, we hypothesized that insulin would enhance myocardial Hsp70 synthesis by augmenting NO signaling. We examined whether a physiologic dose of insulin increased myocardial Hsp70 in unstressed and heat shock treated rats. METHODS: Adult male Sprague-Dawley rats were assigned to groups: (1) control, (2) insulin injected (200 microU/gm body weight), (3) heat shock treated (core body temperature 42 degrees C for 15 min), (4) heat shock and insulin treated, (5) L-nitroarginine methyl ester (L-NAME) and heat shock and insulin treated, (6) sodium nitroprusside (SNP) and heat shock and insulin treated. Six hours later, myocardial Hsp70 content and localization was analyzed. RESULTS: Hsp70 was increased in heat shock treated hearts (120.6+/-16.8 ng/mg protein, P < 0.001) vs. control (12.9+/-2.0 ng/mg protein), or insulin treated hearts (15.5+/-0.83 ng/mg protein). In addition, Hsp70 was increased in the heat shock and insulin treated hearts (164.4+/-7.53 ng/mg protein) compared to control, insulin only (P = 0.001) or heat shock only treated hearts (P = 0.01). L-NAME did not abolish the insulin induced increase in Hsp70 in heat shocked hearts (195.2+/-13.4 ng/mg protein, P = 0.21) and SNP did not further enhance Hsp70 in the insulin and heat shocked group (188.9+/-8.2 ng/mg protein, P = 0.71). Western analysis and confocal microscopy revealed a lowlevel expression of myocardial Hsp70 in response to insulin. Hsp70 was localized primarily in blood vessels after insulin or heat shock treatments. CONCLUSIONS: Insulin caused a low-level expression of myocardial Hsp70 and potentiated Hsp70 synthesis in response to heat shock. The ability of insulin to potentiate Hsp70 after heat shock is independent of NO signaling as it was not altered by either LNAME or SNP pretreatment. Blood vessels appear to be the primary site of Hsp70 after insulin or heat shock treatment.