Hystopathological study of the intestinal epithelium submitted to different times of programmed ischemia and twenty four hours reperfusion

N-Acetylcysteine Use in Hepatic Ischemia/Reperfusion in Rats Minimizing Bowel Injury

BACKGROUND

The ischemia/reperfusion (I/R) phenomenon can cause the dysfunction of some transplanted organs and other distant organs. Liver surgery success, including transplantations, may depend on the adverse effects of intestinal mucosa injury arising from temporary porta triad occlusion. The study objective was to examine I/R liver effects on the small intestine in rats after N-acetylcysteine (NAC) treatment.

METHODS

Twenty-four male Wistar rats were randomly divided into 2 groups. After anesthesia, they underwent 30 minutes of hepatic ischemia by clamping the porta triad, followed by reperfusion for 30 minutes or 6 hours. Each group was divided into 2 subgroups (n = 6), with 1 group receiving 0.9% saline solution (control) and the other receiving 150 mg/kg of NAC, 15 minutes before hepatic ischemia. At the end of reperfusion, blood was collected for enzyme dosage (alanine aminotransferase [ALT], aspartate aminotransferase [AST], lactate dehydrogenase [LDH], alkaline phosphatase [ALP]), and the terminal ileum was resected to study mucosal morphology by optical microscopy, computerized histomorphometry, and immunohistochemical assessment of apoptosis with caspase 3.

RESULTS

After 30 minutes of reperfusion, animals receiving NAC had lower injury in the intestinal mucosa compared to the control subgroup (P < .05). After 6 hours, AST was higher in the control subgroup than in the NAC subgroup (P < .05), and AST, ALT and LDH values showed a significant increase in both subgroups (P < .05).

CONCLUSION

These findings show the deleterious effects of late (6-hour) reperfusion and the protective effect of NAC at 30 minutes, when evaluating the small intestine impact of I/R liver damage.

Ischemic preconditioning and atenolol on lung injury after intestinal ischemia and reperfusion in rats

The aim of this study was evaluate the beta blocker atenolol (AT) and ischemic preconditioning (IPC) strategies for tissue protection against systemic effects of intestinal ischemia (I) and reperfusion (R) injury. Forty-two rats were pretreated with AT (1.5 mg · kg(-1)), 0.9% saline solution (SS; 0.1 mL), or IPC and then subjected to prolonged occlusion of the superior mesenteric artery for 60 minutes leading to I followed or not by 120 minutes of R, according to the group. For IPC, 5 minutes of I prior to 10 minutes of R were established. After this process of I or I-R, the right lung of each animal was adequately prepared for staining with hematoxylin and eosin and subsequent histologic analysis for quantification of inflammatory infiltrate was done. The left lung was frozen and prepared for assessment of oxidative stress by the quantification of thiobarbituric acid-reactivity substances (TBARS). Histologic analysis showed an important inflammatory infiltrate in the I-R + SS (I-R + SS = 4.5), which was significantly (P < .05) reduced by IPC (I-R + IPC = 3.0) or AT (I-R + AT = 3.0). Likewise, the TBARS levels were decreased by both strategies (I-R + SS = 0.63; I-R + IPC = 0.23; I-R + AT = 0.38; P < .05). Our results showed that AT and IPC attenuate pulmonary lesions caused by intestinal I and R process.

[Mesenteric flow in an experimental model of ischaemia-reperfusion in rats]

INTRODUCTION

Maintained acute occlusion followed by reperfusion of the superior mesenteric artery (SMA) in a few hours can trigger irreversible bowel damage. The aim of the study was to determine the changes in mesenteric flow measured by colour Doppler Ultrasound and correlating with histological lesions in an experimental model of ischaemia-reperfusion.

METHOD AND MATERIAL

Three groups of Sprague-Dawley 17 day-old rats were studied (control, ischemia and reperfusion). The model used was ischaemia-reperfusion over the SMA. Intra-abdominal ultrasound was then performed. The parameters recorded were: Maximum systolic velocity (MSV), pulsatility index (PI), resistance (RI) and systole-diastole (S/D). The histological variables were: intestinal lesion (Wallace/Keenan-Chiu scale), morphometrics (mean villus height [MVH]), and goblet cells. The Spearman (rs) correlation was used.

RESULTS

The MSV in the reperfusion group was 74.3 cm/s, the PI 7.33 and S/D 25.75 in the SMA, which were higher than the controls (41.35 cm/s; 3.12 and 12.45, respectively). A direct association (P<.01) was found between MSV, PI and S/D regarding: Wallace/Kennan scoring system (rs = 0.655; rs = 0.593; rs = 0.63) and the Chiu (rs = 0.569; rs = 0.522; rs = 0.47). While the correlation was the reverse (P<.01) when associated with the MVH (rs = -0,495; rs = -0,452; rs = -0,459) and goblet cells of the colon (rs = -0,525; rs = -0,45; rs = -0,518).

CONCLUSIONS

The reperfusion phase increased mesenteric flow expressed by the MSV and PI and could significantly predict the potential bowel damage at macroscopic and microscopic level.