Mucosal villus microcirculatory disturbances associated with rat intestinal ischaemia-reperfusion injury are not prevented by tacrolimus

Combination Therapy of Allopurinol and Dantrolene and Its Role In The Prevention of Experimental Ischemia Reperfusion Injury Of The Small Intestine

BACKGROUND

The effect of different drugs on ischemia and reperfusion (I/R; induced oxygen free radical damage) was examined in small bowel tissue because the intestine is extremely sensitive to this pathology. Different drugs (allopurinol and dantrolene) can remove oxygen free radicals or inhibit the mechanisms leading to their generation, thus reducing mucosal lesions. We investigated the protective potential of combination therapy in the intestine against I/R damage.

METHODS

Forty-eight male Wistar rats were separated into 8 groups: one sham (control), one I/R (ischemia 60 min + reperfusion at 24 h), and 6 groups treated with allopurinol, dantrolene, or combination therapy. The grade of injury in the small bowel was established by the lipid peroxidation (MDA) and antioxidant enzymatic activity of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) in tissue samples. Moreover, the collected samples were subjected to histological study.

RESULTS

Combination therapy preserved normal enzymatic levels compared to the I/R groups (p < 0.05) for all parameters studied. The animals treated with combination therapy showed less severe small bowel damage than I/R group in accordance with the histological results.

CONCLUSIONS

Results obtained in the experimental process indicate that the administration of antioxidants protects against intestinal damage by I/R. Overall, combination therapy may protect intestinal tissue from I/R injury.

Preoperative bombesin administration can protect the rat small bowel allograft from ischemic reperfusion injury

BACKGROUND/PURPOSE

Ischemic reperfusion injury (IR/I) should be minimum for the success of small bowel transplantation (SBTx). This study investigated whether preoperative administration of neuropeptide bombesin (BBS) had a protective effect against IR/I and subsequent acute rejection.

METHODS

Allogenic SBTx was performed heterotopically in rats (n = 18). All rats were administered FK506 (0.32 mg/kg per day) everyday. The rats were divided into 3 groups of 6 rats each: group 1, BBS(-)5: warm ischemic time (WIT), 5 minutes without BBS; group 2, BBS(-)15: WIT, 15 minutes without BBS; group 3, BBS(+)15: WIT, 15 minutes with BBS. The specimens were obtained from the stoma site at 1 hour after reperfusion and on postoperative day (POD) 1 and 7. The graft mucosal state and degree of acute rejection were evaluated by H&E staining. The apoptotic cells in the crypt lesion was evaluated using terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling immunohistochemistry. Apoptotic index (AI) was calculated for quantitative analysis.

RESULTS

H&E staining revealed that the mucosal villi on POD 1 remained shortened in the BBS(-)15 group than in the other two groups. One hour after reperfusion, the AI in the BBS(-)15 group was 145.0 per thousand +/- 37.2 per thousand, which was significantly higher (P < .05) than in the BBS(-)5 group (32.6 per thousand +/- 5.0 per thousand) or the BBS(+)15 group (32.0 per thousand +/- 3.0 per thousand). On POD 7, the AI in the BBS(-)15 group was 63.7 per thousand +/- 5.03 per thousand, which was significantly higher (P < .05) than in the BBS(-)5 (17.3 per thousand +/- 4.6 per thousand) or the BBS(+)15 group (12.3 per thousand +/- 3.06 per thousand).

CONCLUSIONS

Even a short WIT of 15 minutes induced considerable allograft mucosal damage, which also worsened acute rejection. Exogenous BBS could prevent mucosal damage by IR/I and was also beneficial for the prevention of acute rejection.

Ketotifen abrogates local and systemic consequences of rat intestinal ischemia-reperfusion injury

BACKGROUND

Mast cell-derived vasoactive and pro-inflammatory mediators, particularly histamine, might contribute to local tissue damage and multiorgan dysfunction induced by intestinal ischemia/reperfusion (I/R). The purpose of the present study was to evaluate the effects of the mast cell stabilizer, ketotifen, on leukocyte adhesion within, and tissue leakage from the mucosal villous microcirculation after intestinal I/R.

METHODS

Superior mesenteric arteries of untreated and ketotifen-pretreated (1 mg/kg orally twice daily for 3 days, and 90 min prior to ischemia) Piebald-Viral-Glaxo (PVG) rats were clamped for 30 min (n = 12 per group; sham operated controls n = 12). Mucosal surfaces of exteriorized ileal segments were visualized, and leukocyte adherence in, and macromolecular leakage (MML) from individual villi were followed for 2 h after clamp removal using in vivo microscopy. Blood pressure and heart rate were monitored, and lung tissue damage was assessed by histology.

RESULTS

Ten untreated animals subjected to intestinal I/R failed to survive the reperfusion period, leukocyte adhesion (P < 0.001) and MML (P < 0.001) were increased at all time-points and blood flow stasis eventually ensued. In contrast, all ketotifen-pretreated I/R animals survived the duration of the study. Ketotifen abrogated I/R-induced leukocyte adherence within the villus mucosal capillaries and supplying arterioles and largely prevented pulmonary injury, yet surprisingly had no effect on intestinal vascular leakage.

CONCLUSIONS

This is the first study to demonstrate that ketotifen is a powerful inhibitor of I/R-induced leukocyte adhesion and can prevent localized and reduce remote organ damage after intestinal I/R injury. However, its effects are manifested in the absence of any influence on intestinal I/R-induced vascular leakage.