SILDENAFIL IS NOT PROTECTIVE TO THE BOWEL FOLLOWING INTESTINAL ISCHEMIA AND REPERFUSION INJURY

Background and Hypothesis: Acute Mesenteric Ischemia (AMI) occurs when blood supply to the intestine is decreased. This can lead to intestinal ischemia, cellular damage, necrosis, and if corrected, subsequent reperfusion injury. There are currently no medical treatments to help reverse ischemia and reperfusion injury (I/R) and, therefore novel treatments are necessary. Sildenafil, a compound that increases endogenous nitric oxide (NO) by blocking the phosphodiesterase-5 induced breakdown of cGMP, may function as a potent mesenteric vasodilator. We therefore hypothesized that sildenafil would improve mesenteric perfusion during a mouse model of intestinal I/R.  Experimental Design or Project Methods: Adult male C57Bl6J mice were anesthetized with isoflurane and a midline laparotomy performed. The base of the superior mesenteric artery was occluded with a non-crushing vascular clamp for 60 minutes. At the end of ischemia, sildenafil (1mg/kg, 10mg/kg, or 100mg/kg) or a PBS vehicle control were administered via intraperitoneal injection. Animals were then allowed to recover. Twenty-four hours after ischemia, animals underwent assessment of mesenteric perfusion by Laser-Doppler imaging. Animals were then euthanized. Perfusion was expressed as a percentage of baseline, depicted as mean +/- SEM, and analyzed by ANOVA. P<0.05 was significant. Results: There were no significant differences in mesenteric perfusion between the vehicle group or any of the therapeutic groups. (PBS: 53.03±11.35%; Sildenafil-low: 59.59±7.55%; Sildenafil-medium: 70.51±8.49; Sildenafil-high: 66.4±10.2, p=0.61). Conclusion: Sildenafil does not appear to be an effective treatment for improving mesenteric perfusion following intestinal ischemia. Further studies are required to determine the reasons for the ineffectiveness of sildenafil. One possible explanation for these observations could be a lack of PGE5 in the intestinal vascular endothelium.

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Photoacoustic Imaging in Evaluating Early Intestinal Ischemia and Reperfusion Injury with Rat Models

10.21203/rs.3.rs-94473/v1 ◽

2020 ◽

Author(s):

Rui Wang ◽

Teng Pan ◽

Lin Huang ◽

Chengde Liao ◽

Qinqing Li ◽

...

Keyword(s):

Reperfusion Injury ◽

Intestinal Ischemia ◽

Photoacoustic Imaging ◽

Ischemia Reperfusion ◽

Acute Mesenteric Ischemia ◽

Tunel Staining ◽

Time Interval ◽

Ischemia And Reperfusion ◽

Ischemia And Reperfusion Injury ◽

Ischemia Group

Abstract Purpose: It is still a challenge to distinguish whether the damaged intestine is viable or not in the treatment of acute mesenteric ischemia. In this study, photoacoustic imaging (PAI) was used to observe the activity of intestinal tissue after ischemia and reperfusion injury in rats.Methods: With the approval of animal ethics committee our university, in vivo study was carried out. Forty male SD rats were randomly divided into four groups: sham operated (SO) group, 1 h ischemia group, 2 h ischemia group and ischemia-reperfusion (I/R) group. In the ischemia group, superior mesenteric artery (SMA) was isolated and clamped for 1 h (n = 10) and 2 h (n = 10), respectively. In I/R group, after ischemia for 1 hour, the clamp was removed and reperfused for 1 hour (n = 10). The same time interval of SMA was taken as SO group (n = 10). Immediately after the establishment of the animal model, PAI examination was performed. After PAI examination, the small intestine was collected for histopathology.Results: The PAI derived parameters of 2 h ischemia group were significantly different from those of SO group and I/R group (P < 0.05). The levels of Hb, HbR, map760 and map 840 were increased in different degrees in ischemia group, especially in 2 h ischemia group (compared with SO group, P < 0.01). With the prolongation of ischemia time, the injury was aggravated. In immunohistochemistry, compared with SO group, BAX increased significantly in 2 h ischemia group (P < 0.01). Similarly, Caspase-3 was significantly higher than the baseline level (P < 0.05). The level of HIF-1a increased in 2 h ischemia group and I/R group (P < 0.05). TUNEL staining showed that the number of apoptotic positive nuclei in 2 h ischemia group was significantly higher than that in SO group (P < 0.05). HE staining showed that ischemia for 2 hours was the most serious, with obvious mucosal damage, extensive epithelial injury and bleeding.Conclusions: PAI can be used as an effective tool to detect acute intestinal ischemia injury and quantitatively evaluate tissue viability.

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Intraperitoneal Mesalamine Does Not Restores Mesenteric Perfusion or Prevent Mucosal Injury Following Intestinal Ischemia and Reperfusion

Proceedings of IMPRS ◽

10.18060/23512 ◽

2019 ◽

Vol 2 (1) ◽

Author(s):

Thomas Knowles ◽

Brian Hosfield ◽

Chris Shelley ◽

Troy Markel

Keyword(s):

Intestinal Ischemia ◽

Cell Damage ◽

Acute Mesenteric Ischemia ◽

Mucosal Injury ◽

Laser Doppler ◽

Cellular Damage ◽

Midline Laparotomy ◽

Intestinal Necrosis ◽

Mesenteric Perfusion ◽

Sudden Decrease

Background and Hypothesis: Acute Mesenteric Ischemia (AMI) is characterized by a sudden decrease in blood flow to varying segments of the small intestine. It can lead to cellular damage, life-threatening intestinal necrosis and, if corrected, subsequent reperfusion injury. Reducing inflammation is key to preventing further cell damage. We therefore hypothesized that administration of mesalamine prior to intestinal ischemia would reduce epithelial cell damage by I/R and restore mesenteric perfusion. Project Methods: C57Bl6J wild type (WT) mice were assigned to mesalamine or vehicle treatment groups (N=8/group). Prior to surgery, mice underwent intraperitoneal injection of treatment. Midline laparotomy was performed. Intestines were eviscerated, superior mesenteric artery (SMA) located, and baseline intestinal perfusion determined using Laser Doppler. SMA was then occluded to induce intestinal ischemia for sixty minutes, thereafter the occlusion was removed. Mesenteric reperfusion was then determined by Laser Doppler. Midline incisions were reapproximated with suture and animals were allowed to recover. After twentyfour hours, animals were re-anesthetized and underwent final assessment of mesenteric perfusion by Laser-Doppler. Animals were then euthanized, and intestines explanted. A portion of tissue was snap frozen for assessment for proinflammatory cytokines by ELISA. Another portion of tissue was stained with H&E and scored for intestinal mucosal injury. Data were assessed for normalcy and compared by Mann-Whitney-U test. P<.05 was significant. Results: Preliminary data suggests mesalamine treated mice show no significant change in mortality compared to vehicle. Mesalamine treated mice also show an insignificant increase in histological damage score. Despite this, they show an insignificant improvement in oxygen perfusion. Conclusion: Intraperitoneal mesalamine administration does not appear to be a useful method for limiting cell damage in GI diseases associated with AMI such as necrotizing enterocolitis. A larger sample size is needed to further elucidate treatment effects.

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