S. Khaneki1, A. Jensen1, N. Drucker1, T. Markel1 1Indiana University School Of Medicine,Surgery,Indianapolis, IN, USA
Introduction: Direct peritoneal resuscitation (DPR) has been shown to increase survival following intestinal ischemia and reperfusion injury (I/R). We have previously appreciated that the use of minimal essential medium (MEM) contributes to these survival benefits as well as a reduction in intestinal inflammation. We hypothesized that: 1) DPR using MEM as a dialysate would increase mesenteric perfusion following intestinal I/R, and 2) increased perfusion would be dependent on endothelial nitric oxide pathways.
Methods: Eight-week-old C57Bl6J wild type (WT) and C57Bl6J eNOS Knock Out (eNOS KO) male mice were anesthetized with isoflurane. A midline laparotomy was performed and the intestines were eviscerated. Baseline perfusion was measured using Laser Doppler Imaging (LDI). Intestinal ischemia was then induced by clamping the superior mesenteric artery (SMA) with a non-traumatic vascular clamp for 60 minutes. Following intestinal ischemia, the clamp was removed and the incision was closed in two layers. Prior to final closure, 1ml of PBS vehicle or 1 ml of MEM (alpha-minimum essential medium plus 16% fetal bovine serum, 1% penicillin/streptomycin, and 1% glutamine) was injected into the abdominal cavity of the WT and eNOS KO groups. Animals were then allowed to recover for 48 hours. After this time, animals were reanesthetized, the midline incision opened, and intestinal perfusion reassessed by LDI. Animals were then euthanized. Perfusion was expressed as a percentage of baseline and was compared between groups using the Mann-Whitney test. A p<0.05 was considered statistically significant.
Results:Direct peritoneal resuscitation with MEM significantly improved mesenteric perfusion compared to PBS as measured by laser doppler imaging (WT + Vehicle: 32.85±17.2% vs. WT + MEM: 105.9±6.58%, p<0.05). The benefits of DPR with MEM were lost when endothelial nitric oxide signaling pathways were ablated (WT + MEM: 105.9±6.58% vs. eNOS KO + MEM: 19.65 ± 5.49%, p<0.05).
Conclusion:Direct peritoneal resuscitation with MEM has significant therapeutic potential for its ability to improve mesenteric perfusion following intestinal ischemia. This benefit appears to be dependent on nitric oxide signaling within the mesenteric endothelium. Further investigation into additional downstream signaling cascades are essential prior to DPR being implemented in human clinical trials.
