A. Jensen1, N. Drucker1, S. Khaneki1, T. Markel1 1Indiana University School Of Medicine,Surgery,Indianapolis, IN, USA
Introduction: Hydrogen Sulfide (H2S) is an endogenous gasotransmitter that has recently been found to exert beneficial vasodilatory properties. Therefore, hydrogen sulfide may be a novel therapeutic option in the setting of intestinal ischemia and reperfusion injury (I/R). We hypothesized that: 1) H2S would improve post-ischemic mesenteric perfusion and preserve intestinal histological architecture compared to vehicle following intestinal I/R, and 2) the benefits of H2S therapy would be mediated through nitric oxide dependent pathways.
Methods: Adult male C57Bl6J wild type (WT) and eNOS KO (eNOS KO) mice were anesthetized with isoflurane and a midline laparotomy was performed. The intestines were eviscerated, the small bowel mesenteric root identified, and baseline intestinal perfusion was determined using Laser Doppler Imaging. Intestinal ischemia was established by temporarily occluding the superior mesenteric artery for 60 minutes with a non-crushing vascular clamp. Following ischemia, the clamp was removed and the intestines were allowed to recover. Prior to abdominal closure, 250ul of 200nM sodium hydrosulfide (NaHS; an H2S donor) or 250ul of PBS vehicle was injected into the peritoneum. Animals were allowed to recover for 24 hours after which time they were reanesthetized and their mesenteric perfusion reassessed. Perfusion was expressed as percentage of baseline. Following perfusion analysis, animals were sacrificed and intestines explanted and preserved in 4% paraformaldehyde. Intestinal segments were paraffin embedded, sectioned, and stained with H&E. Sections were then graded based on a previously reported histologic injury scale. Perfusion and histology scores were compared using Mann-Whitney test. P-values less than 0.05 were significant.
Results:Hydrogen sulfide improved mesenteric perfusion (WT I/R + NaHS 71.0±6.6%, WT I/R + Vehicle 25.6±6.0%, p<0.01 (A)) following intestinal ischemia and reperfusion injury. In the setting of eNOS ablation, there was no improvement in mesenteric perfusion (eNOS KO I/R + 200nM NaHS 24.7±5.4%, eNOS KO I/R + Vehicle 32.5±8.1%, p=0.59, (A)). Histology injury scores were markedly improved in hydrogen sulfide treated WT animals (WT I/R + 200nM NaHS 1.1±0.3 vs. WT I/R + Vehicle 3.5±0.4, p<0.01(B)). Additionally there was no improvement in histology injury scores in the setting of eNOS ablation (eNOS I/R + 200nM NaHS 2.7±0.2 vs. eNOS KO I/R + Vehicle 2.7±0.3, p=0.84(B)).
Conclusion:The use of hydrogen sulfide following intestinal I/R improves mesenteric perfusion and intestinal histology. The benefits of H2S therapy appear to be mediated through nitric oxide dependent pathways. Further studies are needed to define what other downstream mediators may be involved with hydrogen sulfide therapy prior to widespread clinical implementation.
