The effect of ischaemic postconditioning on mucosal integrity and function in equine jejunal ischaemia

Verhaar, Nicole; Breves, Gerhard; Hewicker‐Trautwein, M.; Pfarrer, Christiane; Rohn, Karl; Burmester, Marion; Schnepel, Nadine; Neudeck, Stephan; Twele, Lara; Kästner, Sabine

doi:10.1111/evj.13450

Cited by 7 publications

(6 citation statements)

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“…Quantification of blood flow by Laser Doppler fluxmetry can be used to determine the local microcirculation in the intestinal wall [ 5 , 6 , 15 , 28 ], which is an advantage compared to measuring the macrocirculation based on Doppler sonography [ 12 , 17 , 19 ] or via blood pressure measurement [ 9 ] in the mesenteric blood vessels. Nevertheless, the intestinal hypermotility seen following the induction of ischaemia led to severe motion artefacts in Laser Doppler fluxmetry measurements.…”

Section: Discussionmentioning

confidence: 99%

“…The Ussing chamber experiment was performed as previously described [ 6 , 27 ]. In brief, the mucosa was manually stripped of the seromuscular layer and mounted in Ussing chambers, with 1.13 cm 2 of tissue exposed.…”

Section: Methodsmentioning

confidence: 99%

“…In small intestinal ischaemia models, segmental jejunal ischaemia has been created by occluding the mesenteric vessels with ligatures [ 3 , 4 , 5 , 6 , 7 ] or haemostatic clamps [ 8 , 9 , 10 , 11 ]. For the duration of ischaemia, 90 to 120 min has frequently been elected [ 5 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ].…”

Section: Introductionmentioning

confidence: 99%

“…Monitoring blood flow before and after induction of ischaemia and at the onset of reperfusion is of great importance to ensure that the previously defined ischaemia is achieved in all subjects, thereby warranting comparable and reproducible results [ 21 ]. Previous studies have used surface oximetry [ 8 ], Doppler sonography [ 9 , 17 ], blood pressure measurement [ 9 ], Laser Doppler fluxmetry (LDF) [ 19 ] or LDF in combination with microlightguide spectrophotometry (MS) [ 5 , 6 , 15 ]) for this purpose.…”

Section: Introductionmentioning

confidence: 99%

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Low Flow versus No Flow: Ischaemia Reperfusion Injury Following Different Experimental Models in the Equine Small Intestine

Grages

Verhaar

Pfarrer

et al. 2022

Animals

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In experimental studies investigating strangulating intestinal lesions in horses, different ischaemia models have been used with diverging results. Therefore, the aim was to comparatively describe ischaemia reperfusion injury (IRI) in a low flow (LF) and no flow (NF) model. Under general anaesthesia, 120 min of jejunal ischaemia followed by 120 min of reperfusion was induced in 14 warmbloods. During ischaemia, blood flow was reduced by 80% (LF, n = 7) or by 100% (NF, n = 7). Intestinal blood flow and oxygen saturation were measured by Laser Doppler fluxmetry and spectrophotometry. Clinical, histological, immunohistochemical and Ussing chamber analyses were performed on intestinal samples collected hourly. Tissue oxygen saturation was significantly lower in NF ischaemia. The LF group exhibited high variability in oxygen saturation and mucosal damage. Histologically, more haemorrhage was found in the LF group at all time points. Cleaved-caspase-3 and calprotectin-stained cells increased during reperfusion in both groups. After NF ischaemia, the tissue conductance was significantly higher during reperfusion. These results aid in the selection of suitable experimental models for future studies. Although the LF model has been suggested to be more representative for clinical strangulating small intestinal disease, the NF model produced more consistent IRI.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Low Flow versus No Flow: Ischaemia Reperfusion Injury Following Different Experimental Models in the Equine Small Intestine

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Verhaar

Pfarrer

et al. 2022

Animals

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“…Comparing this to the timing of HIF1α expression as reported in the literature, intestinal protein levels have been shown to be increased at 2-12 h following hypoxia (17, 26, 36). The histomorphological examination of these samples showed a significant degree of epithelial separation and hemorrhage during ischemia, that did not progress significantly during reperfusion (27). Relating these findings to the HIF1α immunoreactivity, this indicates that the first occurrence of histomorphological mucosal damage at ischemia does not necessarily correlate with an increase in enterocyte HIF1α immunoreactivity seen at reperfusion.…”

Section: Figurementioning

confidence: 73%

Hypoxia signaling in the equine small intestine: Expression and distribution of hypoxia inducible factors during experimental ischemia

Verhaar

Buhr²,

Köckritz-Blickwede³

et al. 2023

Front. Vet. Sci.

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IntroductionHypoxia inducible factors (HIF) are widely researched in human medicine for their role in different disease processes. The aim of this study was to investigate the expression and distribution of HIF in experimental small intestinal ischemia in the horse.MethodsIn 14 horses under general anesthesia, segmental jejunal ischemia with 90% reduction in blood flow was induced. The horses were randomly divided into two groups of seven horses, one subjected to ischemic postconditioning (IPoC) by delayed reperfusion, and a control group (group C) undergoing undelayed reperfusion. Intestinal samples were taken pre-ischemia, after ischemia and after reperfusion. Following immunohistochemical staining for HIF1α and -2α, the immunoreactivity pattern in the small intestine was evaluated by light microscopy, and the mucosal enterocyte and muscularis staining were semi-quantitatively scored. Additionally, mucosal HIF1α protein levels were determined by an Enzyme Linked Immunosorbent Assay (ELISA), and mRNA levels of HIF1α and its target genes by a two-step real-time Reverse Transcriptase Polymerase Chain Reaction. Statistical comparison was performed between the groups and time points using parametric and non-parametric tests (p < 0.05).ResultsAll cell types exhibited cytoplasmic and nuclear immunoreactivity for HIF1α. After reperfusion, the cytoplasmic staining of the crypt and villus enterocytes as well as the villus nuclear staining significantly increased, whereas the perinuclear granules in the crypts decreased. The protein levels showed a significant decrease in group C at reperfusion, with lower HIF1α levels in group C compared to group IPoC during ischemia and reperfusion. No other group differences could be detected. In the HIF2α stained slides, mild to moderate cytoplasmic staining yet no nuclear immunoreactivity of the enterocytes was observed, and no significant changes over time were noted.Discussionthe changes in HIF1α immunoreactivity pattern and expression over time suggest that this transcription factor plays a role in the intestinal response to ischemia in horses. However, the current study could not identify an effect of IPoC on HIF distribution or expression.

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Flowmetry and spectrophotometry for the assessment of intestinal viability in horses with naturally occurring strangulating small intestinal lesions

Verhaar,

Grages,

Bienert‐Zeit

et al. 2024

Equine Veterinary Journal

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BackgroundAncillary diagnostic methods to enhance the accuracy of viability assessment have not been established for use in clinical practice.ObjectivesTo assess intestinal microperfusion measured by Laser Doppler Flowmetry and Spectrophotometry (LDFS) in naturally occurring small intestinal strangulations of different origins and to compare this between viable and non‐viable segments.Study designProspective clinical trial.MethodsForty horses undergoing colic surgery for naturally occurring small intestinal strangulations were included. Tissue oxygen saturation (tSO2), haemoglobin (tHB) and blood flow (tBF) were determined by LDFS before and after release of the strangulation. Intestinal biopsies were taken in cases that underwent intestinal resection or intraoperative euthanasia and assessed using a semi‐quantitative mucosal injury score (MIS). The LDFS measurements were compared between the different categories of strangulation causes and histopathological injury using parametric and non‐parametric tests (p < 0.05).ResultsStrangulations by pedunculated lipomas had lower tBF (13.9 ± 18 arbitrary units [AU]) than epiploic foramen entrapments (65.2 ± 61 AU; CI −1.697 to −0.2498; p = 0.005). Segments with MIS > 5 showed lower tBF during strangulation than segments with MIS < 4 (mean difference 61.1 AU; CI −1.119 to −0.07361; p = 0.03). This did not differ significantly following release of strangulation. Furthermore, there was a positive correlation between the inflammatory cell count and tBF during strangulation (r 0.34; CI 0.01 to 0.60; p = 0.04). The tSO2 and tHB did not differ between the different categories of lesions or injury.Main limitationsNo biopsies could be taken from the intestinal segments that did not undergo resection. The duration of strangulation could not reliably be ascertained.ConclusionsBlood flow measurements in naturally occurring strangulating lesions show a varying degree of ischaemia in different causes of strangulation. Intestinal blood flow measurements prior to release of the strangulation could potentially contribute to the identification of mucosal injury, yet a high individual variability and other contributing factors need to be considered.

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The effect of ischaemic postconditioning on mucosal integrity and function in equine jejunal ischaemia

Abstract: This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

Cited by 7 publications

References 30 publications

Low Flow versus No Flow: Ischaemia Reperfusion Injury Following Different Experimental Models in the Equine Small Intestine

Low Flow versus No Flow: Ischaemia Reperfusion Injury Following Different Experimental Models in the Equine Small Intestine

Hypoxia signaling in the equine small intestine: Expression and distribution of hypoxia inducible factors during experimental ischemia

Flowmetry and spectrophotometry for the assessment of intestinal viability in horses with naturally occurring strangulating small intestinal lesions

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