Microvascular permeability and endothelial cell morphology associated with low-flow ischemia/reperfusion injury in the equine jejunum.
Authors: Dabareiner, Snyder, White, Pascoe, Harmon, Gardner, Woliner, Pinney, Sullins
Journal: American journal of veterinary research
Summary
# Editorial Summary: Ischaemia/Reperfusion Injury and Microvascular Permeability in Equine Jejunum Intestinal ischaemia-reperfusion (I/R) injury represents a critical pathophysiological consequence of colic and surgical intervention in horses, yet the mechanisms underlying post-ischaemic tissue damage remain incompletely understood. Dabareiner and colleagues used an experimental model combining haemodynamic measurements, lymphatic analysis, and histological examination to quantify changes in microvascular permeability in eight horses subjected to 60 minutes of controlled low-flow ischaemia (25% baseline blood flow) followed by reperfusion. The osmotic reflection coefficient—a measure of the microvascular barrier's ability to restrict protein passage—increased markedly from 0.19 in normal jejunum to 0.48 following I/R injury, indicating substantially compromised endothelial selectivity; this was accompanied by significant capillary endothelial cell ultrastructural damage and oedema in both submucosal and serosal layers. These findings demonstrate that I/R injury fundamentally disrupts the intestinal microvascular barrier function, a mechanism that likely perpetuates mucosal dysfunction, systemic endotoxin translocation, and the cascade of post-colic complications—knowledge that informs both surgical decision-making regarding ischaemia duration and post-operative management strategies aimed at minimising secondary injury.
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Practical Takeaways
- •Intestinal ischemia/reperfusion injuries cause significant microvascular permeability changes that lead to tissue edema; recognizing early signs of reduced mesenteric blood flow is critical for intervention
- •The degree of endothelial damage correlates with microvascular leakage, suggesting that aggressive fluid resuscitation and management of reperfusion injury are essential in colic cases with compromised blood flow
- •Understanding the timeline and mechanisms of microvascular injury can help guide treatment decisions in post-operative colic cases where intestinal viability is compromised
Key Findings
- •Osmotic reflection coefficient increased significantly from 0.19 ± 0.06 in normal jejunum to 0.48 ± 0.05 after 60 minutes of ischemia (25% baseline flow) and reperfusion (P ≤ 0.0001)
- •Ischemia/reperfusion injury caused significant increases in submucosal and serosal tissue volume consistent with edema (P ≤ 0.0001)
- •Transmission electron microscopy revealed capillary endothelial cell damage in horses undergoing ischemia/reperfusion injury
- •Increased microvascular permeability was demonstrated by filtration-independent lymph flow rate analysis at venous pressure of 30 mm Hg