Failure to demonstrate reperfusion injury following ischaemia of the equine large colon using dimethyl sulphoxide.

This study focused on monitoring the incidence and mechanisms of reperfusion injury in horses’ large intestine after a duration of blood flow obstruction (either haemorrhagic strangulation obstruction or ischaemic strangulation obstruction). It also assessed the influence of dimethyl sulphoxide (DMSO) treatment, concluding that no reperfusion injury was detected following a 60-minute ischaemic period, even with the DMSO treatment administered.

Study Design and Procedure

• The researchers designed the experiment using four groups of horses, each group consisting of four subjects. The obstructions, either ischaemic strangulation obstruction (ISO) or haemorrhagic strangulation obstruction (HSO), were created 40 cm from the pelvic flexure and held in place for 60 minutes under general anaesthesia.
• Either normal saline or a 20% DMSO solution was administered intravenously to the equine subjects 10 minutes before the cessation of the ischaemic period. The DMSO dosage equated to 1 gram per kilogram of the horse’s body weight.
• Intestinal wall biopsies, as well as right colic arterial and venous blood samples, were taken at intervals of 0, 60, 90, and 120 minutes following the creation of the obstructions.

Data Collection and Analysis

• Histological evaluation of the intestine was performed using haematoxylin and eosin stained sections and immunohistochemical staining for albumin.
• Mucosal and serum levels of reduced glutathione (GSH) and oxidised glutathione (GSSG), in addition to the amount of lymphatic dilatation with albumin and submucosal pooling of albumin, were used as indirect measures of oxygen free radical production.
• These markers were chosen because they are known indicators of oxidative stress, which is often a precursor to reperfusion injury.

Findings and Conclusion

• Histopathological changes were observed to be minimal after 1 hour of either obstruction type. During the post-ischaemic period, changes were still minimal for ISO and only moderate for HSO.
• Serum GSH and GSSG levels were undetectable, indicating minimal oxidative stress.
• The administration of DMSO did not show any noticeable benefit when assessed by histology, immunohistochemistry, or the preservation of GSH levels in the mucosa.
• Overall, the study concluded that no reperfusion injury could be detected following 60 minutes of ischaemia, regardless of obstruction type or treatment with DMSO.