Changes in fluid composition on the serosal surface of jejunum and small colon subjected to venous strangulation obstruction in ponies.

The research investigates changes in fluid composition on the surface of the jejunum and small colon of anesthetized ponies when they are subjected to venous strangulation obstruction (VSO) for 3 and 6 hours. The research found that despite the development of severe mucosal lesions during VSO, bacteria did not cross the intestinal wall and the surrounding fluid showed significant changes in certain chemical properties.

Research Methodology

• In the research, six anesthetized ponies were used as subjects.
• Three segments each of their jejunum and small colon were isolated in plastic bags filled with Hanks’ balanced salt solution.
• One jejunal and one small colon segment were subjected to venous strangulation obstruction (blocking of blood flow) for three hours (VSO-3), some for six hours (VSO-6), and a 6-hour sham procedure was followed to control changes due to isolation in the plastic bag.
• Additional segments of jejunum and colon, which were not placed in bags, served as controls for histological examination and collagenase measurements.
• Samples of the fluid surrounding the intestine were collected for chemical analyses, nucleated cell count, aerobic and anaerobic bacteriologic culture, and measurement of collagenase activity.
• Full-thickness tissue samples were collected for histological examination and collagenase content measurement.

Research Findings

• The researchers report that bacteria did not cross the intestinal wall after 3 and 6 hours of VSO, despite severe mucosal lesions present in these segments.
• At 6 hours, the PO2 level was significantly less and the PCO2 level significantly higher in the fluid surrounding the VSO-6 jejunal segments, as compared to the sham jejunal segments.
• The pH was significantly lower in the fluid surrounding VSO-6 small colon segments, compared to the sham colon segments after 6 hours.
• For both jejunum and small colon, the levels of phosphate and lactate were significantly higher in the VSO-6 fluid than in the corresponding sham fluids, after 6 hours.
• Fibrin was formed around all VSO segments, even though fibrinogen was not detected in the surrounding fluid; this suggested a possible rapid conversion of fibrinogen to fibrin.