Effect of lidocaine on inflammation in equine jejunum subjected to manipulation only and remote to intestinal segments subjected to ischemia.

This research investigated how lidocaine impacts neutrophil infiltration (a sign of inflammation) in a horse’s manipulated intestine and parts of the intestine remote to ischemic areas. The study found that lidocaine did not consistently lower neutrophil infiltration, suggesting its limited impact on inflammation in this context.

Experimental Procedure

• Animals used in this study were 14 healthy horses. All the horses underwent a surgical procedure called ventral midline celiotomy.
• Post-surgery, mild ischemia, a condition of reduced blood flow, was induced in portions of the jejunum and the large colon.
• In a part of the jejunum, manipulation was done by massaging the jejunal wall ten times. During the course of anesthesia, the horses either received lidocaine or a saline solution.
• By getting biopsy specimens at 0, 1, and 4 hours after manipulation and ischemia, researchers could assess tissue injury, neutrophil influx, expression of cyclooxygenase (an enzyme involved in inflammation), and the expression of hypoxia-inducible factor 1α (a transcription factor that responds to reduced oxygen in the cell).
• They also measured transepithelial resistance (TER) and mannitol flux with the help of Ussing chambers. TER is a measure of the intestine’s epithelial barrier function, and mannitol flux measures the permeability of the barrier.

Main Results

• Lidocaine did not consistently decrease neutrophil infiltration in ischemic, manipulated, or control tissues.
• Lidocaine meaningfully reduced circular muscle and overall scores for cyclooxygenase-2 expression in manipulated tissues. Cyclooxygenase-2 is an enzyme that plays a critical role in inflammation, and so this finding suggests lidocaine might have some anti-inflammatory effects.
• Manipulated tissues had significantly less hypoxia-inducible factor 1α expression at 4 hours than control tissues.
• At 4 hours, the mucosa from manipulated and control segments showed lower TER and greater mannitol flux than the control tissues at 0 hours. This indicates that manipulation disturbs the normal functioning of the intestinal barrier.
• Lidocaine did not significantly decrease calprotectin expression. Calprotectin is a protein found in neutrophil cytosol and is often used to assess inflammation in the body.
• The degree of neutrophil infiltration was similar across control, ischemic, and manipulated tissues after 4 hours.

Conclusions and Clinical Relevance

• The study concluded that manipulated jejunum did not have a significantly larger increase in neutrophil infiltration compared with the control (nonmanipulated) jejunum.
• Furthermore, lidocaine did not consistently reduce neutrophil infiltration in the jejunum, implying that it may not be effective at reducing inflammation in these tissues.