Effects of in vivo lidocaine administration at the time of ischemia and reperfusion on in vitro contractility of equine jejunal smooth muscle.

This study examines whether the administration of lidocaine during episodes of reduced blood flow (ischemia) and following its restoration (reperfusion) in horses can achieve sufficient concentrations in smooth muscle to protect against the adverse effects of ischemia-reperfusion injury on the movement of the muscles.

Research Methods and Procedures

• The study involved twelve horses, divided into two groups selected for treatment instances: one with lidocaine administration during ischemia (IRL), and another group where ischemia was induced without any lidocaine treatment (IR).
• Artificial ischemia (restriction of blood supply) and reperfusion (restoration of blood supply) injury to the horse’s jejunal segments (part of the small intestine) were induced in conjunction with the above-stated treatments.
• The performance of the isometric force in the smooth muscle preparations from both these horse groups was measured, with and without the application of lidocaine in the lab.
• Lidocaine concentrations in the smooth muscle were determined using high-performance liquid chromatography (HPLC), a technique for separating mixtures of chemicals into respective individual compounds.
• To examine lidocaine’s impact on the permeability of the cell membrane in the muscle, the researchers measured the activity of two enzymes, creatine kinase and lactate dehydrogenase, released during in vitro incubation.

Findings

• The study found that administering lidocaine in vivo (in the living organism) during ischemia and reperfusion could maintain the muscle’s ability to contract after the injury.
• More specifically, the researchers discovered that the basic contractility (ability to contract) and frequency of contractions in the smooth muscle tissues increased significantly in the case of IRL smooth muscle tissues being cultured in vitro (in the lab).
• Furthermore, the application of lidocaine in vitro also improved the contraction of smooth muscle preparations from both IR and IRL groups more.
• However, only the in vitro application of lidocaine was found to improve membrane permeability in the smooth muscle from both IR and IRL preparations.
• Lidocaine could be measured in the in vivo treated samples, indicating its accumulation in the muscle tissues and serum.

Conclusions

• In conclusion, the study showed that the administration of lidocaine during the occurrence of ischemia and subsequent reperfusion had positive outcomes on the smooth muscle’s motility in horses.
• If initiated during surgery to treat colic (abdominal pain) in horses, lidocaine treatment may enhance its prokinetic features (improving gastrointestinal motility) by protecting the smooth muscle from the harmful effects caused by ischemia and subsequent reperfusion.