Tugging force: A new objective index for evaluating acute changes in neuromuscular function in mice

Area of Science:

• Pharmacology
• Neuroscience
• Physiology

Background:

• Muscle relaxants and other agents significantly impact neuromuscular function.
• Existing in vitro and in situ methods lack convenience for studying acute neuromuscular effects in conscious mice.
• A need exists for a practical device to assess the time course of neuromuscular changes.

Purpose of the Study:

• To develop and validate a novel device and parameter for measuring neuromuscular performance in conscious mice.
• To assess the time course and dose-dependency of acute neuromuscular changes induced by muscle relaxants.

Main Methods:

• A two-compartment device was designed with a chamber and a narrow tunnel.
• Mice were trained to enter the tunnel, and tugging force was measured using a string attached to the tail.
• Neuromuscular function was assessed by measuring the peak tugging force after administration of muscle relaxants.

Main Results:

• Administration of suxamethonium, vecuronium, and pancuronium led to a maximal decrease in peak tugging force within 3-5 minutes.
• Neuromuscular function recovered within 20 minutes post-administration.
• The observed responses to muscle relaxants were dose-dependent.

Conclusions:

• Tugging force provides an objective and reproducible parameter for evaluating acute changes in neuromuscular function.
• The developed device offers a convenient method for studying the time course of neuromuscular effects in conscious mice.