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Increased extrajunctional acetylcholine sensitivity produced by chronic acetylcholine sensitivity produced by chronic
The Journal of Physiology
|January 1, 1975
Summary
Chronic muscle paralysis in rats leads to increased extrajunctional acetylcholine sensitivity, mimicking denervation effects. Muscle activity appears to control this sensitivity in neuromuscular junctions.
Area of Science:
- Neuroscience
- Muscle Physiology
- Pharmacology
Background:
- Neuromuscular blockade is used therapeutically but can induce changes in muscle.
- Understanding how muscle inactivity affects neuromuscular junctions is crucial.
Purpose of the Study:
- To investigate the effects of chronic neuromuscular paralysis on rat muscle.
- To determine if muscle activity regulates extrajunctional acetylcholine sensitivity.
Main Methods:
- Rats were pharmacologically paralyzed using D-tubocurarine, succinylcholine, or alpha-bungarotoxin for up to 3 days.
- Electrophysiological recordings assessed neuromuscular transmission, miniature end-plate potentials, resting potentials, and input resistance.
- Binding of [125-I]-alpha-bungarotoxin and sensitivity to acetylcholine were measured in muscle fibers.
Main Results:
- Paralysis for 3 days increased extrajunctional alpha-bungarotoxin binding and acetylcholine sensitivity, similar to denervation.
- Neuromuscular transmission and function were restored after drug removal.
- Muscle fiber properties and acetylcholinesterase levels were largely unaffected by paralysis.
Conclusions:
- Chronic neuromuscular paralysis induces changes in muscle fiber properties that resemble denervation.
- Muscle activity is a key regulator of extrajunctional acetylcholine sensitivity.