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Potassium movements in denervated frog sartorius muscle
The American Journal of Physiology
|March 1, 1985
Summary
Denervation reduces potassium (K+) conductance in frog muscle by decreasing inward rectification and increasing linear channels. This impacts the resting membrane potential and K+ movement across the sarcolemma.
Area of Science:
- Muscle physiology
- Electrophysiology
- Membrane biophysics
Background:
- The sarcolemma's resting membrane potential (VM) is crucial for muscle function.
- Potassium ion (K+) movement significantly influences VM.
- Denervation alters muscle membrane properties.
Purpose of the Study:
- To investigate the effects of denervation on K+ movement and VM in frog sartorius muscle.
- To characterize changes in K+ conductance (gK) components, specifically inward rectification (gIR) and linear channels (gL).
Main Methods:
- Studied K+ movement and VM in normal and denervated frog sartorius muscle preparations.
- Equilibrated muscles in high K+ (100 mM) and Cl- (219 mM) solutions.
- Measured gK, gIR, and gL under varying driving forces for K+.
Main Results:
- Denervation reduced total K+ conductance (gK) from 368 to 282 µS·cm⁻².
- This reduction was due to decreased gIR (359 to 198 µS·cm⁻²) and increased gL (9 to 84 µS·cm⁻²).
- Inward rectifying properties were significantly diminished post-denervation.
Conclusions:
- Denervation alters the composition of resting K+ permeability pathways in frog muscle.
- The inward rectifier channel's function is impaired by denervation, while linear channels become more prominent.
- Denervation may affect the closing mechanism of the inward rectifier channel under outward K+ driving forces.