Skeletal muscle resting membrane potential in potassium deficiency

Area of Science:

• Physiology
• Muscle Biology
• Electrophysiology

Background:

• Resting transmembrane potential (E(m)) of skeletal muscle is linked to intracellular and extracellular potassium concentrations ([K(i)]/[K(o)]).
• Potassium deficiency theoretically predicts a rise in E(m) due to disproportionately smaller intracellular potassium decrease.
• Kaliopenic myopathy involves muscle dysfunction associated with low potassium levels.

Purpose of the Study:

• To investigate the theory predicting E(m) changes in potassium deficiency.
• To characterize E(m) in dogs and rats experiencing kaliopenic myopathy.
• To explore the role of altered muscle membrane function in kaliopenic myopathy.

Main Methods:

• Measured muscle composition and E(m) in dogs during moderate and severe potassium deficiency.
• Compared measurements with severely potassium-deficient rats.
• Utilized the Goldman equation for theoretical E(m) predictions.

Main Results:

• E(m) rose in moderately potassium-deficient dogs and severely deficient rats, aligning with theoretical predictions.
• Severe potassium deficiency in dogs caused a significant decline in E(m) to -55 mV.
• Muscle paralysis occurred in severely potassium-deficient dogs, but not in rats.

Conclusions:

• The observed decline in E(m) during severe potassium deficiency in dogs correlates with paralysis.
• Altered muscle membrane function likely contributes to kaliopenic myopathy and paralysis in dogs.
• This membrane dysfunction may explain exercise-induced muscle necrosis in potassium-deficient dogs.