What is the sarcolemma of a resting muscle fiber is most permeable to?

The sarcolemma of a resting muscle fiber is most permeable to potassium ions (K+). This permeability is primarily due to the presence of potassium leak channels, which allow K+ to flow out of the cell, contributing to the resting membrane potential. In contrast, the sarcolemma is less permeable to sodium ions (Na+), which helps maintain the negative charge inside the cell at rest.