Final answer:
Hyperkalemia leads to a decreased membrane potential due to the higher extracellular potassium concentration, which hinders the cells' ability to repolarize after an action potential.
Step-by-step explanation:
The relationship between hyperkalemia and membrane potential is that hyperkalemia causes a decrease in membrane potential. Hyperkalemia is characterized by an elevated potassium (K+) level in the blood, which can lead to excessive potassium in the extracellular fluid (ECF). Because of the increased K+ concentration gradient between the inside and outside of the cell, there will be a tendency for more K+ to remain inside the cell instead of moving out during repolarization, causing the resting membrane potential to be less negative than normal. This reduced gradient affects the cell's ability to repolarize properly after an action potential. For excitable cells, such as neurons and muscle fibers, this means that they are more likely to be closer to the threshold for depolarization and may fire action potentials more readily, which can lead to such symptoms as muscle weakness and cardiac arrhythmias.