As a subject matter expert in the field of medical physiology, I can explain the mechanism by which hyperkalemia leads to depolarization. In a normal state, the resting membrane potential of a cell is maintained by the difference in charge across the cell membrane, which is primarily due to the high concentration of potassium ions (K+) inside the cell compared to the outside. This is known as the Nernst equation, which describes the equilibrium potential for K+ ions. Hyperkalemia is a condition where there is an abnormally high concentration of potassium in the blood. When this occurs, the concentration gradient of potassium across the cell membrane decreases. As a result, the cell's membrane potential shifts closer to the equilibrium potential for potassium, which is more positive than the normal resting membrane potential. Depolarization is the process where the cell membrane potential moves from its resting state towards a less negative (or more positive) value. In the context of hyperkalemia, the reduced concentration gradient for potassium ions means that there is less of a driving force for potassium to stay inside the cell. This leads to a higher concentration of potassium outside the cell relative to the inside, which causes the membrane potential to become less negative (or more positive), thus depolarizing the cell. This depolarization can have significant effects on the function of cells, particularly muscle cells and neurons. For example, in the heart, depolarization is a critical step in the initiation and conduction of the electrical impulses that cause the heart to contract. Hyperkalemia can disrupt this process, leading to cardiac arrhythmias or even cardiac arrest. read more >>

Increased extracellular potassium levels result in depolarization of the membrane potentials of cells due to the increase in the equilibrium potential of potassium. This depolarization opens some voltage-gated sodium channels, but also increases the inactivation at the same time.read more >>