What is the effect of decreased potassium levels on the rate of depolarization?

Decreased potassium levels, known as hypokalemia, have a significant impact on the electrical activity of cells, particularly in excitable tissues such as cardiac and neural cells. Under normal conditions, potassium ions help to maintain the resting membrane potential and contribute to the process of depolarization, which is critical for the transmission of electrical impulses.

When potassium levels decrease, the resting membrane potential becomes more negative (hyperpolarized), making it more difficult for depolarization to occur. This leads to a reduction in the overall excitability of the cell. As a result, the rate at which depolarization occurs is slowed down. This is particularly important in cardiac myocytes, where a decreased heart rate can result from reduced potassium levels, potentially leading to arrhythmias.

Thus, the impact of decreased potassium levels directly correlates to a reduction in the rate of depolarization, making it clear why this is the correct answer.