What is the relationship between intracellular cation levels and the resting membrane potential?

What is the relationship between intracellular cation levels and the resting membrane potential?

• A. Intracellular cation levels do not affect RMP.
• B. More intracellular cations lead to a more negative RMP (hyperpolarization).
• C. RMP becomes more variable.
• D. More intracellular cations lead to a more positive RMP (hypopolarization).

Answer: (D)

Resting membrane potential is set by the balance of ionic gradients and the membrane’s permeability, with the inside normally being negative because positive charges tend to leak out more than they leak in. If you increase the amount of positive charge inside the cell, the electrical difference across the membrane becomes less negative, so the membrane potential shifts toward a more positive value. In other words, more intracellular cations cause depolarization, moving the RMP in a positive direction. The idea that intracellular cations have no effect or that they make the inside more negative goes against how the charge separation determines the resting potential.

Resting membrane potential is set by the balance of ionic gradients and the membrane’s permeability, with the inside normally being negative because positive charges tend to leak out more than they leak in. If you increase the amount of positive charge inside the cell, the electrical difference across the membrane becomes less negative, so the membrane potential shifts toward a more positive value. In other words, more intracellular cations cause depolarization, moving the RMP in a positive direction. The idea that intracellular cations have no effect or that they make the inside more negative goes against how the charge separation determines the resting potential.