Question

Suppose a drug is developed that blocks K+ leakage channels. The drug prevents ions from passing through those channels. If this drug was applied to a neuron, what would be the most immediate effect on that neuron?
1. The resting membrane potential would become less negative (more positive).
2. The resting membrane potential would become more negative.
3. The concentration gradient for Na+ would decrease.
4. The concentration gradient for K+ would decrease.

Answer 1

Answer: 1. The resting membrane potential would become less negative (more positive).

Explanation:

Resting membrane potential is a voltage carried by a resting (non-signaling) neuron, or called as resting potential, across its membrane.  The resting potential is determined by ion concentration gradients across the membrane, and the permeability of the membrane to each ion form.  

In a resting brain, there are gradients of concentration across the Na+ and K+ membranes. Forces shift their gradients down through channels, resulting in a separation of charges that provides the potential for rest. The membrane is much more permeable to K+ than to Na+, so the resting potential is similar to K+'s potential for equilibrium.

Hence, the correct option is 1. The resting membrane potential would become less negative (more positive).