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Correct me where/if I am wrong: At rest, ionic channels in a neuron are closed, except for leakage (like with CL- ions) for instance. So I'd assume that the equilibrium (or reversal) potential for CL- ions should be the same as the rest potential otherwise there'd be constant flow of ions in the cell and the potential would change. Unless this flow is compensated by ionic pumps, but as far as I know these are too slow for that.

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"Leak" is used to refer to two different things. For one of them, the answer is "no", for the other, the answer is "yes, tautologically".


Two-pore potassium channels are also called "leak channels". These channels mediate inward-rectifying potassium (primarily) conductances, and contribute strongly to the resting potential because they are one of the few types of channels that are fairly open at rest. The reversal potential for these channels is going to be basically the reversal potential for potassium, though, not the resting potential.


The other meaning for "leak" is basically "every conductance at rest that isn't voltage-gated". It's more of a non-specific fudge factor, a mathematical accounting for all the things that don't change (or don't change much) during an action potential. It arises as a necessary part of the Hodgkin-Huxley model to set the resting potential and return to baseline after an action potential.

It's not necessary to specify the identity of the "leak" for the math to work, and Hodgkin and Huxley didn't know much about it. But, besides minor conductances from voltage gated channels at rest, in the Hodgkin and Huxley model the resting potential is primarily determined by this abstract "leak".


It's important to note that similarity of resting potential to the chloride reversal potential is mostly coincidental; yes there can be some chloride leak at rest, but the actual leak is mostly potasssium (those two-pore channels) and a combination of other things including sodium. The difference between the resting potential and the potassium reversal potential means that yes, at rest neurons are constantly leaking ions and need constant pumping to keep ion concentrations stable. However, the magnitude of the leak is fairly small, so think of it more like a slow drip than a flood.

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