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. 2011 Oct 31;589(Pt 24):5965–5986. doi: 10.1113/jphysiol.2011.219378

Figure 5. A background sodium conductance contributes to resting membrane potential.

Figure 5

Effects of substitution of external Na+ with the impermeant ion NMDG+, indicated by the horizontal hatched bar, during perforated patch recordings. TTX at 2 μm is present throughout. A, NMDG+ substitution for Na+ causes hyperpolarization and cessation of action potential generation. B, voltage clamp at the K+ reversal potential reveals a standing inward conductance that is eliminated during NMDG+ substitution. C, CRH/AVP does not rapidly depolarise corticotrophs or stimulate action potential generation in Na+-free external solutions. D, in the mathematical model of a corticotroph, elimination of the background Na+ conductance simulates the recording shown in A.