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. Author manuscript; available in PMC: 2011 May 3.
Published in final edited form as: J Physiol Paris. 2009 Nov 23;104(3-4):203–214. doi: 10.1016/j.jphysparis.2009.11.017

Figure 6. Effect of Dopamine on Club ending repetitive firing and near-threshold membrane responses.

Figure 6

A, Firing responses evoked by a depolarizing current pulse (3 nA, 50 ms duration) before (left) and after (right) extracellular application of 100 μM Dopamine. B, Near-threshold voltage response (2 nA, 50 ms duration) obtained before and after Dopamine application. The characteristic initial non-linear membrane response in the form of an apparent increase in the slope resistance, attributed to the activation of INa+P (Curti and Pereda, 2004; Curti et al, 2008) was substantially reduced by application of Dopamine, suggesting the down-regulation of INa+P by this modulator. C, This effect was quantified by comparing the ratio between early and late responses during control conditions and after Dopamine application. This ratio, estimated as (ΔV early − ΔV late)/ΔV early, averaged 0.33 ± 0.12 in control, and was significantly affected by dopamine application averaging 0.15 ± 0.05 (mean ± S.D.; p= 0.0002; n=8).