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. Author manuscript; available in PMC: 2011 Apr 1.
Published in final edited form as: Nat Neurosci. 2010 Sep 19;13(10):1249–1256. doi: 10.1038/nn.2643

Figure 4. DAMGO inhibits N-type currents similarly in nociceptors from all three genotypes.

Figure 4

Representative currents from nociceptors isolated from WT (a), b*b (b), and aa* (c) mice show the inhibitory actions of a saturating concentration of 10 μM DAMGO on calcium currents in the absence (left; whole cell currents) and presence (right; non-N-type currents) of ω-Ctx GVIA (2 μM). For comparison, current amplitudes are scaled relative to their respective controls (a–c). Currents were elicited by test pulses to 0 mV from a holding potential of − 80 mV. Scale bar corresponds to 5 ms. Average % inhibition by DAMGO in nociceptors of WT, b*b, and aa* mice in the absence (d; whole cell current) and presence (e; non-N-type current) of 2 μM ω-Ctx GVIA. Values shown are means ±s.e.m. n values are number of cells, all data sets contain recordings from at least 9 mice. DAMGO was significantly less effective at inhibiting whole cell currents in aa* mice compared to WT (d; P = 0.0432). DAMGO’s inhibition of N-type currents in nociceptors compared among the three genotypes (f). For comparison, because N-type current density was significantly smaller in nociceptors of aa* mice, ,% inhibition by DAMGO was normalized to N-type current density as follows: {[(Icontrol−IDAMGO)whole cell − (ICtx − IDAMGO)non-N-type]/IN-type} × 100%. Average values of ICtx, IDAMGO, and IN-type were obtained from nociceptors of WT (n = 8), b*b (n = 10), aa* (n = 9) mice for these calculations.