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Figure 5 | Molecular Pain

Figure 5

From: Inhibition of tetrodotoxin-resistant sodium current in dorsal root ganglia neurons mediated by D1/D5 dopamine receptors

Figure 5

Effect of SKF 81297 on the steady-state activation and inactivation curves of TTX-R sodium channels. A) Voltage-dependence activation of TTX-R sodium channels. TTX-R voltage-gated sodium currents were elicited by 500 msec steps from a holding potential of – 80 mV to voltages between −120 and + 30 mV in 10 mV increments. B) Voltage-dependence of inactivation of TTX-R sodium channels. TTX-R voltage-gated sodium currents were elicited with a test pulse to −10 mV preceded by 500 msec prepulses from −120 to + 30 mV in 10 mV increments. C) Collected results showing the effect of 10 μM SKF 81297 on the steady-state activation curve of TTX-R sodium channels in small DRG neurons (diameter ≤ 25 μm). The steady-state activation curve had a midpoint for activation of −15.1 ± 4.2 mV and a slope of 5.0 ± 1.8 mV (n = 17) in control (circles) versus −12.7 ± 7.4 mV (t-test, two populations, p = 0.270) and 4.9 ± 2.1 mV (n = 15) in neurons incubated for 15 min in 10 μM SKF 81297 (diamonds). Dotted lines are best fits to the Boltzmann function. Error bars were omitted for clarity. D) Collected results showing the effect of 10 μM SKF 81297 on the steady-state inactivation curve of TTX-R sodium channels (same neurons as in C). The steady-state inactivation curve had a midpoint for inactivation of −34.7 ± 3.2 mV and a slope of 4.9 ± 1.1 mV (n = 17) in control (circles) versus −31.3 ± 4.2 mV (t-test, two populations, *p < 0.05) and 5.2 ± 1.9 mV (n = 15) in 10 μM SKF 81297 (diamonds). Dotted lines are best fits to the Boltzmann function. Error bars were omitted for clarity.

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