Figure 5

Acute neck muscle inflammation alters subthreshold voltage-activated currents. A. Traces show representative voltage-activated current recordings (from control, sham, and carrageenan-injected animals) in response to voltage step protocol (bottom black traces, note different scale for lower right I_h currents). We have previously shown this protocol identifies one of four dominant currents in dorsal horn neurons: rapid A-type potassium currents (I_{A rapid}); slow A-type potassium currents (I_{A slow}); T-type calcium currents (I_Ca); and a hyperpolarisation-activated non-selective cation current (I_h). Analysis of these currents across the three experimental conditions showed the characteristics of I_{A slow}, I_Ca, or I_h did not differ under the three conditions. In contrast, the amplitude of the I_{A rapid} current was reduced in carrageenan-injected animals (see text). B. Plots show the incidence of sub-threshold voltage activated current types was similar in control, sham, and carrageenan-injected animals.