Fig. 1

Electrophysiological and pharmacological properties of the caps⁻lpH⁺ small-sized DRG neurons studied for diabetes-induced changes in T-type current. a A representative trace showing absence of capsaicin-induced current in the caps⁻lpH⁺ neurons. b A representative trace demonstrating substantial low-pH-induced current in the caps⁻lpH⁺ neurons. c Representative traces of Ba²⁺ currents demonstrating expression of T-type channels in the caps⁻lpH⁺ neurons. The currents were evoked by voltage depolarizing steps from a holding potential of −100 mV to −80 through −10 mV in 10 mV increments. d Representative traces of total currents recorded in the caps⁻lpH⁺ neurons that included Na⁺, Ca²⁺ and K⁺ components. The currents were evoked by voltage steps from a holding potential of −100 to −60 through 40 mV in 20 mV increments. e At the top, a representative trace of AP evoked by a threshold 1 millisecond-long current pulse shown at the bottom. APb is an action potential duration at the base. AHP80 is the time required for the AHP to decay to 80 % of its peak value. f An example demonstrating that the caps⁻lpH⁺ neurons are IB4-negative. A fluorescent image of DRG neurons stained for IB4 is shown in the left rectangle. Two IB4-positive small DRG neurons are clearly visible in the top right corner of the image. White box in a bottom left corner of the image indicates an area where IB4-negative caps⁻lpH⁺ neuron is located. Fluorescent and transmitted light images of the boxed caps⁻lpH⁺ neuron are presented in the top and bottom right squares, respectively. The IB4-negative caps⁻lpH⁺ neuron is outlined with a white dashed circle on fluorescent images and a black dashed circle on transmitted light image. No IB4 fluorescence is visible on the plasma membrane of this caps⁻lpH⁺ neuron. A scale bar is 15 μm. This neuron had a K⁺ “current signature” specific for the caps⁻lpH⁺ DRG neurons