Figure 13.

The presence or absence of DMSO has no effect on the actions of synthetic 3-carboxy-1-methyl pyridinium (CMP) on DRG neurones. A) Records of action potentials showing single action potential firing under control conditions and multiple firing induced by CMP (100 μM) in the presence of 0.1% DMSO. B) Records of action potentials showing single action potential firing under control conditions and multiple firing induced by CMP (100 μM) in the absence of DMSO. At rest both neurones were held at -70 mV C) Bar chart showing the significant decrease in the mean voltage-activated K⁺ current (holding potential -70 mV, clamp potential for current activation +60 mV) evoked by CMP (100 μM) in the presence of 0.1% DMSO. D) Bar chart showing the significant decrease in the mean voltage-activated K⁺ current (holding potential -70 mV, clamp potential for current activation +60 mV) evoked by CMP (100 μM) in the absence of DMSO. E & F) Current traces under voltage clamp showing the decrease in K⁺ current produced by CMP.