Figure 1

Membrane and action potential properties of TTXs/TRPM8 and TTXr/TRPM8 DRG neurons. A) A menthol-sensitive DRG neuron (arrow indicated) identified by the Ca²⁺-imaging method (left and middle panels). Under current-clamp configuration, a menthol-sensitive cell responded to cold stimulation with membrane depolarization and action potential firing (Right panel). Membrane response was shown in the upper trace and temperature drop in the lower trace. B-C) Action potential firing in response to current injection through patch-clamp electrode in two menthol/cold-sensitive cells. One cell had lower threshold for action potential firing and narrow action potentials (B), and the other showed higher threshold and broader action potentials (C). D-E) Effects of TTX (500 nM) on action potential firing in menthol/cold-sensitive cells. For the cell type represented in B, action potential firing was sensitive to TTX and abolished in the presence of 500 nM TTX (TTXs/TRPM8 cell, D). For the cell type represented in C, action potential firing is resistant to TTX block (TTXr/TRPM8 cell, E). Except the right trace in A, all experiments were performed at 24°C. Membrane parameters and statistical comparison are summarized in Table 1.