CHEMOSENSITIVITY OF C-CELLS IN BULLFROG DORSAL-ROOT GANGLIA TO SUBSTANCE-P AND ADENOSINE 5'-TRIPHOSPHATE

Dissociated bullfrog dorsal root ganglion cells were voltage clamped i n the whole-cell configuration. In small C-cells having 20 mu m as ave raged diameter, substance-P (0.1-1 mu M) inhibited an M-type potassium current while ATP (1-10 mu M) activated a sodium-potassium current. I n large A-cells (approximate to 65 mu m in diameter) in which ATP has been shown to inhibit M-current, substance P (0.1-1 mu M) also inhibit ed this potassium current without activating the sodium-potassium curr ent. Results provided evidence for the distinction between A- and C-ce lls in terms of their chemosensitivity.