Fig. 6
Contribution of TTX-R INaP to the excitability of dural afferent neurons. A. Typical voltage traces in response to depolarizing current injections in the absence (left) and presence (right) of 300 nM TTX in small- (a) and medium-sized (b) DiI-positive neurons. Three representative raw traces were elicited by one-fold threshold (1 T; 150 and 80 pA in small- and medium-sized neurons, respectively) to three-fold threshold depolarizing current injections. Phasic and tonic firing patterns are shown for small- and medium-sized DiI-positive neurons, respectively. B. Changes in the number of action potentials elicited by depolarizing current injections (1 T to 4 T) in the absence (open circles) and presence (closed circles) of 300-nM TTX in small- (a) and medium-sized (b) DiI-positive neurons. The points and error bars represent the mean and SEM from 25 small- and 31 medium-sized DiI-positive neurons. **; p < 0.01, n.s; not significant (paired t-test). C. a, Typical voltage traces in response to depolarizing current injections recorded before (upper), during (middle), and after (lower) the application of 10 μM riluzole. Four representative raw traces were elicited by one-fold threshold (1 T; 100 pA) to four-fold threshold (4 T; 400 pA) depolarizing current injections in medium-sized DiI-positive neurons. b, Typical voltage traces in response to hyperpolarizing current injections recorded before (upper), during (middle), and after (lower) the application of 10 μM riluzole in the same neuron shown in Ca. Notably, 50 μM ZD7288 but not 10 μM riluzole greatly attenuated sag potentials (arrows). D. Changes in the number of action potentials elicited by depolarizing current injections (1 T to 4 T) in the absence (open circles) and presence of riluzole (1, 3, and 10 μM) in small- (a) and medium-sized (b) DiI-positive neurons. The points and error bars represent the mean and SEM from six small- and six medium-sized DiI-positive neurons. E. Typical action potentials elicited by brief depolarizing current injections (3 ms duration, 300 pA) in the absence (black) and presence (gray) of 10 μM riluzole in medium-sized DiI-positive neurons. Note that riluzole (10 μM) did not affect the afterhyperpolarization (AHP) of action potentials. F. Riluzole (10 μM)-induced changes in the amplitude of AHP (a) and decay time constant of AHP (b) in medium-sized DiI-positive neurons. The columns and error bars represent the mean and SEM from six medium-sized DiI-positive neurons. n.s; not significant (paired t-test)