Fig. 7.
Effect of capsaicin on neuromodulation of the micturition reflex. A and B: typical experimental records showing effects of spinal nerve stimulation by high current intensity (0.6 mA, ∼6 * Tmot, 0.5 Hz; A) and threshold current intensity (Tmot, 10 Hz, pulse width 0.1 ms; B) on bladder reflex contraction (mmHg) in rats with capsaicin (125 mg/kg sc) pretreatment 4 days before the bladder reflex contraction study. The black bars indicate 10-min duration of spinal nerve stimulation. C and D: time course for the effect of spinal nerve stimulation at high intensity (0.6 mA, ∼6 * Tmot, 0.5 Hz; C) and threshold intensity (10 Hz; D) on frequency of bladder reflex contraction in rats with vehicle and capsaicin (125 mg/kg sc) pretreatment 4 days before the bladder reflex contraction study. The responses are represented as a percentage of control (%control), where the baseline response before stimulation is defined as 100%. Significant differences between the tests and control values were demonstrated by ANOVA followed by Bonferroni posttest. Shaded areas are responses during electrical stimulation. *P < 0.05 Bonferroni posttest. In capsaicin-pretreated rats, high intensity of current stimulation produced a stronger inhibition of frequency of bladder contractions (P < 0.05 vs. vehicle treated, 2-way ANOVA); Tmot intensity stimulation produced a trend of stronger inhibitory effects but was not statistically significant (P = 0.03 vs. vehicle-treated, 2-way ANOVA).