Figure 2. Bar graphs of the character of the bladder responses evoked by PN stimulation at 10 Hz (white bar), 33 Hz (black bar), and 100 Hz (grey bar) as a function of stimulus train duration.

A, the percentage of trials where stimulation generated sustained bladder contractions depended on the stimulation frequency, stimulus train duration, and the interaction between frequency and duration. B, the percentage of trials in which PN stimulation inhibited the bladder depended on stimulation frequency and the interaction between stimulus frequency and train duration, but not on train duration alone. C, the percentage of trials where PN stimulation evoked neither a sustained bladder contraction nor sustained inhibition of the bladder was dependent on stimulus duration, but on neither stimulus frequency nor the interaction between stimulus frequency and train duration. D, bladder inhibition in those trials where PN stimulation was delivered during elevated bladder pressure. The numbers above the bars are the number of trials across cats. *Stimulus parameters evoking a significantly greater percentage of sustained bladder contractions (P < 0.05, non-parametric comparison based on Bonferroni inequalities (Gibbons, 1993). All stimulation amplitudes were between 2 × and 4 × PN_thr and all bladder volumes were above threshold for distension-evoked contractions.