Effects of some different pulse parameters on bladder inhibition and urethral closure during intravaginal electrical stimulation: an experimental study in the cat.

Intravaginal electrical stimulation (IVS) was used in the cat to induce bladder inhibition and urethral closure. The purpose of the study was to compare the efficacy of alternating constant-voltage pulses of different durations (0·1, 0·2, 0·5 and 5 ms) with that of chopped alternating pulses, each consisting of a train of five 0·5 ms pulses with 0·5 ms pauses between. The voltage requirement for an equal biological effect was lowest for the 5 ms alternating pulse, whereas the pulse power dissipation was lowest for the 0·1 ms pulse, about 10 per cent of that for the 5 ms pulse. If both voltage requirement and power dissipation are taken into account, the 0·5 ms pulse was considered the most appropriate compromise. The chopped pulse was the least efficient stimulus, since the threshold voltage was comparable to that of the 0·5 ms duration alternating pulse, implying a five times higher power dissipation. For bladder inhibition, the optimal stimulation frequency for alternating pulses was 10 Hz, both in terms of threshold voltage and power consumption. For urethral closure the voltage requirement was lowest at 50 Hz but 20 Hz was preferable in terms of power dissipation for an equal, although submaximal, effect.