Effects and mechanisms of vaginal electrical stimulation on gastric tone in dogs

Electrical stimulation of one part of the gut may have beneficial or adverse effects on another region. We hypothesized that electrical stimulation of a visceral organ in one system might have an effect on another visceral organ system. That is, disorders of one system may be treated by interventions of another system and this may lead to a more convenient or less invasive therapies in some cases. The aim of this study was to evaluate the effects and mechanisms of vaginal electrical stimulation (VES) with different parameters on gastric tone and gastric slow waves in conscious dogs. Seven dogs were studied in two experiments. Experiment 1 was to study effects of VES on gastric tone and slow waves. Experiment 2 was performed in two sessions (long pulse VES plus guanethidine and VES with trains of long pulse plus guanethidine) to study involvements of possible sympathetic mechanisms. The results of our experiments were: (i) VES increased the gastric volume in a dose-dependent manner with the increase of stimulation frequency, amplitude or pulse width; (ii) VES had no effects on gastric slow waves; (iii) the inhibitory effect of VES with long pulses or trains of long pulses on gastric tone was abolished by guanethidine; and (iv) few or mild symptoms were noted with stimulation. VES decreases proximal gastric tone in an energy-dependent manner without affecting gastric slow waves. The inhibitory effect of VES is mediated by a sympathetic pathway. Hypertensive gastric tone might be treated using electrical stimulation of the vagina which is minimally invasive.