Gastric electrical stimulation with short pulses reduces vomiting but not dysrhythmias in dogs

Abstract

Background & Aims: The aim of this study was to investigate the acute effects of 3 different methods of electrical stimulation in the prevention of vasopressin-induced emetic response and gastric dysrhythmias. Methods: Seven female hound dogs chronically implanted with 4 pairs of electrodes on gastric serosa were used in a 5-session study. Saline and vasopressin were infused in sessions 1 and 2, respectively. In the other 3 sessions with vasopressin infusion, 3 different methods of electrical stimulation (short-pulse stimulation, longpulse stimulation, and electroacupuncture) were applied. Gastric slow waves and vomiting and behaviors suggestive of nausea were recorded in each session. In a separate study, additional experiments were performed in 5 vagotomized dogs to investigate vagally mediated mechanisms. Results: Vasopressin induced gastric dysrhythmias, uncoupling of slow waves, and vomiting and behaviors suggestive of nausea (P < 0.02, analysis of variance). Long-pulse stimulation, but not short-pulse stimulation or electroacupuncture, was capable of preventing vasopressin-induced gastric dysrhythmias and gastric slow wave uncoupling. Shortpulse stimulation and electroacupuncture, but not longpulse stimulation, prevented vomiting and significantly reduced the symptom scores, which was not noted in the dogs with truncal vagotomy. Conclusions: Long-pulse stimulation normalizes vasopressin-induced slow wave abnormalities with no improvement in vomiting and behaviors suggestive of nausea. Short-pulse stimulation and electroacupuncture prevent vomiting and behaviors suggestive of nausea induced by vasopressin but have no effects on slow waves, and their effects are vagally mediated.