Effects of gastric electrical field stimulation with long pulses on gastric emptying in dogs

Abstract

The aim was to investigate the effects of electrical field stimulation (EFS) with long and short pulses on gastric emptying, gastric contractility and vagal activity in dogs. Sixteen dogs were equipped with a duodenal cannula, electrodes and strain gauges (10 dogs) in the stomach. Each dog was fed with Ensure and gastric effluent was collected from the cannula. Electrical stimulation was applied via two electrodes (about 12 cm apart, one in the corpus and the other in the antrum) with long pulses (a frequency of 6 cycles min-1, pulse amplitude of 6 mA and width of 100 ms) in 10 dogs and with short pulses (frequency of 30 Hz and pulse width of 300 micros) in six dogs. The electrocardiogram was also recorded and heart rate variability was derived to assess the vagal activity. It was found that: (i). EFS with long pulses did not alter gastric emptying during stimulation but increased gastric emptying during the 45 min immediately after stimulation; (ii). EFS with long pulses increased gastric contractility in both proximal and distal antrum during and after the stimulation; (iii). EFS with long pulses resulted in an increase in vagal tone during the 45 min immediately after stimulation. However, there is no difference during the 45 min period of stimulation; (iv). EFS with short pulses had no effect on gastric emptying. We concluded that long pulse gastric electrical field stimulation with one electrode in the corpus and the other electrode in the antrum has postponed effects on gastric emptying of liquid, gastric contractility and vagal activity.

Modulatory effects and afferent pathways of gastric electrical stimulation on rat thoracic spinal neurons receiving input from the stomach

“…Long-pulse stimulation is capable of preventing dysrhythmias and uncoupling the gastric slow waves, whereas the shortpulse stimulation and electroacupuncture significantly reduces vomiting, a symptom of nausea, via the vagal-mediated pathway in dogs and rats Liu et al 2004). Long-pulse field electrical stimulation has delayed effects on gastric emptying of liquid, gastric contractility and vagal activity (Ouyang et al 2003). In the present study, we used four sets of stimulation parameters and the selection of these parameters was based on the following: Parameter A is the set of parameters commonly used for the treatment of obesity (D'Argent et al 2002); in parameter B, the frequency is reduced to 14 Hz which is commonly used in treating nausea and vomiting in patients with gastroparesis (Abell et al and Forster et al 2002); Parameter C is similar to Parameter A except that the pulse width is increased to 3ms.…”

“…For example, vagotomy eliminates the anti-emetic effects of short-pulse GES on nausea and vomiting induced by vasopressin . Using an advanced spectral analysis of heart rate variability for the assessment of vagal activity, GES is found to be involved with increased vagal activity and accelerated gastric emptying in dogs and rats (Liu et al 2004;Ouyang et al 2003). Additionally, GES is reported to produce an increase in the firing rate of vagal single afferent fibers associated with antral contractions of the stomach in rats (Peles et al 2003), and GES mainly exerts excitatory effects on NTS neuronal activity (Qin et al 2005).…”

“…The stomach receives dual innervations by vagal and splanchnic (sympathetic) nerves in both humans and animals, which play an important role in the regulation of gastric function. Previous studies using atropine and vagotomy in dogs have indicated that vagal afferent and/or efferent pathways are involved in the regulation of GES on gastric motility Grundfest-Bronaltowski et al 1990;Liu et al 2004;Ouyang et al 2003). In rats, GES can activate vagal afferent fibers innervating the stomach (Peles et al 2003) and modulate neuronal activity in the nucleus tractus solitarii, where vagal afferent fibers terminate (Qin et al 2005).…”

Characterization of T9–T10 spinal neurons with duodenal input and modulation by gastric electrical stimulation in rats

“…Vagotomy eliminates the anti-emetic effects of short-pulse GES on nausea and vomiting induced by vasopressin . The assessment of vagal activity with an advanced spectral analysis of heart rate variability indicates that effects of GES with certain parameters are relevant to increased vagal activity and accelerated gastric emptying in dogs and rats (Liu et al 2004;Ouyang et al 2003). Furthermore, intravenous administration of an adrenergic blocker prevents the inhibitory effect of GES on antral motility and/or rectal tone, indicating an involvement of the sympathetic adrenergic nerve fibers (Zhu and Chen 2005;Liu et al 2005;Ouyang et al 2005).…”

“…Both the duodenum and the stomach receive dual innervations by vagal (parasympathetic) and splanchnic (sympathetic) nerves in humans and animals, which play an important role in the regulation of gastric function. Effects of GES on gastric motility have been shown to involve vagal afferent and/or efferent pathways in dogs Grundfest-Bronaltowski et al 1990;Liu et al 2004;Ouyang et al 2003). In rats, GES can activate vagal afferent fibers innervating the stomach (Peles et al 2003) and modulate activity of neurons in the nucleus tractus solitarii receiving gastric vagal afferents (Qin et al 2005).…”