The Effect on Gastric Tone of Gastric Electrical Stimulation with Trains of Short Pulses Varies with Sites and Stimulation Conditions

BACKGROUND: Gastric electrical stimulation (GES) can improve symptoms in patients with gastroparesis and induce weight loss in obese subjects. AIMS: To evaluate the effect on gastric tone of GES under different conditions at different sites of the stomach. METHODS: Eleven dogs were implanted with a gastric cannula and two pairs of stimulation electrodes (in the middle of the lesser curvature and of the greater curvature, 10 cm from the pylorus). Gastric tone was assessed with a barostat. GES was applied using: (1) Enterra conditions (14 Hz, 5 mA, 0.3 ms, 0.1 s on, 5 s off); (2) modified Enterra conditions (40 Hz, 5 mA, 0.3 ms, 0.1 s on, 5 s off); and (3) implantable gastric stimulation (IGS) conditions (40 Hz, 5 mA, 0.3 ms, 2 s on, 3 s off). Six sessions were performed randomly with each animal on six separate days. RESULTS: (1) At the lesser curvature, GES with modified Enterra conditions significantly elevated gastric volume from 96.9 +/- 8.3 ml at baseline to 133.9 +/- 11.7 ml (P = 0.015) and a similar effect was observed with IGS (91.3 +/- 7.1 ml vs. 186.3 +/- 27.1 ml, P = 0.013). GES with Enterra conditions had no such an effect. (2) At the greater curvature, GES with Enterra conditions significantly increased gastric volume from basal 94.1 +/- 4.4 ml to 122.1 +/- 11.3 ml (P = 0.032); modified Enterra conditions had the opposite effect (96.5 +/- 9.0 ml vs. 77.4 +/- 11.7 ml, P = 0.025) and no significant effect was observed with IGS conditions. CONCLUSION: The effects of GES on gastric tone vary with the conditions and sites of stimulation. These findings may help to explain the distinct effects of GES therapy in patients with gastroparesis and obesity.     

Gastric Electrical Stimulation Does Not Significantly Affect Canine Gastric Acid Secretion and 24-Hour Gastric pH

Gastric electrical stimulation (GES) was shown to improve symptoms in patients with gastroparesis. However, the underlying mechanisms remain unclear. This study assessed the influence of various patterns of GES on fasting and postprandial gastric acid secretion and 24-hr gastric pH. Eight healthy dogs were studied and we found that in the fasting state, low-frequency, long-pulse (6/12-cpm, 375-msec, 4-mA) GES at the proximal stomach significantly inhibited the secretion of gastric juice (P < 0.05). No such effect was observed during GES (6/12 cpm) at the distal stomach. In the postprandial period, low-frequency, long-pulse GES at both proximal and distal sites and at both frequencies did not significantly affect gastric acid secretion. High-frequency, short-pulse GES, investigated for obesity (21 Hz, 8 mA, and 250 microsec, with 2 secs on, 3 sec off), at the proximal and distal stomach did not significantly affect the 24-hr gastric pH profile. In conclusion, GES with various stimulation parameters, and at various sites, has little effect on gastric acid secretion. The clinical effects induced by GES at these parameters may not be related to their effect on gastric acid homeostasis.     

Gastric electrical stimulation using endoscopically placed mucosal electrodes reduces food intake in humans

BACKGROUND: Implantable gastric stimulation (IGS) has been proposed for treating obesity. The aim of this study was to investigate the effects of temporary mucosal electrical stimulation on water and food intake as well as gastric emptying in healthy humans. METHODS: The study was designed to study the effects of temporary gastric electrical stimulation (GES) on symptoms, gastric accommodation, food intake, and gastric emptying. It was performed in 12 healthy volunteers on 3 consecutive days. GES was performed using mucosal electrodes endoscopically placed in the fundus. RESULTS: The amount of maximum water intake was reduced with GES (894 +/- 326 mL) compared with sham-GES (1,093 +/- 417 mL, p = 0.01). The food intake was also reduced with GES (p = 0.012). In comparison with sham stimulation, GES delayed gastric emptying during the first 45 min after the meal but not during the remaining time. GES with parameters effective in reducing water and food intake and delaying gastric emptying did not induce significant dyspeptic symptoms, compared with sham stimulation. CONCLUSIONS: GES using temporary mucosal electrodes decreases food intake as well as maximum intake of water, and has a tendency of delaying gastric emptying. It may have a potential application for the treatment of obesity.     

Electroacupuncture Restores Impaired Gastric Accommodation in Vagotomized Dogs

The aim of this study was to investigate the effects of electroacupuncture (EA) on impaired gastric accommodation in a canine model. Ten dogs were chronically implanted with a gastric cannula in the stomach. Truncal vagotomy was performed in five of the dogs. A polyethylene bag attached at the end of a catheter was placed in the proximal stomach via the cannula. Gastric compliance, gastric tone, and postprandial gastric accommodation were evaluated using a gastric barostat with and without EA on two separate days, respectively. Results were as follows. (1) The postprandial gastric volume increase was 180.8 +/- 54.3 ml in vagotomized dogs, which was significantly lower than that (317.3 +/- 37.3 ml; P < 0.05) in normal dogs. (2) In normal dogs, EA did not affect gastric compliance, basal gastric tone, or postprandial gastric accommodation. (3) In vagotomized dogs, EA did not affect gastric compliance or basal gastric tone but restored the impaired gastric accommodation. The postprandial gastric volume increase was significantly enhanced with EA compared to the control (275.0 +/- 45.8 vs. 180.8 +/- 54.3 ml; P < 0.02). EA restores impaired gastric accommodation induced by vagotomy and may have therapeutic potential for patients with gastroparesis.     

Gastric electrical stimulation reduces gastric tone energy dependently

OBJECTIVE: Impaired gastric accommodation is one of the major pathophysiological factors in functional dyspepsia (FD). Gastrointestinal electric stimulation (GES) as a potential therapy for treating patients with motility disorders has been applied in animal models and clinical practice. However, the response of proximal gastric tone to different GES has not been fully understood. Therefore, the aims of this study were to investigate the effects of GES with different parameters on gastric tone and to estimate the relationship between gastric volume, stimulation energy, and symptoms. MATERIAL AND METHODS: Seven dogs equipped with a gastric cannula and two pairs of serosal electrodes in the greater curvature were studied with different GES via a pair of electrodes located 10-14 cm above the pylorus. The gastric volume under constant pressure was measured using a barostat device. RESULTS: The results showed that 1) GES increased the gastric volume in a dose-dependent manner with the increase of stimulation frequency or pulse amplitude. 2) The increase in gastric volume with GES was significantly correlated to stimulation energy. 3) Mild symptoms were noted with stimulation and the score of the induced symptoms was linearly and significantly correlated with gastric volume. CONCLUSIONS: GES decreases the proximal gastric tone in an energy-dependent manner. These data suggest that GES could be used to treat patients with impaired gastric accommodation.     

Gastric electrical stimulation for gastroparesis: a goal greatly pursued, but not yet attained

The lack of an effective medical treatment for gastroparesis has pushed the research of new techniques of gastric electrical stimulation (GES) for nearly half a century of experimentation with a large variety of electrical stimuli delivered to the gastric wall of animals and patients with gastroparesis. Three principal methods are currently available: gastric low-frequency/high-energy GES with long pulse stimulation, high-frequency/low-energy GES with short pulse stimulation and neural sequential GES. The f...     

Treatment of gastroparesis with electrical stimulation

Electrically stimulating the stomach to treat gastroparesis has been proposed by investigators for decades. With the development of techniques of implantable pacing devices and electrodes and promising preliminary results in chronic pacing studies, gastric electrical stimulation (GES) has received increasing attention recently among researchers and clinicians. A number of studies have been performed to investigate the effects of GES on gastric motility, gastric emptying, and gastrointestinal symptoms in both dogs and humans. Based on the frequency of the electrical stimulus used for chronic treatment of gastroparesis, gastric electrical stimulation can be classified into low-frequency stimulation (LFS) and high-frequency stimulation (HFS). Although some of the results are still controversial, the majority of these studies seem to indicate that LFS is able to normalize gastric dysrhythmias and entrain gastric slow waves and accelerate gastric emptying. On the other hand, HFS has no effect on gastric emptying but is able to significantly reduce symptoms of nausea and vomiting in gastroparetic patients. GES has provided an exciting new advance in the treatment of gastroparesis and management of upper gastrointestinal symptoms. This paper will review the available studies of GES in the treatment of gastroparesis and current status of this field.     

Gastric electrical stimulation: An emerging therapy for children with intractable gastroparesis

Management of gastroparesis remains challenging, particularly in pediatric patients. Supportive care and pharmacological therapies for symptoms remain the mainstay treatment. Although they are effective for mild and some moderately severe cases, often time they do not work for severe gastroparesis. There are a few prokinetics available, yet the use of these drugs is limited by a lack of persistent efficacy and/or safety concerns. Currently, the only modality for adult patients with severe intractable gastroparesis is surgery, e.g., pyloroplasty and partial gastrectomy, however, this option is generally considered too radical for a growing child. Novel therapeutic approaches, particularly those which are less invasive, are needed. This article explores gastric electrical stimulation (GES), a new therapy for gastroparesis. Unlike others, it neither needs medications nor gastrectomy; rather, it treats through the use of microelectrodes to deliver high-frequency low energy electric stimulation to the pacemaker area of the stomach. Thus, it is tolerated and safe in children. Like in adult patients, GES appears to work in releasing symptoms, improving nutrition, and enhancing the quality of life; it also helps wean off medications and eliminate many needs for hospitalization. Considering the transient nature of gastroparesis in children in many occasions, GES is considered a “bridging” therapy after failed medical interventions and before surgery.     

The origin of symptoms on the brain-gut axis in functional dyspepsia

It was hypothesized that symptoms in functional dyspepsia are originated by an altered mechanism at the brain-gut axis (one or several) in the process of gastric accommodation to a meal. To test the key mechanisms potentially involved in symptomatic gastric accommodation, the sensorial responses (on a 0-10 perception score) and the gastric tone responses (by electronic barostat) to either gastric accommodation (n = 10) or to cold stress (n = 10) were measured in 20 patients with functional dyspepsia and 20 healthy controls. The mechanical accommodation of the stomach to gastric distention (compliance) was similar in patients (52 +/- 8 mL/mm Hg) and controls (57 +/- 6 mL/mm Hg). However, isobaric gastric distention elicited more upper abdominal discomfort in dyspeptics than in controls (perception scores, 4.7 +/- 0.9 vs. 1.1 +/- 0.5, respectively; mean +/- SE; P less than 0.005). Cold stress induced a similar gastric relaxatory response in dyspeptics and controls (delta vol, 145 mL +/- 40 mL vs. 141 mL +/- 42 mL, respectively); hand perception (scores, 8.3 +/- 0.4 vs. 7.9 +/- 0.4, respectively) and autonomic responses were also similar. It is concluded that an abnormal afferent sensorial pathway (altered gastric perception) may be a major mechanism of symptom production in functional dyspepsia.     

Gastric electrical stimulation in patients with gastroparesis

Abstract As in the heart, there is a pacemaker in the human stomach and it generates myoelectrical activity with a frequency of approximately three cycles per minute. Abnormalities in gastric myoelectrical activity may result in gastric motility disorders, such as gastroparesis. Electrical stimulation of the stomach is achieved by delivering electrical currents via electrodes attached to the smooth muscle of the stomach. Recently, a number of studies on electrical stimulation of the stomach in both humans and dogs have indicated that gastric electrical stimulation with appropriate parameters is able to entrain gastric slow waves and normalize gastric dysrhythmias. This has led some investigators to use gastric electrical stimulation to treat patients with gastroparesis. Previous studies and the current state of the field in gastric electrical stimulation in treatment of gastroparesis will be discussed and summarized.     

Long-pulse gastric electrical stimulation at tachygastrial frequency reduces food intake by inhibiting proximal gastric tone

OBJECTIVE: To investigate the effects of long pulse gastric electrical stimulation (GES) at a tachygastrial frequency on food intake, gastric tone and gastric myoelectrical activity (GMA). MATERIAL AND METHODS: Of twelve dogs implanted with electrodes and a gastric cannula, 6 underwent truncal vagotomy. Stimulus consisted of long pulses with a frequency of 9 cycles/min. Experiment one was performed in all dogs to test for food intake with or without GES. Experiment two on six normal dogs consisted of baseline, GES and recovery periods. Gastric volume and GMA were recorded. RESULTS: 1) GES reduced food intake in both normal (398.5+/-111.7 g versus 573.0+/-97.9 g; p<0.02) and vagotomized dogs (170.6+/-100.4 g versus 401.0+/-97.3 g; p<0.05). 2) Gastric volume was increased with stimulation from 168.4+/-17.7 ml to 301.1+/-34.1 ml (p<0.02 ANOVA) and maintained at 271.8+/-27.6 ml. 3) The percentages of normal slow waves before, during and after GES were 83.3+/-4.6%, 38.0+/-3.5% and 61.0+/-12.5%, respectively (p=0.02 ANOVA). CONCLUSION: Long-pulse GES at tachygastrial frequency substantially reduces food intake, and is not mediated by the vagal pathway but attributed to relaxation of the stomach and impairment of intrinsic GMA.     

Clinical response to gastric electrical stimulation in patients with postsurgical gastroparesis.

BACKGROUND & AIMS: The aim of this study was to report the long-term clinical response to high-frequency gastric electrical stimulation (GES) in 16 patients with postsurgical gastroparesis who failed standard medical therapy. METHODS: Clinical data collected at baseline and after 6 and 12 months of GES included (1) severity and frequency of 6 upper gastrointestinal (GI) symptoms by using a 5-point symptom interview questionnaire and total symptom score, (2) health-related quality of life including physical composite score and mental composite score, (3) 4-hour standardized gastric emptying of a solid meal by scintigraphy, and (4) nutritional status. RESULTS: The severity and frequency of all 6 upper GI symptoms, total symptom score, physical composite score, and mental composite score were significantly improved after 6 months and sustained at 12 months ( P < .05). All patients had delayed gastric emptying at baseline. Gastric emptying was not significantly faster at 12 months, although 3 normalized. At implantation, 7 of 16 patients required nutritional support with a feeding jejunostomy tube; after GES, 4 were able to discontinue jejunal feeding. The mean number of hospitalization days was significantly reduced by a mean 25 days compared with the prior year. One patient had the device removed after 12 months because of infection around the pulse generator. CONCLUSIONS: Long-term GES significantly improved upper GI symptoms, quality of life, the nutritional status, and hospitalization requirements of patients with postsurgical gastroparesis. Although vagal nerve damage or disruption was part of the underlying pathophysiology, GES therapy was still effective and is a potential treatment option for the long-term management of postsurgical gastroparesis. A controlled clinical trial of GES for PSG patients (who are refractory to medical therapy) is indicated given these encouraging results.     

Feasibility of gastric electrical stimulation by use of endoscopically placed electrodes

BACKGROUND: Gastric electrical stimulation (GES), which has been reported to have therapeutic potentials for gastroparesis and obesity, involves the surgical placement of electrodes with the patient under general anesthesia. New methods are needed for implanting GES electrodes in a safer and more feasible way. OBJECTIVE: Our purpose was to investigate the safety and feasibility of placing electrodes endoscopically for GES. DESIGN AND SETTING: A pilot study. SUBJECTS: Six female hound dogs that weighed 13 to 22 kg. INTERVENTIONS: Endoscopically placed electrodes passed through the abdomen and the stomach wall. MAIN OUTCOME MEASUREMENTS: The study was performed in dogs surgically implanted with gastric serosal electrodes and endoscopically implanted electrodes. The experiment consisted of a 30-minute baseline, a 30-minute GES, and a 30-minute recovery. GES was performed through endoscopically placed electrodes. Gastric slow waves were simultaneously recorded with the serosal electrodes and the endoscopically placed electrodes. RESULTS: (1) The slow wave frequency recorded from the endoscopically placed electrodes was significantly correlated with that from the serosal electrodes (r = 0.97, P < .002). (2) GES through the endoscopically placed electrodes was able to entrain gastric slow waves. (3) No gastric leakage into the abdominal cavity was noted and the dogs were healthy and comfortable. (4) The endoscopically placed electrodes remained for 2 to 3 weeks. LIMITATIONS: The fixation of the electrodes needs to be improved for longer-term uses. CONCLUSIONS: GES may be accomplished without surgery by inserting the electrode wire through the abdomen under endoscopy. The study results indicate that the endoscopically placed electrodes are effective for GES and do not result in any adverse events.     

Effect of Acute Gastric Electrical Stimulation on the Systemic Release of Hormones and Plasma Glucose in Dogs

This study evaluated the effect of gastric electrical stimulation (GES) with various parameters on plasma concentrations of satiety-related peptides and glucose. GES was performed in nine healthy dogs via electrodes implanted in the middle of the lesser curvature. Four sessions were performed in each animal: control, stimulation with IGS (implantable gastric stimulation for obesity, 0.3 m sec), modified IGS (2 msec), and long pulses (300 msec). Blood samples were collected at 15 and 0 min before the meal and at 15, 30, and 60 min after the meal. GES was initiated 30 min before the first blood sample and maintained throughout collection. Plasma ghrelin, leptin, insulin and glucose were measured. The total AUCs of plasma ghrelin and leptin were not significantly affected by GES. The total AUC of plasma insulin was significantly lower with IGS and long pulse parameters (P < 0.05). The total AUC for plasma glucose was significantly lower in sessions with long pulses and modified IGS parameters (P < 0.05). We conclude that acute GES is able to change the release of some satiety-related peptides. Whether this is associated with the changed eating behavior and weight loss in obese patients needs further investigation.     

Effect of two-channel gastric electrical stimulation with trains of pulses on gastric motility

AIM： To investigate the effect of two-channel gastric electrical stimulation （GES） with trains of pulses on gastric emptying and slow waves.METHODS： Seven dogs implanted with four pairs of electrodes and equipped with a duodenal cannula were involved in this study. Two experiments were performed.The first experiment included a series of sessions in the fasting state with trains of short or long pulses, each lasted 10 min. A 5-min recording without pacing was made between two sessions. The second experiment was performed in three sessions （control, single-channel GES, and two-channel GES）. The stimulus was applied via the 1st pair of electrodes for single-channel GES （GES via one pair of electrodes located at 14 cm above the pylorus）, and simultaneously via the 1st and 3rd channels for two-channel GES （GES via two pairs of electrodes located at 6 and 14 cm above the pylorus）, Gastric liquid emptying was collected every 15 min via the cannula for 90 min.RESULTS： GES with trains of pulses at a pulse width of 4 ms or higher was able to entrain gastric slow waves. Two-channel GES was about 50% more efficient than single-channel GES in entraining gastric slow waves. Two-channel but not single-channel GES with trains of pulses was capable of accelerating gastric emptying in healthy dogs. Compared with the control session, two-channel GES significantly increased gastric emptying of liquids at 15 rain （79.0% ± 6.4% vs 61.3% ± 6.1%, P 〈 0.01）, 30 min （83.2% ± 6.3 % vs 68.2% ± 6.9%, P 〈 0.01）, 60 min （86.9% ± 5.5 % vs 74.1% ± 5.9%, P 〈 0.01）, and 90 rain （91.0% ± 3.4% vs 76.5% ± 5.9%, P 〈 0.01）.CONCLUSION： Two-channel GES with trains of pulses accelerates gastric emptying in healthy dogs and may have a therapeutic potential for the treatment of gastric motility disorders.     

Treatment of high-frequency gastric electrical stimulation for gastroparesis

Background and Aims: The aim of this study was to assess the effects of gastric electrical stimulation (GES) on symptoms and gastric emptying in patients with gastroparesis, and the effects of GES on the three subgroups of gastroparesis. Methods: A literature search of clinical trials using high‐frequency GES to treat patients with gastroparesis from January 1995 to January 2011 was performed. Data on the total symptom severity score (TSS), nausea severity score, vomiting severity score, and gastric emptying were extracted and analyzed. The statistic effect index was weighted mean differences. Results: Ten studies (n = 601) were included in this study. In the comparison to baseline, there was significant improvement of symptoms and gastric emptying (P < 0.00001). It was noted that GES significantly improved both TSS (P < 0.00001) and gastric retention at 2 h (P = 0.003) and 4 h (P < 0.0001) in patients with diabetic gastroparesis (DG), while gastric retention at 2 h (P = 0.18) in idiopathic gastroparesis (IG) patients, and gastric retention at 4 h (P = 0.23) in postsurgical gastroparesis (PSG) patients, did not reach significance. Conclusions: Based on this meta‐analysis, the substantial and significant improvement of symptoms and gastric emptying, and the good safety we observed, indicate that high‐frequency GES is an effective and safe method for treating refractory gastroparesis. DG patients seem the most responsive to GES, both subjectively and objectively, while the IG and PSG subgroups are less responsive and need further research.     

Impaired drinking capacity in patients with functional dyspepsia: relationship with proximal stomach function.

BACKGROUND & AIMS: Impaired fundic accommodation to a meal and hypersensitivity to distention are increasingly recognized as important mechanisms underlying functional dyspepsia (FD). In the present study, we evaluated whether a drink test can predict such abnormalities and thus represent a noninvasive tool to study proximal stomach motor function. METHODS: Healthy volunteers (HV), nonconsulters with mild dyspeptic symptoms (MS), and patients with FD filled out a disease-specific questionnaire and underwent a drink test with either water or with a high calorie fluid. The maximal ingested volume and the subsequent symptoms were meticulously recorded. In addition, all subjects underwent a gastric barostat study assessing meal-induced relaxation and sensation to distention. RESULTS: Drinking capacity was not significantly related to any particular dyspeptic symptom. FD were able to consume less water (893 +/- 70 mL) and caloric liquid (767 +/- 50 mL) compared with HV (water, 1764 +/- 120 mL; caloric liquid, 1308 +/- 96 mL) or MS (water, 1645 +/- 120 mL; caloric liquid, 973 +/- 45 mL). Approximately half of the FD had an abnormal water or Nutridrink test compared with 9% of MS and 4% of HV. Furthermore, FD developed significantly more symptoms than MS or HV after both drink tests. The drinking capacity did not predict impaired fundic accommodation or visceral hypersensitivity. CONCLUSIONS: FD, but not MS, have an impaired drinking capacity to both water and a nutrient liquid. The drinking capacity is not related to a specific dyspeptic symptom and does not predict proximal stomach motor function.     

胃电刺激对顺铂诱导的犬呕吐症状的影响

目的 研究顺铂(cisplatin,DDP)对胃肌电活动的影响,并探讨胃电刺激(GES)对化疗药物引起的犬呕吐和消化不良症状的治疗效应.方法 7只比格犬的胃浆膜均被植入4对电极,每只犬均先后进行两阶段实验.(1)DDP阶段:给予DDP(1.5 mg/kg),自给药开始持续记录胃电活动及动物症状;(2)GES+DDP阶段:自DDP给药开始,经近端胃体部电极持续给予串脉冲GES,给药剂量、胃电活动及症状记录同DDP阶段.结果 (1)DDP能诱导犬恶心呕吐症状及胃电紊乱:DDP阶段动物均出现频繁呕吐,呕吐次数为(5.5±1.2)次,总症状评分为31.83±2.75.通过胃电记录发现,基线水平时正常胃慢波占(96.50±1.14)%,而呕吐期间正常胃慢波占(69.61±5.81)%(P=0.003),并且胃电过速和胃电过缓发生的百分比均明显高于基线水平(P=0.020和P=0.031).(2)GES能减轻DDP诱导的呕吐和消化不良症状:GES+DDP阶段比格犬的症状评分较DDP阶段明显降低(24.50±1.45比31.83±2.75,P=0.028),并且呕吐次数也明显减少(3.7±0.8比5.5±1.2,P=0.028).但GES对DDP引起的胃电紊乱无明显影响.结论 DDP能诱导犬呕吐和胃电紊乱.串脉冲GES能明显减轻DDP引起的呕吐和消化不良症状,但对胃电紊乱无明显影响.     

Antro-fundic dysfunctions in functional dyspepsia

BACKGROUND & AIMS: Symptoms in functional dyspepsia have been related to impaired accommodation and hypersensitivity of the proximal stomach. We hypothesized that identification of putative antral dysfunctions provides a more comprehensive pathophysiological interpretation. METHODS: In 30 patients with functional dyspepsia and 22 healthy subjects, 2 consecutive studies were performed. In study I, with the subjects in the upright position, the proximal and distal stomach were selectively distended by bags containing air and water, respectively, while perception and fundic relaxation in response to antral distention were measured. In study II, by using air-filled bags connected to a tensostat, the proximal and the distal stomach were selectively distended by positioning the subjects on the right and left lateral decubitus, respectively, while perception, compliance, and the responses to intestinal nutrient infusion were measured. RESULTS: Patients with dyspepsia showed hypersensitivity of both the proximal stomach (discomfort at 30 +/- 3 g vs. 62 +/- 2 g in controls; P < 0.05) and the antrum (discomfort at 31 +/- 2 g vs. 53 +/- 4 g in controls; P < 0.05). Fundic and antral fasting tone was normal, but reflex fundic relaxation induced either by antral distention (3 +/- 16 mL at 80 mL of distention vs. 38 +/- 10 mL in controls; P < 0.05) or by intestinal nutrients (35 +/- 7 mL vs. 107 +/- 8 mL in controls; P < 0.05) was markedly impaired. CONCLUSIONS: Antral and fundic dysfunctions interact to produce the symptoms of functional dyspepsia, and impaired control of fundic accommodation may lead to overload of a hypersensitive antrum.     

Two-Channel Gastric Electrical Stimulation Accelerates Delayed Gastric Emptying Induced by Vasopressin

The aim of this study was to investigate the effects of two-channel gastric electrical stimulation (GES) on delayed gastric emptying, gastric dysrhythmias, and motion sickness-like symptoms induced by vasopressin. Seven dogs implanted with four pairs of gastric electrodes and a duodenal cannula were studied in four randomized sessions (saline, vasopressin, single-channel GES, and two-channel GES). The experiment in each session was conducted sequentially as follows: 30-min baseline, ingestion of a liquid meal, 30-min iv infusion of vasopressin or saline, and two 30-min postprandial recordings. In the GES sessions, GES was applied via the first pair of electrodes for single-channel GES or the first and third pairs of electrodes for two-channel GES. Gastric emptying was collected every 15 min via the cannula for a period of 90 min. Results were as follows. (1) Vasopressin induced gastric dysrhythmias, motion sickness-like symptoms, and delayed gastric emptying (P < 0.01, ANOVA). (2) GES normalized gastric dysrhythmias (P < 0.01) but showed no effects on vasopressin-induced emetic response. (3) Two-channel GES improved delayed gastric emptying induced by vasopressin. In comparison with the vasopressin session, two-channel GES, but not single-channel GES, significantly increased gastric emptying at 30 min (43.9 ± 12.6 vs. 27.5 ± 7.7%; P < 0.03), 60 min (75.3 ± 15.1 vs. 54.0 ± 17.8%; P < 0.05), and 90 min (91.6 ± 9.8 vs. 80.3 ± 9.0%; P < 0.05). GES with long pulses is able to normalize gastric dysrhythmias. Two-channel GES improves delayed gastric emptying induced by vasopressin.