Prediction of gastroesophageal reflux episodes by smooth muscle electromyography: A translational study in rats and adolescents.

Aims: Our aim was to measure the myoelectric modifications during gastric acid secretion along with the gastric pH in a rat model and to detect the gastrointestinal (GI) myoelectric changes in adolescents suffering from gastroesophageal reflux disease (GERD) along with the esophageal pH measurement. Main methods: In anesthetized rats, gastric acid secretion was initiated with intragastric histamine (50 mg/kg), and gastric pH, GI myoelectric activity and mechanical GI contractions were measured with intragastric pH electrode, subcutaneously implanted smooth muscle electromyography (SMEMG) electrodes and organ implanted strain gauges, respectively. In the clinical study, esophageal pH and GI myoelectric activity were measured in adolescents suffering from GERD with intraesophageal pH electrode and SMEMG electrodes placed on the abdominal surface, respectively. The SMEMG records were analyzed by fast Fourier transformation (FFT) and power spectrum density maximum (PsDmax) values were calculated for the GI segments. Key findings: In rats, histamine initiated an immediate increase in gastric PsDmax, which preceded the significant reduction in gastric pH by 75 min. The myoelectric change was independent of mechanical GI contractions. In adolescents, the GERD episodes were preceded by a significant increase in gastric PsDmax 45 min earlier. These changes were independent of motion or meals. Significance: Increased gastric myoelectric activity during histamine stimulation or GERD might be linked to the enhanced activity of the gastric proton pump, indicating a link between gastric acid secretion and GERD episodes. It is supposed that SMEMG might be a tool for predicting forthcoming reflux episodes in GERD.

Non-invasive smooth muscle electromyography (SMEMG) as a novel monitoring technology of the gastrointestinal tract of awake, free-moving pigs-A pilot study.

There are several mathematical models and measurements to determine the efficiency of the digestibility of different feedstuffs. However, there is lack of information regarding the direct methods or measurement techniques used to analyse the physical response of the different parts of the gastrointestinal tract (GIT) of growing pigs to different diets. Smooth muscle electromyography (SMEMG) is a non-invasive method for the measurement of gastrointestinal myoelectrical activity. In the present study, SMEMG methodology has been adapted from laboratory rats to pigs, and the effects of feedstuffs with control (CTR) or experimentally increased (EXP) amounts of fibre were investigated on gastrointestinal tract motility. Nine barrow pigs ((Danish Landrace × Danish Yorkshire) × Danish Duroc) were used (30 ± 3 kg), and their CTR and EXP feedstuffs contained 29 and 49 g/kg crude fibre (CF), respectively. Myoelectric activities of the stomach, ileum and caecum were detected in the awake pigs by a pair of electrodes. The recorded myoelectric signals were analysed with fast Fourier transformation (FFT), and the spectra were expressed in GIT section-specific cycles per minutes (cpm) values and the maximum power spectrum density (PsDmax). A significant increase (P < 0.001) was observed in the value of the PsDmax of the small intestine (20-25 cpm) as a consequence of the EXP diet. The PsDmax values of the stomach (3-5 cpm) and large intestine (1-3 cpm) did not show any significant change in pigs fed the EXP diet. As a direct and non-invasive method, SMEMG is suitable for the rapid evaluation of the effects of diets with different fibre contents on the GIT of non-anaesthetised, free-moving pigs.

Detection of acute stress by smooth muscle electromyography: A translational study on rat and human.

AIMS: Non-invasive and simultaneous recording of gastrointestinal (GI) activity during stress induction is still an unexplored field. In our previous investigation, the stress-induced alteration of the gastrointestinal tract was explored in rats. Our aims were to expand our previous rat experiment and to induce stress response in rats (Study 1) and humans (Study 2) to detect the GI tract activity, heart rate and body temperature. MATERIALS AND METHODS: In the preclinical sample, acute stress was induced by immobilization in Sprague-Dawley rats (N = 10). Acute stress response was generated by the Trier Social Stress Test among healthy volunteers (N = 16). Detection of acute stress was measured by using smooth muscle electromyography, which recorded the myoelectric waves of the gastrointestinal tract (stomach, ileum and colon) simultaneously with heart rate and body temperature in rats and humans. KEY FINDINGS: The myoelectric waves of the stomach, the cecum and the ileum increased during immobilization in rats, rising in parallel with heart rate and the dermal temperature of the abdominal surface. The same alterations were found during the stress period among humans, except in the case of the colon, where no change was detected. SIGNIFICANCE: The crucial role of the GI tract in stress response was revealed by translating the outcome of basic research into human results. The similar GI alterations during stress in rats and humans underpin the robustness of our findings. In summary, our preliminary translational-based study can serve as an appropriate basis for further human studies.

Identification of myoelectric signals of pregnant rat uterus: new method to detect myometrial contraction.

AIM: To develop an electromyography method for pregnant rat uterus in vivo and to separate myometrial signals from the gastrointestinal tract signals. METHODS: Pregnant Sprague-Dawley rats (n=8) were anaesthetized and their stomach, small intestine, and large intestine were removed from the abdomen. A pair of thread electrodes was inserted into the uterus, while a pair of disk electrodes was placed subcutaneously above the myometrium. Additionally, a strain gauge sensor was fixed on the surface of the myometrium and cecum for the parallel detection of mechanical contractions in rats (n=18) with intact gastrointestinal tract. The filtered electric signals were amplified and recorded by an online computer system and analyzed by fast Fourier transformation. The frequency of the electric activity was characterized by cycle per minute (cpm), the magnitude of the activity was described as power spectrum density maximum (PsDmax). RESULTS: The frequency of the pregnant uterine activity was 1-3 cpm, which falls within the same range as that of cecum. Measuring by both electrodes, oxytocin (1 µg/kg) increased and terbutaline (50 µg/kg) decreased the PsDmax by 25%-50% (P<0.001) and 25%-40% (P<0.01), respectively. We found a strong positive correlation between the alterations of PsDmax values and the strain gauge sensor-detected mechanical contractions (area under curve). The GI specific compounds (neostigmine, atropine) mainly affected the cecal activity, while myometrium specific drugs (oxytocin, terbutaline) influenced the myometrial signals only. Conclusion Our method proved to be able to detect the myoelectric activity that reflects the mechanical contraction. The overlapping myometrial and cecal signals are not separable, but they can be distinguished based on the much higher activity and different pharmacological reactivity of the pregnant uterus. Thus, the early signs of contractions can be detected and labor may be predicted in a fast and sensitive way.

Correlation between slow-wave myoelectric signals and mechanical contractions in the gastrointestinal tract: Advanced electromyographic method in rats.

AIM: Gastrointestinal motility disorders are presumed to be associated with abnormalities of the generation of slow-wave electric impulses. A requirement for the development of non-invasive clinical methods for the diagnosis of motility disorders is the identification of these signals. We set out to separate and characterize the signals from the various sections of the gastrointestinal tract and to detect changes in the smooth muscle electromyography (SEMG) signals. METHODS: Partially resected (stomach-small intestine, stomach-large intestine or small and large intestine) or non-resected male SPRD rats were measured under deep anaesthesia. Bipolar thread and disk electrodes and strain gauge sensors were used for SEMG and the detection of mechanical contractions, respectively. The electric activity was characterized by cycle per minute (cpm) and power spectrum density maximum (PsDmax) W by fast Fourier transformation analysis. Contractions were evaluated by area under the curve analysis. RESULTS: The myoelectric signals of the stomach, ileum and caecum were at 3-5, 20-25 and 1-3cpm, respectively. Neostigmine increased (40-60%), while atropine decreased (30-50%) the PsDmax values. However, the cpm values remained unchanged. Linear regression revealed a good correlation between the PsDmax values and the smooth muscle contractions. CONCLUSIONS: Electric signals of the same character were recorded from the organ and from the abdominal surface. The change in PsDmax perfectly reflects the change in the contractions of the smooth muscle. These results may serve as the basis for non-invasive gastrointestinal measurements in experimental animals, which can be translated into clinical practice for motility studies.