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

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. 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. The myoelectric signals of the stomach, ileum and caecum were at 3–5, 20–25 and 1–3 cpm, 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. 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.