Dynamic slow‐wave interactions in the rabbit small intestine defined using high‐resolution mapping

Abstract

Background The motility in the small intestine is governed in part by myogenic bio‐electrical events, known as slow waves. High‐resolution multi‐electrode mapping has improved our understanding of slow‐wave propagation in the small intestine but has been applied in a limited number of in vivo animal studies. This study applied high‐resolution mapping to investigate slow waves in the rabbit small intestine. Methods A high‐resolution flexible printed circuit board array (256 electrodes; 4 mm spacing) was applied in vivo to the rabbit intestine. Extracellular slow‐wave activity was acquired sequentially along the length of the intestine. Key results and conclusions The majority of the slow waves propagated in the antegrade direction (56%) while retrograde patterns were primarily observed in the distal intestine (29%). Colliding slow‐wave events were observed across the length of the small intestine (15%). The interaction of competing pacemakers was mapped in spatiotemporal detail. The frequency and velocity of the slow waves were highest in the duodenum compared to ileum (20.0 ± 1.2 cpm vs 10.5 ± 0.9 cpm, P < 0.001; 14.4 ± 3.4 mm/s vs 12.3 ± 3.4 mm/s; P < 0.05). Inferences In summary, extracellular serosal slow‐wave activity was quantified spatiotemporally along the length of the rabbit intestine. In particular, the study provides evidence toward the presence and interaction of slow‐wave pacemakers acting along the small intestine and how they may contribute to the slow‐wave frequency gradient along the length of the intestine.

Systematic review of small intestine pacing parameters for modulation of gut function

“…This response may not be unique to the jejunum, but rather influenced by pacing parameters such as pulse amplitude, and pulse width. Pacing investigations in the ileum has only been reported in one study, with the ileum also likely being more challenging to successfully pace because of the lower amplitude slow‐wave activity in that region of the intestine 30,36 . It is important to note that frequency and amplitude gradients are distinct across the small intestinal segments, 30,33,36 and therefore, optimizing parameters for each region is likely to be necessary.…”

Relationship Between Intestinal Slow-waves, Spike-bursts, and Motility, as Defined Through High-resolution Electrical and Video Mapping

“…Experiments were performed in vivo on female cross-breed, weaner pigs, and female New Zealand white rabbits, both established models of small intestine slow-wave and spike-burst investigation using HR mapping methods. 27 , 31 The use of both animal species in this study allowed for a broad investigation to account for potential inter-species variability. Animal care, preparation and anesthesia were performed as previously described.…”

“…Animal care, preparation and anesthesia were performed as previously described. 27 , 31 The experimental arrangement is shown in Figure 1 . In summary, a midline laparotomy was performed, and a section of the jejunum was exteriorized and placed on top of an electrode array that consisted of 128 channels arranged in a 16 × 8 grid with 4 mm inter-electrode spacing.…”

Mucosa-interfacing electronics

“…Similarly, pulmonary mucosal impedance directly reflects pulmonary function and can be used to monitor diseases such as pneumonia and asthma 15 . The slow-wave potential, a rhythmic electrophysiological event in the gastrointestinal (GI) tract, is highly correlated to gastric functions 16 , 17 . Last, the external urethral sphincter muscle regulates the timely passage of urine through the urethra, and external urethral sphincter electromyographic activity is used to study lower urinary tract function 18 .…”