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1 Division of Gastroenterology, Faculty of Medicine, University of Antwerp, Antwerp, Belgium
2 Department of Physiology, Faculty of Medicine and Health Sciences, UAE University, Al Ain, United Arab Emirates
* To whom correspondence should be addressed. E-mail: wlammers{at}smoothmap.org.
ackgrounds & Aims: Since the development of knockout animals, the mouse has become an important model to study gastrointestinal motility. However, little information is available on the electrical and contractile activities induced by distension in the murine small intestine. Methods: Spatiotemporal electrical mapping and mechanical recordings were made from isolated intestinal segments from different regions of the murine small intestine during distension. The electrical activity was recorded with 16 extracellular electrodes while motility was assessed simultaneously by tracking the border movements with a digital camera. Results: Distension induced propagating oscillatory contractions in isolated intestinal segments. These propagating contractions were dictated by the underlying propagating slow wave with superimposed spikes. The frequencies, velocities and direction of the propagating oscillations strongly correlated with the frequencies (r=0.86), velocities (r=0.84) and direction (r=1) of the electrical slow waves. L-NAME decreased the maximal diameter of the segment and reduced the peak contraction amplitude of the propagating oscillatory contractions while atropine and verapamil blocked the propagating oscillations. TTX had little effect on the maximal diameter and the peak contraction amplitude. Conclusion: Distension in the mice small intestine does not initiate peristaltic reflexes but induces a propagating oscillatory motor pattern which is determined by propagating slow waves with superimposed spikes. These spikes are cholinergic and calcium dependent.
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