Abstract no.: 5 Combined spatiotemporal and motility mapping of the murine small intestine during distension.

Background & aim Since the development of knock out animals, the mouse has emerged as the model species to study GI motility. However, little information is available on the electrical and contractile activities induced by distension in the murine small intestine. In the present study we investigated the electrical and associated motor activity during distension in isolated segments of the murine small intestine. Methods Short segments of the murine small intestine were mounted in a Tyrode-superfused organ bath. Upon distension to 3.0 cmH₂0 periods of oscillations were generated. The electrical and contractile activities of these oscillations were recorded with a longitudinal row of 16 extracellular electrodes and a digital video camera. The electrodes recorded the slow wave and spike activities. The video camera monitored changes in intestinal configuration. Both signals were analyzed with custom-developed software. In addition the effect of verapamil (3 × 10⁻⁵) and atropine (10⁻⁵) were examined. Results Distension induced the appearance of oscillatory contractions. Motility analyses revealed that these oscillations propagated. The majority propagated aborally (50%), while others propagated in the oral (33%) or in both directions (17%). The frequencies, velocities and directions of the propagating oscillations were strongly correlated with the frequencies (R = 0.81), velocities (R = 0.83) and directions (R = 1.0) of the electrical slow wave. Atropine ( n = 4) and verapamil ( n = 4) abolished the propagating oscillations. Conclusion The distension induced propagating oscillations are caused by propagating slow waves and its accompanying action potentials. Frequency, direction and velocity of these propagating oscillations are determined by the underlying slow wave activity. These propagating oscillation are cholinergic and calcium-dependent. [ABSTRACT FROM AUTHOR]