Figure 9.

Defining a stimulus for propagating contractions. The top panels (A–D) represent the data from propagating contractions. The bottom panels (E–H) are collated from non-propagating contractions. The panels (B,F) represent the mean dilations (increase from baseline diameter) in a 4 cm region above and 8 cm region below the site of initiation of the active propagating (white box in B) and active non-propagating (white box in F) contractions. All active propagating and non-propagating contractions that originated within the proximal 4 cm or distal 8 cm of the preparation were excluded from this analysis. These panels also capture a 2 s time epoch leading up to and following the active contractions. (A,E) Indicated the mean dilation in the 2 s period prior to the initiation of the active contractions. The black line in (A,E) indicates the mean dilation at each point in time along the 12 cm region of colon and the thickness of the line indicates the 95% confidence interval. The thin gray lines indicated the standard deviation. The mean dilation immediately prior to the active propagating contractions is 2.7 mm which is significantly greater (P < 0.0001) than mean dilation prior to the active non-propagating contractions (1.6 mm). The right hand side of figure shows the relation that exists between the active states (contraction red and relaxation blue) and the active propagating (C,D) and non-propagating (G,H) contractions. Note that there is a significantly (P < 0.005) degree of active relaxation associated with active propagating contractions in comparison to active non-propagating contractions (C,G).