Quantification of anterograde, retrograde and segmental contractions

We utilized “GutCode”⁴⁹ for the analysis of diameter data obtained from four EW trackers positioned along the oral-to-aboral axis of intestinal segments. Contractions were categorized into anterograde, retrograde, and segmental based on relative movements of adjacent trackers. Anterograde was noted when the proximal tracker detected contraction followed by relaxation detected by the distal tracker. Retrograde was identified when the proximal tracker noted relaxation followed by contraction detected by the distal tracker.

Segmental contractions were recognized when both proximal and distal trackers detected contractions simultaneously. To quantify contraction strength, we divided the sum of the amplitudes by time, assigning positive values to anterograde, negative values to retrograde, and segmental values based on their overall inclination toward anterograde or retrograde with a positive or a negative sign.

Since “GutCode”⁴⁹ processed data obtained at a 50 msec intervals, and contraction-relaxation cycle occur at 0.7 Hz, where each wave takes ~1.4 s to complete, only minor shifts were analyzed in anterograde, retrograde, or segmental contractions between EW trackers for each data point. In addition, the slow waves generating propulsive movements can instantaneously change direction and speed of propagation⁵⁰. Therefore, to determine the overall contraction direction, we introduced “net amplitude”, accounting for small amplitude shifts among all four trackers. A “net amplitude” > 0 indicated anterograde, while <0 indicated retrograde contractions. “Net amplitude” allowed for comparisons between different discharge groups and contraction phases. These recordings provided insights into various contractions, tabulating their frequency, strength, duration, amplitude, retrograde, segmental, and anterograde characteristics, and their impact on intestinal DD. This tabulation facilitated easy comparisons between studied tissue segments (Figs. 1a–d, 5a–i, 6a–e and Tables 1 and ​and22).