A quantitative approach to recording peristaltic activity from segments of rat small intestine in vivo

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Abstract
We have developed methods that allow correlation of propulsive reflexes of the intestine with measurements of intraluminal pressure, fluid movement and spatio‐temporal maps of intestinal wall movements for the first time in vivo. A segment of jejunum was cannulated and set up in a Trendelenburg recording system while remaining connected to the vascular and nerve supply of the anaesthetized rat. The resting intraluminal pressure in intact intestine was 2–4 mmHg. Hydrostatic pressures of 2, 4, 8 and 16 mmHg were imposed. At a baseline pressure of 4 mmHg, propulsive waves generated pressures of 9 ± 1 mmHg, that progressed oral to anal at 2–5 mm s−1. Individual propulsive waves propelled 0.8 ± 0.4 mL of fluid. The frequency of propulsive waves increased with pressure, but peristaltic efficiency (mL per contraction) decreased with pressure increase between 4 and 16 mmHg. Atropine, as a bolus, transiently blocked peristalsis, but caused maintained block when infused. Hexamethonium blocked propulsive contractions. Inhibition of nitrergic transmission converted regular peristalsis to non‐propulsive contractions. These studies demonstrate the utility of an adapted Trendelenburg method for quantitative investigation of motility and pharmacology of enteric reflexes in vivo.