Cholinergic stimulation induces asynchrony between the circular and longitudinal muscle contraction during esophageal peristalsis

In healthy subjects, a close temporal correlation exists between contractions of the circular muscle (CM) and longitudinal muscle (LM) layers of the esophagus. Patients with nutcracker esophagus show disassociation between the peak of contractions of the CM and LM layers and the peak of contraction 1-3 s apart (Jung HY, Puckett JL, Bhalla V, Rojas-Feria M, Bhargava V, Liu J, Mittal RK. Gastroenterology 128: 1179-1186, 2005). The purpose of the present study was to evaluate the effect of acetylcholinesterase inhibitor (edrophonium) and acetylcholine receptor antagonist (atropine) on human esophageal peristalsis in normal subjects. High-frequency intraluminal ultrasound imaging and manometry were performed simultaneously during swallow-induced peristalsis in ten normal subjects. Standardized 5-ml water swallows were recorded 2 cm above the lower esophageal sphincter under three study conditions: control, edrophonium (80 microg/kg iv), and atropine (10 microg/kg iv). A close temporal correlation exists between the peak pressure and peak wall thickness during the control period. The mean time lag between the peak LM and peak CM contraction was 0.03 s. After edrophonium administration, the mean contraction amplitude increased from 101 +/- 9 mmHg to 150 +/- 20 mmHg (P < 0.05) and mean peak muscle thickness increased from 3.0 +/- 0.2 mm to 3.6 +/- 0.3 mm (P < 0.01), and duration of both CM and LM contractions were also increased. Furthermore, the mean time difference between the peak LM and CM was increased to 1.1 s, (ranging 0.2 to 3.4 s) (P < 0.0001). We conclude that cholinomimetic agent induces discoordination between the two muscle layers of the esophagus.