Slow fluid infusion alters esophageal tone before onset of esophageal contraction in humans.

We investigated whether esophageal tone was altered by fluid infusion before the onset of esophageal contraction. In nine healthy volunteers, intraluminal esophageal pressure and esophageal pH were measured with a three-channel solid-state transducer and microglass electrodes, respectively. Saline or 0.1 N hydrochloric acid was infused at 0.25 ml/sec 5 cm above the lower esophageal sphincter. The effect of atropine (80 microg/kg, intravenously) was also studied. Infusion of either saline or hydrochloric acid suddenly increased the midesophageal intraluminal pressure (8.2-8.4 mm Hg) and decreased the pressure more distally (8.0-8.5 mm Hg) with a latency of 23 sec. There were no significant differences between the effects of saline and hydrochloric acid. Atropine significantly (P < 0.05) lessened the midesophageal increase in pressure, but only slightly inhibited the distal decrease. Atropine did not alter the latency. Esophageal tone was altered by slow fluid infusion. This previously unknown physiological response may be a mechanism for storing liquid in the esophageal body until the start of contractions for clearance.