Objectives/Hypothesis: Sensory impulses from the pharynx induce contraction
of the upper esophageal sphincter (UES), relaxation of the lower esophagea
l sphincter (LES), and inhibition of peristalsis. To determine 1) the magni
tude of UES contractile response to threshold volume of fluid that induces
LES relaxation and 2) the effect of rapid pharyngeal air stimulation on LES
resting pressure and its concurrent influence on the UES and progression o
f esophageal peristalsis. Methods: Eleven healthy volunteers (age, 31 +/- 2
y) were studied by concurrent UES, esophageal-body, and LES manometry. Res
ults: At a threshold volume of 0.3 +/- 0.05 mt, injections of water into th
e pharynx directed posteriorly, resulted in complete LES relaxation, Durati
on of these relaxations averaged 19 +/- 1 seconds. In 10 of 11 subjects, th
ese relaxations were accompanied by a simultaneous increase in UES resting
tone that averaged 142% +/- 27% above preinjection values. Pharyngeal stimu
lation by rapid air injection resulted in complete LES relaxation in 8 of t
he II subjects (threshold volume, 14 +/- 6 mt). Five of 8 developed a concu
rrent mild increase in resting UES pressure (17% +/- 6% above preinjection
values) (P <.05), Pharyngeal water injection inhibited the progression of t
he peristaltic pressure wave at all tested sites and in all subjects, but p
haryngeal air injection in only 2 of the 11 studied subjects. Conclusions:
The inhibitory effect of pharyngeal water injection on LES resting pressure
is accompanied by a substantial contractile effect on the UES, Although st
imulation of the pharynx by rapid air injection may induce LES re laxation,
its inhibitory effect on esophageal peristalsis and stimulatory effect on
UES pressure are negligible compared with that of water injection.