Mechanoreceptors of the proximal stomach: Role in triggering transient lower esophageal sphincter relaxation.
OBJECTIVE
The role of fundic tension and stretch mechanoreceptors in triggering transient lower esophageal sphincter (LES) relaxation is still unknown. This information would be useful for the development of effective pharmacologic strategies. To elucidate this topic, gastric contractile activity was modified during isovolumetric gastric distention at 2 different volumes.


METHODS
LES (Dentsleeve) and gastric (barostat) motility were recorded in 21 healthy subjects during studies comprising two 30-minute isovolumetric gastric distentions (placebo and glucagon or erythromycin). Glucagon (bolus of 4.8 microg/kg plus infusion of 9.6 microg x kg(-1) x h(-1)) was administered at high intragastric volume (i.e., 75% of the threshold volume for discomfort; n = 7) and erythromycin (3 mg/kg) at high (n = 7) and low intragastric volume (i.e., at perception threshold; n = 7).


RESULTS
Glucagon decreased (P < 0.05) baseline intragastric pressure and abolished gastric contractions (0 vs. 16.7 +/- 2.3), whereas erythromycin increased (P < 0.05) baseline pressure and doubled (P < 0.05) the rate of gastric contractions at both volumes. Neither drug affected the rate of transient LES relaxations. Low intragastric volume induced a lower rate of transient LES relaxations (1.7 +/- 0.3 vs. 5.7 +/- 1.1; P < 0.01) and gastric contractions (11.8 +/- 2.5 vs. 20.5 +/- 3.1; P < 0.05) compared with high volume but similar baseline intragastric pressure (10.6 +/- 0.6 vs. 11.9 +/- 0.9 mm Hg).


CONCLUSIONS
Stretch receptors (gastric volume) seem to be more relevant than tension receptors in triggering transient LES relaxation.
Penagini
Roberto
R
Cattedra di Gastroenterologia, Dipartimento di Scienze Mediche, University of Milan, Italy.
Carmagnola
Stefania
S
Cantù
Paolo
P
Allocca
Mariangela
M
Bianchi
Paolo A
PA
D000328:Adult; D001786:Blood Glucose / Q000032:analysis; D004917:Erythromycin / Q000494:pharmacology; D004943:Esophagogastric Junction / Q000502:physiology*; D005260:Female; D005765:Gastrointestinal Agents / Q000494:pharmacology; D005769:Gastrointestinal Motility / Q000187:drug effects; D005934:Glucagon / Q000494:pharmacology; D006801:Humans; D008297:Male; D008465:Mechanoreceptors / Q000502:physiology*; D009126:Muscle Relaxation / Q000502:physiology*; D011312:Pressure; D013270:Stomach / Q000294:innervation* / Q000502:physiology*
D001786:Blood Glucose; D005765:Gastrointestinal Agents; D004917:Erythromycin; D005934:Glucagon