The Participation of the Nitrergic Pathway in Increased Rate of Transitory Relaxation of Lower Esophageal Sphincter Induced by Rectal Distension in Dogs

Abstract

ContextThe rectal distension in dogs increases the rate of transitory lower esophageal sphincter relaxation considered the main factor causing gastroesophageal reflux.ObjectivesThe aim of this study was evaluate the participation of the nitrergic pathway in the increased transitory lower esophageal sphincter relaxation rate induced by rectal distension in anesthetized dogs.MethodsMale mongrel dogs (n = 21), weighing 10-15 kg, were fasted for 12 hours, with water ad libitum. Thereafter, they were anesthetized (ketamine 10 mg.Kg-1+ xylazine 20 mg.Kg-1), so as to carry out the esophageal motility evaluation protocol during 120 min. After a 30-minute basal period, the animals were randomly intravenous treated whith: saline solution 0.15M (1ml.Kg-1), L-NAME (3 mg.Kg-1), L-NAME (3 mg.Kg-1) + L-Arginine (200 mg.Kg-1), glibenclamide (1 mg.Kg-1) or methylene blue (3 mg.Kg-1). Forty-five min after these pre-treatments, the rectum was distended (rectal distension, 5 mL.Kg-1) or not (control) with a latex balloon, with changes in the esophageal motility recorded over 45 min. Data were analyzed using ANOVA followed by Student Newman-Keuls test.ResultsIn comparison to the respective control group, rectal distension induces an increase in transitory lower esophageal sphincter relaxation. Pre-treatment with L-NAME or methylene blue prevents (P<0.05) this phenomenon, which is reversible by L-Arginine plus L-NAME. However, pretreating with glibenclamide failed to abolish this process.ConclusionsTherefore, these experiments suggested, that rectal distension increases transitory lower esophageal sphincter relaxation in dogs via through nitrergic pathways.

Rectal distention increases the frequency and duration of transient lower esophageal sphincter relaxations in anesthetized dogs– a putative rectoesophageal reflex

“…17 This methodological set up has been utilized before in other published studies. While Palheta 8 and Lehmann 13 utilized this method in developing their protocols involving GD in dogs, Youle had earlier proved that a painless RD in dogs elicited a finding previously published by our laboratory. 8 In a similar fashion, tLSER remained unaltered in animals subjected to prior-bilateral pudendi and spinal cord resection (Table 3), suggesting a probable participation of the rectal sensory neuron and the parasympathetic tone afferent in modulating LEStone due to rectal distention.…”

“…Our laboratory has utilized the conventional manometry in carrying out other tests in other anterior publications. 8 As principle, manometry enables continuous measurement of the frequency of tLESR episodes with their simultaneous pressures, leading to a better comprehension of GERD, by identifying tLESR as the main permissive mechanism for GERD. 16 Using a low-compliance manometric perfusion technique, we obtained results on gastric and LES pressures which were similar to those published by others.…”

“…6 In addition, a revision of literature shows that the prevalence of GERD symptoms in patients with inflammatory bowel disease is approximately 54%, 7 an index which increases in patients with dominating constipation symptoms vis-a-vis diarrheic subjects. 8 Probably this phenomenon is attributed to fermentation of undigested starch by colonic microbioma which generates short-chain fatty acids and hydrogen 9 that elicit viscerovisceral feedback in healthy subjects, 3 provoking a distention of the proximal stomach thus triggering tLESR. 10 In pre-clinical studies with dogs, it was observed by esophageal manometry and pH monitoring that they possess a capacity for spontaneous GER during tLESRs, of similar characteristics to that of the human being.…”