Oesophageal intraluminal nitric oxide facilitates the acid-induced oesophago-salivary reflex.
BACKGROUND
The present study explores some aspects of the triggering of the acid-induced oesophago-salivary reflex. In addition to hydrogen ions, there are two acid-dependent molecules with messenger potential in the oesophageal lumen: CO2 and NO. The aim of this study was to clarify whether oesophageal NO and CO2 participate in the regulation of salivary neutralizing capacity in response to acid exposure.


METHODS
Healthy volunteers received oesophageal acidification composed of HCl, with NO3-, or HCO3- or NO3- and HCO3- in combination. In a second series of experiments, the exposure period was divided into 2 separate 10-min events. Saliva volume and titratable buffering capacity were used to calculate alkaline secretion.


RESULTS
Salivary alkaline secretion increased markedly following 20 min intraluminal exposure to HCl. The initial part of this response was 22% +/- 2.2% larger (P < 0.05) if NO3- was present. When HCO3- was added, or if NO3- and HCO3- were given simultaneously, the secretory response tended to be lower. The accumulated responses over 70 min to 2 short HCl exposures (10 min each separated by a 30 min 'rest') compared to one long one lasting 20 min were similar regardless of the presence of NO3-.


CONCLUSIONS
The data suggest that oesophageal intraluminal NO facilitates initiation of the oesophago-salivary reflex. CO2 seems to have a negligible effect on alkaline salivation, and repeated stimulation does not influence the magnitude of the response over time.
Casselbrant
A
A
Dept. of Gastro Research, Göteborg University, Göteborg, Sweden. anna.casselbrant@gastro.gu.se
Pettersson
A
A
Fändriks
L
L
D000328:Adult; D004947:Esophagus / Q000378:metabolism* / Q000503:physiopathology*; D005260:Female; D005764:Gastroesophageal Reflux / Q000209:etiology* / Q000378:metabolism / Q000503:physiopathology*; D006801:Humans; D006851:Hydrochloric Acid / Q000008:administration & dosage / Q000378:metabolism; D008297:Male; D009569:Nitric Oxide / Q000008:administration & dosage / Q000378:metabolism*; D012016:Reference Values; D012018:Reflex / Q000502:physiology; D012463:Saliva / Q000378:metabolism* / Q000502:physiology; D012472:Salivation / Q000187:drug effects / Q000502:physiology; D013997:Time Factors
D009569:Nitric Oxide; D006851:Hydrochloric Acid