Reduction of the nociceptive response to gastric distension by nitrate ingestion in rats.
BACKGROUND
Dietary nitrates are known to produce nitric oxide in the stomach, which may influence gastric function.


OBJECTIVE
To investigate whether nitrate ingestion modifies gastric sensitivity to distension through a mechanism involving nitric oxide production.


METHODS
Nociception, associated with gastric distension ranging from 10 to 40 mmHg, was assessed in anaesthetized rats by the amplitude of cardiovascular depressor responses. Gastric volume corresponding to each distension was recorded. The following intragastric administrations (1 mL) were performed before distension: water (control), KNO3, NaNO3, KCl, NaCl (all at 0.1 mmol/kg), standard food (0.5 g), sodium nitroprusside, a nitric oxide donor (5 mg/kg), and haemoglobin, a nitric oxide scavenger (150 mg/kg) given either with water or KNO3.


RESULTS
In controls, the fall in blood pressure increased from 7.8 +/- 2.0 to 31.6 +/- 2. 7 mmHg at distending pressures from 10 to 40 mmHg, respectively. KNO3 significantly reduced the amplitude of blood pressure response for the highest distending pressures (35 and 40 mmHg), while KCl induced a reduction in blood pressure response at all gastric pressures. NaNO3 and NaCl did not induce significant changes in distension-induced depressor responses. Administration of 0.5 g of standard food or sodium nitroprusside reproduced the effect of KNO3, which was reversed by haemoglobin. None of the compounds modified the gastric pressure-volume relationship, except KNO3, which increased gastric volume for the lowest distending pressures, and haemoglobin, which reduced the volume for the highest pressure.


CONCLUSIONS
Ingestion of potassium nitrate reduces the sensitivity to gastric distension, through a mechanism involving nitric oxide.
Rouzade
M L
ML
Neuro-Gastroenterology & Nutrition Unit, Institut National de la Recherche Agronomique, Toulouse, France.
Anton
P
P
Fioramonti
J
J
Garcia-Villar
R
R
Theodorou
V
V
Bueno
L
L
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D004032:Diet; D008297:Male; D009566:Nitrates / Q000008:administration & dosage / Q000494:pharmacology*; D010147:Pain Measurement; D017680:Potassium Compounds / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D013270:Stomach / Q000187:drug effects* / Q000502:physiology*
D009566:Nitrates; D017680:Potassium Compounds; C023844:potassium nitrate