High concentrations of ammonia, but not volatile amines, in gastric juice of subjects with Helicobacter pylori infection.
BACKGROUND
Helicobacter pylori (H. pylori) produces large amounts of ammonia. Based on higher readings obtained with an ammonia-sensitive electrode when compared to a specific enzymatic assay, it has been claimed that H. pylori also produces potentially toxic volatile amines.


METHODS
We measured ammonia concentrations (NH3) in gastric aspirates from 11 H. pylori positive subjects (22-40 y, 6 M), using an ammonia electrode sensitive to ammonia and amines, and an enzymatic assay specific for ammonia. Continuous aspiration was performed overnight and 220 aspirates were analyzed before and 6 weeks after cure of H. pylori. Gastric samples were diluted 1:3 (before cure) and 1:1 (after cure) according to dilution curves constructed prior to the assays.


RESULTS
Median (95% CI) NH3 detected by the electrode/enzymatic assay were 4.34 mM[4.12-4.61]/4.50 mM [4.28-4.68] (p > .05) before cure and 0.54 mM[0.42-0.60]/0.73 mM[0.71-0.81] after cure (p > .05). Intra-class correlation coefficient between the two methods was 0.91 before cure and 0.90 after cure (p < .001). Without dilution, the enzymatic assay was linear for NH3 from 0.01 to 1 mM and saturated at 2.5 mM; the electrode was linear for NH3 from 0.01 to 20 mM. When appropriate dilutions were performed, the enzymatic assay was accurate for NH3 greater than 2.5 mM.


CONCLUSIONS
In subjects with H. pylori infection there is a high NH3 in gastric juice; production of volatile amines appears to be negligible in vivo. An ammonia-sensitive electrode and a specific enzymatic assay are both suitable methods for determining NH3 in the gastric juice of subjects with H. pylori infection.
Verdú
E F
EF
Division of Gastroenterology, CHUV, Lausanne, Switzerland.
Armstrong
D
D
Sabovcikova
L
L
Idström
J P
JP
Cederberg
C
C
Blum
A L
AL
Bercík
P
P
D000328:Adult; D000588:Amines / Q000032:analysis*; D000641:Ammonia / Q000032:analysis* / Q000378:metabolism; D015374:Biosensing Techniques; D005260:Female; D005750:Gastric Juice / Q000737:chemistry*; D016481:Helicobacter Infections / Q000382:microbiology*; D016480:Helicobacter pylori / Q000201:enzymology / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged
D000588:Amines; D000641:Ammonia